diff --git a/.gitignore b/.gitignore
index 9289795d18..9158da40b5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,5 @@ tests/PersistentCollections/*
 phpunit.xml
 composer.lock
 vendor/
+.phpcs-cache
+phpcs.xml
diff --git a/.travis.yml b/.travis.yml
index a0da4148a7..d51e9ccb3b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -43,11 +43,17 @@ jobs:
         - composer update --prefer-lowest
 
     - stage: Code Quality
-      php: 7.2
-      env: SERVER_VERSION="3.6" KEY_ID="2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5"
+      php: 7.1
+      env: STATIC_ANALYSIS SERVER_VERSION="3.6" KEY_ID="2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5"
       script:
         - vendor/bin/phpstan analyse -l 1 lib
 
+    - stage: Code Quality
+      php: 7.1
+      env: CODING_STANDARDS SERVER_VERSION="3.6" KEY_ID="2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5"
+      script:
+        - vendor/bin/phpcs
+
 before_install:
   - mv ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini{,.disabled} || echo "xdebug not available"
   - sudo apt-key adv --keyserver ${KEY_SERVER} --recv ${KEY_ID}
diff --git a/composer.json b/composer.json
index 22dd2ac8ea..79d32b00be 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,8 @@
     "require-dev": {
         "phpunit/phpunit": "^7.0",
         "jmikola/geojson": "^1.0",
-        "phpstan/phpstan": "^0.9.2"
+        "phpstan/phpstan": "^0.9.2",
+        "doctrine/coding-standard": "^4.0"
     },
     "autoload": {
         "psr-0": { "Doctrine\\ODM\\MongoDB": "lib/" }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Builder.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Builder.php
index e1fcd0cd0f..ee2657ae0f 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Builder.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Builder.php
@@ -1,15 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Iterator\CachingIterator;
 use Doctrine\ODM\MongoDB\Iterator\HydratingIterator;
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Query\Expr as QueryExpr;
 use GeoJson\Geometry\Point;
 use MongoDB\Collection;
 use MongoDB\Driver\Cursor;
+use function array_map;
+use function array_merge;
+use function array_unshift;
+use function is_array;
 
 /**
  * Fluent interface for building aggregation pipelines.
@@ -26,7 +34,7 @@ class Builder
     /**
      * The ClassMetadata instance.
      *
-     * @var \Doctrine\ODM\MongoDB\Mapping\ClassMetadata
+     * @var ClassMetadata
      */
     private $class;
 
@@ -50,7 +58,6 @@ class Builder
     /**
      * Create a new aggregation builder.
      *
-     * @param DocumentManager $dm
      * @param string $documentName
      */
     public function __construct(DocumentManager $dm, $documentName)
@@ -127,8 +134,6 @@ public function bucketAuto()
      * the pipeline returns an error.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/collStats/
-     * @since 1.5
-     *
      * @return Stage\CollStats
      */
     public function collStats()
@@ -200,7 +205,7 @@ public function facet()
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/geoNear/
      *
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return Stage\GeoNear
      */
     public function geoNear($x, $y = null)
@@ -221,7 +226,9 @@ public function geoNear($x, $y = null)
     public function getPipeline()
     {
         $pipeline = array_map(
-            function (Stage $stage) { return $stage->getExpression(); },
+            function (Stage $stage) {
+                return $stage->getExpression();
+            },
             $this->stages
         );
 
@@ -240,12 +247,12 @@ function (Stage $stage) { return $stage->getExpression(); },
     /**
      * Returns a certain stage from the pipeline
      *
-     * @param integer $index
+     * @param int $index
      * @return Stage
      */
     public function getStage($index)
     {
-        if ( ! isset($this->stages[$index])) {
+        if (! isset($this->stages[$index])) {
             throw new \OutOfRangeException("Could not find stage with index {$index}.");
         }
 
@@ -311,7 +318,7 @@ public function indexStats()
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/limit/
      *
-     * @param integer $limit
+     * @param int $limit
      * @return Stage\Limit
      */
     public function limit($limit)
@@ -424,7 +431,7 @@ public function replaceRoot($expression = null)
      *
      * @see https://docs.mongodb.org/manual/reference/operator/aggregation/sample/
      *
-     * @param integer $size
+     * @param int $size
      * @return Stage\Sample
      */
     public function sample($size)
@@ -438,7 +445,7 @@ public function sample($size)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/skip/
      *
-     * @param integer $skip
+     * @param int $skip
      * @return Stage\Skip
      */
     public function skip($skip)
@@ -456,7 +463,7 @@ public function skip($skip)
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/sort/
      *
      * @param array|string $fieldName Field name or array of field/order pairs
-     * @param integer|string $order   Field order (if one field is specified)
+     * @param int|string   $order     Field order (if one field is specified)
      * @return Stage\Sort
      */
     public function sort($fieldName, $order = null)
@@ -497,7 +504,6 @@ public function unwind($fieldName)
     }
 
     /**
-     * @param Stage $stage
      * @return Stage
      */
     protected function addStage(Stage $stage)
@@ -524,18 +530,13 @@ private function applyFilters(array $query)
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister()
     {
         return $this->dm->getUnitOfWork()->getDocumentPersister($this->class->name);
     }
 
-    /**
-     * @param Cursor $cursor
-     *
-     * @return Iterator
-     */
     private function prepareIterator(Cursor $cursor): Iterator
     {
         $class = null;
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Expr.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Expr.php
index 6261455a48..cbd1004158 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Expr.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Expr.php
@@ -1,10 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation;
 
 use Doctrine\Common\Persistence\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\DocumentManager;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Types\Type;
+use function array_map;
+use function array_merge;
+use function func_get_args;
+use function is_array;
+use function is_string;
+use function substr;
 
 /**
  * Fluent interface for building aggregation pipelines.
@@ -57,7 +66,6 @@ public function __construct(DocumentManager $dm, ClassMetadata $class)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function abs($number)
     {
@@ -180,7 +188,6 @@ public function anyElementTrue($expression)
      * @param mixed|self $index
      * @return $this
      *
-     * @since 1.3
      */
     public function arrayElemAt($array, $index)
     {
@@ -231,7 +238,6 @@ public function case($expression)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function ceil($number)
     {
@@ -284,7 +290,6 @@ public function concat($expression1, $expression2, ...$expressions)
      * @param mixed|self ...$arrays Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function concatArrays($array1, $array2, ...$arrays)
     {
@@ -338,7 +343,7 @@ public static function convertExpression($expression)
      * The date argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/dateToString/
-     * @param string $format
+     * @param string     $format
      * @param mixed|self $expression
      * @return $this
      */
@@ -455,7 +460,6 @@ public function eq($expression1, $expression2)
      * @param mixed|self $exponent
      * @return $this
      *
-     * @since 1.3
      */
     public function exp($exponent)
     {
@@ -467,7 +471,6 @@ public function exp($exponent)
      *
      * @return static
      *
-     * @since 1.3
      */
     public function expr()
     {
@@ -515,7 +518,6 @@ public function field($fieldName)
      * @param mixed|self $cond
      * @return $this
      *
-     * @since 1.3
      */
     public function filter($input, $as, $cond)
     {
@@ -546,7 +548,6 @@ public function first($expression)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function floor($number)
     {
@@ -632,7 +633,6 @@ public function ifNull($expression, $replacementExpression)
      * support matching by regular expressions.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/in/
-     * @since 1.5
      * @param mixed|self $expression
      * @param mixed|self $arrayExpression
      * @return $this
@@ -648,11 +648,10 @@ public function in($expression, $arrayExpression)
      * found, returns -1.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfArray/
-     * @since 1.5
-     * @param mixed|self $arrayExpression Can be any valid expression as long as it resolves to an array.
+     * @param mixed|self $arrayExpression  Can be any valid expression as long as it resolves to an array.
      * @param mixed|self $searchExpression Can be any valid expression.
-     * @param mixed|self $start Optional. An integer, or a number that can be represented as integers (such as 2.0), that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param mixed|self $end An integer, or a number that can be represented as integers (such as 2.0), that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param mixed|self $start            Optional. An integer, or a number that can be represented as integers (such as 2.0), that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param mixed|self $end              An integer, or a number that can be represented as integers (such as 2.0), that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      * @return $this
      */
     public function indexOfArray($arrayExpression, $searchExpression, $start = null, $end = null)
@@ -675,11 +674,10 @@ public function indexOfArray($arrayExpression, $searchExpression, $start = null,
      * found, returns -1.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfBytes/
-     * @since 1.5
-     * @param mixed|self $stringExpression Can be any valid expression as long as it resolves to a string.
+     * @param mixed|self $stringExpression    Can be any valid expression as long as it resolves to a string.
      * @param mixed|self $substringExpression Can be any valid expression as long as it resolves to a string.
-     * @param int|null $start An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param int|null $end An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $start               An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $end                 An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      *
      * @return $this
      */
@@ -703,11 +701,10 @@ public function indexOfBytes($stringExpression, $substringExpression, $start = n
      * not found, returns -1.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfCP/
-     * @since 1.5
-     * @param mixed|self $stringExpression Can be any valid expression as long as it resolves to a string.
+     * @param mixed|self $stringExpression    Can be any valid expression as long as it resolves to a string.
      * @param mixed|self $substringExpression Can be any valid expression as long as it resolves to a string.
-     * @param int|null $start An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param int|null $end An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $start               An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $end                 An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      *
      * @return $this
      */
@@ -734,7 +731,6 @@ public function indexOfCP($stringExpression, $substringExpression, $start = null
      * @param mixed|self $expression
      * @return $this
      *
-     * @since 1.3
      */
     public function isArray($expression)
     {
@@ -748,7 +744,6 @@ public function isArray($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoDayOfWeek/
-     * @since 1.5
      * @param mixed|self $expression
      * @return $this
      */
@@ -766,7 +761,6 @@ public function isoDayOfWeek($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoWeek/
-     * @since 1.5
      * @param mixed|self $expression
      * @return $this
      */
@@ -784,7 +778,6 @@ public function isoWeek($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoWeek/
-     * @since 1.5
      * @param mixed|self $expression
      * @return $this
      */
@@ -845,7 +838,6 @@ public function literal($value)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function ln($number)
     {
@@ -866,7 +858,6 @@ public function ln($number)
      * @param mixed|self $base
      * @return $this
      *
-     * @since 1.3
      */
     public function log($number, $base)
     {
@@ -883,7 +874,6 @@ public function log($number, $base)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function log10($number)
     {
@@ -927,7 +917,7 @@ public function lte($expression1, $expression2)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/map/
      * @param mixed|self $input An expression that resolves to an array.
-     * @param string $as        The variable name for the items in the input array. The in expression accesses each item in the input array by this variable.
+     * @param string     $as    The variable name for the items in the input array. The in expression accesses each item in the input array by this variable.
      * @param mixed|self $in    The expression to apply to each item in the input array. The expression accesses the item by its variable name.
      * @return $this
      */
@@ -1088,7 +1078,6 @@ public function not($expression)
      * @param mixed|self $exponent
      * @return $this
      *
-     * @since 1.3
      */
     public function pow($number, $exponent)
     {
@@ -1114,10 +1103,9 @@ public function push($expression)
      * $range generates the sequence from the specified starting number by successively incrementing the starting number by the specified step value up to but not including the end point.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/range/
-     * @since 1.5
      * @param mixed|self $start An integer that specifies the start of the sequence. Can be any valid expression that resolves to an integer.
-     * @param mixed|self $end An integer that specifies the exclusive upper limit of the sequence. Can be any valid expression that resolves to an integer.
-     * @param mixed|self $step Optional. An integer that specifies the increment value. Can be any valid expression that resolves to a non-zero integer. Defaults to 1.
+     * @param mixed|self $end   An integer that specifies the exclusive upper limit of the sequence. Can be any valid expression that resolves to an integer.
+     * @param mixed|self $step  Optional. An integer that specifies the increment value. Can be any valid expression that resolves to a non-zero integer. Defaults to 1.
      * @return $this
      */
     public function range($start, $end, $step = 1)
@@ -1130,10 +1118,9 @@ public function range($start, $end, $step = 1)
      * a single value.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/reduce/
-     * @since 1.5
-     * @param mixed|self $input Can be any valid expression that resolves to an array.
+     * @param mixed|self $input        Can be any valid expression that resolves to an array.
      * @param mixed|self $initialValue The initial cumulative value set before in is applied to the first element of the input array.
-     * @param mixed|self $in A valid expression that $reduce applies to each element in the input array in left-to-right order. Wrap the input value with $reverseArray to yield the equivalent of applying the combining expression from right-to-left.
+     * @param mixed|self $in           A valid expression that $reduce applies to each element in the input array in left-to-right order. Wrap the input value with $reverseArray to yield the equivalent of applying the combining expression from right-to-left.
      * @return $this
      */
     public function reduce($input, $initialValue, $in)
@@ -1146,7 +1133,6 @@ public function reduce($input, $initialValue, $in)
      * elements in reverse order.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/reverseArray/
-     * @since 1.5
      * @param mixed|self $expression
      * @return $this
      */
@@ -1271,12 +1257,11 @@ public function size($expression)
      * Returns a subset of an array.
      *
      * @see https://docs.mongodb.org/manual/reference/operator/aggregation/slice/
-     * @param mixed|self $array
-     * @param mixed|self $n
+     * @param mixed|self      $array
+     * @param mixed|self      $n
      * @param mixed|self|null $position
      * @return $this
      *
-     * @since 1.3
      */
     public function slice($array, $n, $position = null)
     {
@@ -1295,8 +1280,7 @@ public function slice($array, $n, $position = null)
      * returns the original string as the only element of an array.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/split/
-     * @since 1.5
-     * @param mixed|self $string The string to be split. Can be any valid expression as long as it resolves to a string.
+     * @param mixed|self $string    The string to be split. Can be any valid expression as long as it resolves to a string.
      * @param mixed|self $delimiter The delimiter to use when splitting the string expression. Can be any valid expression as long as it resolves to a string.
      *
      * @return $this
@@ -1332,7 +1316,6 @@ public function sqrt($expression)
      * @param mixed|self ...$expressions Additional samples
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevPop($expression1, ...$expressions)
     {
@@ -1351,7 +1334,6 @@ public function stdDevPop($expression1, ...$expressions)
      * @param mixed|self ...$expressions Additional samples
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevSamp($expression1, ...$expressions)
     {
@@ -1382,7 +1364,6 @@ public function strcasecmp($expression1, $expression2)
      * Returns the number of UTF-8 encoded bytes in the specified string.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/strLenBytes/
-     * @since 1.5
      * @param mixed|self $string
      *
      * @return $this
@@ -1396,7 +1377,6 @@ public function strLenBytes($string)
      * Returns the number of UTF-8 code points in the specified string.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/strLenCP/
-     * @since 1.5
      * @param mixed|self $string
      *
      * @return $this
@@ -1431,10 +1411,9 @@ public function substr($string, $start, $length)
      * specified.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/substrBytes/
-     * @since 1.5
      * @param mixed|self $string The string from which the substring will be extracted. Can be any valid expression as long as it resolves to a string.
-     * @param mixed|self $start Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
-     * @param mixed|self $count Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|self $start  Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|self $count  Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
      *
      * @return $this
      */
@@ -1451,10 +1430,9 @@ public function substrBytes($string, $start, $count)
      * specified.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/substrBytes/
-     * @since 1.5
      * @param mixed|self $string The string from which the substring will be extracted. Can be any valid expression as long as it resolves to a string.
-     * @param mixed|self $start Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
-     * @param mixed|self $count Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|self $start  Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|self $count  Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
      *
      * @return $this
      */
@@ -1531,7 +1509,6 @@ public function toUpper($expression)
      * @param mixed|self $number
      * @return $this
      *
-     * @since 1.3
      */
     public function trunc($number)
     {
@@ -1544,7 +1521,6 @@ public function trunc($number)
      * The argument can be any valid expression.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/type/
-     * @since 1.5
      * @param mixed|self $expression
      *
      * @return $this
@@ -1588,10 +1564,9 @@ public function year($expression)
      * input array, the first element of the second input array, etc.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/zip/
-     * @since 1.5
-     * @param mixed|self $inputs An array of expressions that resolve to arrays. The elements of these input arrays combine to form the arrays of the output array.
-     * @param bool|null $useLongestLength A boolean which specifies whether the length of the longest array determines the number of arrays in the output array.
-     * @param mixed|self|null $defaults An array of default element values to use if the input arrays have different lengths. You must specify useLongestLength: true along with this field, or else $zip will return an error.
+     * @param mixed|self      $inputs           An array of expressions that resolve to arrays. The elements of these input arrays combine to form the arrays of the output array.
+     * @param bool|null       $useLongestLength A boolean which specifies whether the length of the longest array determines the number of arrays in the output array.
+     * @param mixed|self|null $defaults         An array of default element values to use if the input arrays have different lengths. You must specify useLongestLength: true along with this field, or else $zip will return an error.
      * @return $this
      */
     public function zip($inputs, $useLongestLength = null, $defaults = null)
@@ -1627,7 +1602,7 @@ private function ensureArray($expression)
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister()
     {
@@ -1640,7 +1615,7 @@ private function getDocumentPersister()
      * If there is a current field, the operator will be set on it; otherwise,
      * the operator is set at the top level of the query.
      *
-     * @param string $operator
+     * @param string            $operator
      * @param array|self[]|self $expression
      * @return $this
      */
@@ -1664,7 +1639,7 @@ private function operator($operator, $expression)
      */
     private function requiresCurrentField($method = null)
     {
-        if ( ! $this->currentField) {
+        if (! $this->currentField) {
             throw new \LogicException(($method ?: 'This method') . ' requires you set a current field using field().');
         }
     }
@@ -1732,5 +1707,4 @@ public function then($expression)
 
         return $this;
     }
-
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage.php
index e439fde92b..df7724a0cb 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation;
 
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
@@ -8,8 +10,6 @@
 /**
  * Fluent interface for building aggregation pipelines.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  * @internal
  */
 abstract class Stage
@@ -19,9 +19,6 @@ abstract class Stage
      */
     protected $builder;
 
-    /**
-     * @param Builder $builder
-     */
     public function __construct(Builder $builder)
     {
         $this->builder = $builder;
@@ -92,8 +89,6 @@ public function bucketAuto()
      * the pipeline returns an error.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/geoNear/
-     * @since 1.5
-     *
      * @return Stage\CollStats
      */
     public function collStats()
@@ -135,7 +130,7 @@ public function facet()
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/geoNear/
      *
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return Stage\GeoNear
      */
     public function geoNear($x, $y = null)
@@ -198,7 +193,7 @@ public function indexStats()
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/limit/
      *
-     * @param integer $limit
+     * @param int $limit
      * @return Stage\Limit
      */
     public function limit($limit)
@@ -298,7 +293,7 @@ public function replaceRoot($expression = null)
      *
      * @see https://docs.mongodb.org/manual/reference/operator/aggregation/sample/
      *
-     * @param integer $size
+     * @param int $size
      * @return Stage\Sample
      */
     public function sample($size)
@@ -312,7 +307,7 @@ public function sample($size)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/skip/
      *
-     * @param integer $skip
+     * @param int $skip
      * @return Stage\Skip
      */
     public function skip($skip)
@@ -343,7 +338,7 @@ public function sortByCount($expression)
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/sort/
      *
      * @param array|string $fieldName Field name or array of field/order pairs
-     * @param integer|string $order   Field order (if one field is specified)
+     * @param int|string   $order     Field order (if one field is specified)
      * @return Stage\Sort
      */
     public function sort($fieldName, $order = null)
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AbstractBucket.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AbstractBucket.php
index 7f6b5475d4..1bb990b0c7 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AbstractBucket.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AbstractBucket.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -7,14 +9,17 @@
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Types\Type;
+use function array_map;
+use function is_array;
+use function is_string;
+use function substr;
 
 /**
  * Abstract class with common functionality for $bucket and $bucketAuto stages
  *
  * @internal
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 abstract class AbstractBucket extends Stage
 {
@@ -102,7 +107,7 @@ private function convertExpression($expression)
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AddFields.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AddFields.php
index 6cd1d014a3..445925d1d3 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AddFields.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/AddFields.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 /**
  * Fluent interface for adding a $addFields stage to an aggregation pipeline.
  *
- * @author Boris Guéry <guery.b@gmail.com>
  */
 final class AddFields extends Operator
 {
@@ -15,7 +16,7 @@ final class AddFields extends Operator
     public function getExpression()
     {
         return [
-            '$addFields' => $this->expr->getExpression()
+            '$addFields' => $this->expr->getExpression(),
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket.php
index f72dd8f31f..bb4ee2d58c 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 class Bucket extends AbstractBucket
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/AbstractOutput.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/AbstractOutput.php
index ab33c00e0a..618a895dd9 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/AbstractOutput.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/AbstractOutput.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage\Bucket;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -10,8 +12,6 @@
  * Abstract class with common functionality for output objects in bucket stages
  *
  * @internal
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 abstract class AbstractOutput extends Stage
 {
@@ -25,10 +25,6 @@ abstract class AbstractOutput extends Stage
      */
     private $expr;
 
-    /**
-     * @param Builder $builder
-     * @param Stage\AbstractBucket $bucket
-     */
     public function __construct(Builder $builder, Stage\AbstractBucket $bucket)
     {
         parent::__construct($builder);
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketAutoOutput.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketAutoOutput.php
index 5a5eb24951..cc46f15f85 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketAutoOutput.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketAutoOutput.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage\Bucket;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,15 +10,9 @@
 /**
  * Fluent interface for adding an output specification to a bucket stage.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 class BucketAutoOutput extends AbstractOutput
 {
-    /**
-     * @param Builder $builder
-     * @param Stage\BucketAuto $bucket
-     */
     public function __construct(Builder $builder, Stage\BucketAuto $bucket)
     {
         parent::__construct($builder, $bucket);
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketOutput.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketOutput.php
index 75c6f39c3c..ad23487597 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketOutput.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Bucket/BucketOutput.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage\Bucket;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -9,15 +11,9 @@
 /**
  * Fluent interface for adding an output specification to a bucket stage.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 class BucketOutput extends AbstractOutput
 {
-    /**
-     * @param Builder $builder
-     * @param Stage\Bucket $bucket
-     */
     public function __construct(Builder $builder, Stage\Bucket $bucket)
     {
         parent::__construct($builder, $bucket);
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/BucketAuto.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/BucketAuto.php
index 77cd311c6e..e9678a197f 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/BucketAuto.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/BucketAuto.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 class BucketAuto extends AbstractBucket
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/CollStats.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/CollStats.php
index bb66ed772c..5b7625d41f 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/CollStats.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/CollStats.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,14 +10,12 @@
 /**
  * Fluent interface for adding a $collStats stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 class CollStats extends Stage
 {
-    const LATENCY_STATS_NONE = 0;
-    const LATENCY_STATS_SIMPLE = 1;
-    const LATENCY_STATS_HISTOGRAMS = 2;
+    public const LATENCY_STATS_NONE = 0;
+    public const LATENCY_STATS_SIMPLE = 1;
+    public const LATENCY_STATS_HISTOGRAMS = 2;
 
     /**
      * @var int
@@ -27,9 +27,6 @@ class CollStats extends Stage
      */
     private $storageStats = false;
 
-    /**
-     * @param Builder $builder
-     */
     public function __construct(Builder $builder)
     {
         parent::__construct($builder);
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Count.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Count.php
index 8e26b624b0..c6b8988d1d 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Count.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Count.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,8 +10,6 @@
 /**
  * Fluent interface for adding a $count stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 class Count extends Stage
 {
@@ -19,7 +19,6 @@ class Count extends Stage
     private $fieldName;
 
     /**
-     * @param Builder $builder
      * @param string $fieldName
      */
     public function __construct(Builder $builder, $fieldName)
@@ -35,7 +34,7 @@ public function __construct(Builder $builder, $fieldName)
     public function getExpression()
     {
         return [
-            '$count' => $this->fieldName
+            '$count' => $this->fieldName,
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Facet.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Facet.php
index 10c3410af7..99e9052597 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Facet.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Facet.php
@@ -1,15 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
+use function array_map;
 
 /**
  * Fluent interface for adding a $facet stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.5
  */
 class Facet extends Stage
 {
@@ -29,7 +30,9 @@ class Facet extends Stage
     public function getExpression()
     {
         return [
-            '$facet' => array_map(function (Builder $builder) { return $builder->getPipeline(); }, $this->pipelines),
+            '$facet' => array_map(function (Builder $builder) {
+                return $builder->getPipeline();
+            }, $this->pipelines),
         ];
     }
 
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GeoNear.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GeoNear.php
index 7e82f6a0ff..dc4c39b17b 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GeoNear.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GeoNear.php
@@ -1,15 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use GeoJson\Geometry\Point;
+use function is_array;
 
 /**
  * Fluent interface for adding a $geoNear stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class GeoNear extends Match
 {
@@ -44,24 +45,23 @@ class GeoNear extends Match
     private $near;
 
     /**
-     * @var integer
+     * @var int
      */
     private $num;
 
     /**
-     * @var boolean
+     * @var bool
      */
     private $spherical = false;
 
     /**
-     * @var boolean
+     * @var bool
      */
     private $uniqueDocs;
 
     /**
-     * @param Builder $builder
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      */
     public function __construct(Builder $builder, $x, $y = null)
     {
@@ -79,20 +79,18 @@ public function getExpression()
             'near' => $this->near,
             'spherical' => $this->spherical,
             'distanceField' => $this->distanceField,
-            'query' => $this->query->getQuery()
+            'query' => $this->query->getQuery(),
         ];
 
         foreach (['distanceMultiplier', 'includeLocs', 'maxDistance', 'minDistance', 'num', 'uniqueDocs'] as $option) {
-            if ( ! $this->$option) {
+            if (! $this->$option) {
                 continue;
             }
 
             $geoNear[$option] = $this->$option;
         }
 
-        return [
-            '$geoNear' => $geoNear
-        ];
+        return ['$geoNear' => $geoNear];
     }
 
     /**
@@ -137,7 +135,7 @@ public function includeLocs($includeLocs)
     /**
      * The maximum number of documents to return.
      *
-     * @param integer $limit
+     * @param int $limit
      * @return $this
      */
     public function limit($limit)
@@ -164,7 +162,6 @@ public function maxDistance($maxDistance)
      * @param float $minDistance
      * @return $this
      *
-     * @since 1.3
      */
     public function minDistance($minDistance)
     {
@@ -182,7 +179,7 @@ public function minDistance($minDistance)
      * used, the "spherical" option will default to true.
      *
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return $this
      */
     public function near($x, $y = null)
@@ -200,12 +197,12 @@ public function near($x, $y = null)
     /**
      * The maximum number of documents to return.
      *
-     * @param integer $num
+     * @param int $num
      * @return $this
      */
     public function num($num)
     {
-        $this->num = (integer) $num;
+        $this->num = (int) $num;
 
         return $this;
     }
@@ -213,12 +210,12 @@ public function num($num)
     /**
      * Required if using a 2dsphere index. Determines how MongoDB calculates the distance.
      *
-     * @param boolean $spherical
+     * @param bool $spherical
      * @return $this
      */
     public function spherical($spherical = true)
     {
-        $this->spherical = (boolean) $spherical;
+        $this->spherical = (bool) $spherical;
 
         return $this;
     }
@@ -226,12 +223,12 @@ public function spherical($spherical = true)
     /**
      * If this value is true, the query returns a matching document once, even if more than one of the document’s location fields match the query.
      *
-     * @param boolean $uniqueDocs
+     * @param bool $uniqueDocs
      * @return $this
      */
     public function uniqueDocs($uniqueDocs = true)
     {
-        $this->uniqueDocs = (boolean) $uniqueDocs;
+        $this->uniqueDocs = (bool) $uniqueDocs;
 
         return $this;
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup.php
index d3a30ea77a..90ed370f21 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\Common\Persistence\Mapping\MappingException as BaseMappingException;
@@ -9,7 +11,12 @@
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Types\Type;
+use function array_map;
+use function is_array;
+use function is_string;
+use function substr;
 
 class GraphLookup extends Stage
 {
@@ -69,11 +76,8 @@ class GraphLookup extends Stage
     private $targetClass;
 
     /**
-     * @param Builder $builder
      * @param string $from Target collection for the $graphLookup operation to
      * search, recursively matching the connectFromField to the connectToField.
-     * @param DocumentManager $documentManager
-     * @param ClassMetadata $class
      */
     public function __construct(Builder $builder, $from, DocumentManager $documentManager, ClassMetadata $class)
     {
@@ -116,13 +120,13 @@ public function alias($alias)
     public function connectFromField($connectFromField)
     {
         // No targetClass mapping - simply use field name as is
-        if ( ! $this->targetClass) {
+        if (! $this->targetClass) {
             $this->connectFromField = $connectFromField;
             return $this;
         }
 
         // connectFromField doesn't have to be a reference - in this case, just convert the field name
-        if ( ! $this->targetClass->hasReference($connectFromField)) {
+        if (! $this->targetClass->hasReference($connectFromField)) {
             $this->connectFromField = $this->convertTargetFieldName($connectFromField);
             return $this;
         }
@@ -281,7 +285,7 @@ public function startWith($expression)
      */
     private function fromReference($fieldName)
     {
-        if ( ! $this->class->hasReference($fieldName)) {
+        if (! $this->class->hasReference($fieldName)) {
             MappingException::referenceMappingNotFound($this->class->name, $fieldName);
         }
 
@@ -330,7 +334,7 @@ private function convertTargetFieldName($fieldName)
             return array_map([$this, 'convertTargetFieldName'], $fieldName);
         }
 
-        if ( ! $this->targetClass) {
+        if (! $this->targetClass) {
             return $fieldName;
         }
 
@@ -338,8 +342,7 @@ private function convertTargetFieldName($fieldName)
     }
 
     /**
-     * @param ClassMetadata $class
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister(ClassMetadata $class)
     {
@@ -348,7 +351,7 @@ private function getDocumentPersister(ClassMetadata $class)
 
     private function getReferencedFieldName($fieldName, array $mapping)
     {
-        if ( ! $mapping['isOwningSide']) {
+        if (! $mapping['isOwningSide']) {
             if (isset($mapping['repositoryMethod']) || ! isset($mapping['mappedBy'])) {
                 throw MappingException::repositoryMethodLookupNotAllowed($this->class->name, $fieldName);
             }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup/Match.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup/Match.php
index 5f936a09c0..65541e8be8 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup/Match.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/GraphLookup/Match.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage\GraphLookup;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -14,10 +16,6 @@ class Match extends BaseMatch
      */
     private $graphLookup;
 
-    /**
-     * @param Builder $builder
-     * @param GraphLookup $graphLookup
-     */
     public function __construct(Builder $builder, GraphLookup $graphLookup)
     {
         parent::__construct($builder);
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Group.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Group.php
index 6303655592..b1fc9c3199 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Group.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Group.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,8 +10,6 @@
 /**
  * Fluent interface for adding a $group stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Group extends Operator
 {
@@ -34,7 +34,7 @@ public function __construct(Builder $builder)
     public function getExpression()
     {
         return [
-            '$group' => $this->expr->getExpression()
+            '$group' => $this->expr->getExpression(),
         ];
     }
 
@@ -195,7 +195,6 @@ public function push($expression)
      * @param mixed|Expr $expression
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevPop($expression)
     {
@@ -214,7 +213,6 @@ public function stdDevPop($expression)
      * @param mixed|Expr $expression
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevSamp($expression)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/IndexStats.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/IndexStats.php
index 6a71441898..8b427c6a8a 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/IndexStats.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/IndexStats.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
@@ -7,8 +9,6 @@
 /**
  * Fluent interface for adding a $indexStats stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.3
  */
 class IndexStats extends Stage
 {
@@ -18,7 +18,7 @@ class IndexStats extends Stage
     public function getExpression()
     {
         return [
-            '$indexStats' => new \stdClass()
+            '$indexStats' => new \stdClass(),
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Limit.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Limit.php
index 543ccc2589..efb45a52f8 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Limit.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Limit.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,25 +10,22 @@
 /**
  * Fluent interface for adding a $limit stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Limit extends Stage
 {
     /**
-     * @var integer
+     * @var int
      */
     private $limit;
 
     /**
-     * @param Builder $builder
-     * @param integer $limit
+     * @param int $limit
      */
     public function __construct(Builder $builder, $limit)
     {
         parent::__construct($builder);
 
-        $this->limit = (integer) $limit;
+        $this->limit = (int) $limit;
     }
 
     /**
@@ -35,7 +34,7 @@ public function __construct(Builder $builder, $limit)
     public function getExpression()
     {
         return [
-            '$limit' => $this->limit
+            '$limit' => $this->limit,
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Lookup.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Lookup.php
index 8f1c711f01..b53dfa4397 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Lookup.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Lookup.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\Common\Persistence\Mapping\MappingException as BaseMappingException;
@@ -8,6 +10,7 @@
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 
 /**
  * Fluent interface for building aggregation pipelines.
@@ -50,10 +53,7 @@ class Lookup extends Stage
     private $as;
 
     /**
-     * @param Builder $builder
      * @param string $from
-     * @param DocumentManager $documentManager
-     * @param ClassMetadata $class
      */
     public function __construct(Builder $builder, $from, DocumentManager $documentManager, ClassMetadata $class)
     {
@@ -130,7 +130,7 @@ public function getExpression()
                 'localField' => $this->localField,
                 'foreignField' => $this->foreignField,
                 'as' => $this->as,
-            ]
+            ],
         ];
     }
 
@@ -170,9 +170,9 @@ public function foreignField($foreignField)
         return $this;
     }
 
-    protected function prepareFieldName($fieldName, ClassMetadata $class = null)
+    protected function prepareFieldName($fieldName, ?ClassMetadata $class = null)
     {
-        if ( ! $class) {
+        if (! $class) {
             return $fieldName;
         }
 
@@ -237,7 +237,7 @@ private function fromReference($fieldName)
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister(ClassMetadata $class)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Match.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Match.php
index f1b32d9820..ff68f44aed 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Match.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Match.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
 use Doctrine\ODM\MongoDB\Query\Expr;
 use GeoJson\Geometry\Geometry;
+use function func_get_args;
 
 /**
  * Fluent interface for building aggregation pipelines.
@@ -159,12 +162,12 @@ public function equals($value)
      *
      * @see Expr::exists()
      * @see http://docs.mongodb.org/manual/reference/operator/exists/
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function exists($bool)
     {
-        $this->query->exists((boolean) $bool);
+        $this->query->exists((bool) $bool);
 
         return $this;
     }
@@ -220,7 +223,6 @@ public function geoIntersects($geometry)
      *
      * @see Expr::geoWithin()
      * @see http://docs.mongodb.org/manual/reference/operator/geoWithin/
-     * @param Geometry $geometry
      * @return $this
      */
     public function geoWithin(Geometry $geometry)
@@ -306,9 +308,9 @@ public function geoWithinCenterSphere($x, $y, $radius)
      *
      * @see Expr::geoWithinPolygon()
      * @see http://docs.mongodb.org/manual/reference/operator/polygon/
-     * @param array $point1 First point of the polygon
-     * @param array $point2 Second point of the polygon
-     * @param array $point3 Third point of the polygon
+     * @param array $point1    First point of the polygon
+     * @param array $point2    Second point of the polygon
+     * @param array $point3    Third point of the polygon
      * @param array ...$points Additional points of the polygon
      * @return $this
      */
@@ -481,8 +483,8 @@ public function minDistance($minDistance)
      *
      * @see Expr::mod()
      * @see http://docs.mongodb.org/manual/reference/operator/mod/
-     * @param float|integer $divisor
-     * @param float|integer $remainder
+     * @param float|int $divisor
+     * @param float|int $remainder
      * @return $this
      */
     public function mod($divisor, $remainder = 0)
@@ -574,12 +576,12 @@ public function references($document)
      *
      * @see Expr::size()
      * @see http://docs.mongodb.org/manual/reference/operator/size/
-     * @param integer $size
+     * @param int $size
      * @return $this
      */
     public function size($size)
     {
-        $this->query->size((integer) $size);
+        $this->query->size((int) $size);
 
         return $this;
     }
@@ -608,7 +610,7 @@ public function text($search)
      *
      * @see Expr::type()
      * @see http://docs.mongodb.org/manual/reference/operator/type/
-     * @param integer $type
+     * @param int $type
      * @return $this
      */
     public function type($type)
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Operator.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Operator.php
index 8874e6c3f1..02aef11848 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Operator.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Operator.php
@@ -1,16 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
+use function func_get_args;
 
 /**
  * Fluent interface for adding operators to aggregation stages.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  * @method $this switch()
  * @method $this case(mixed|Expr $expression)
  * @method $this then(mixed|Expr $expression)
@@ -35,7 +36,7 @@ public function __construct(Builder $builder)
 
     /**
      * @param string $method
-     * @param array $args
+     * @param array  $args
      * @return $this
      */
     public function __call($method, $args)
@@ -56,7 +57,6 @@ public function __call($method, $args)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function abs($number)
     {
@@ -168,7 +168,6 @@ public function anyElementTrue($expression)
      * @param mixed|Expr $index
      * @return $this
      *
-     * @since 1.3
      */
     public function arrayElemAt($array, $index)
     {
@@ -188,7 +187,6 @@ public function arrayElemAt($array, $index)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function ceil($number)
     {
@@ -250,7 +248,6 @@ public function concat($expression1, $expression2, ...$expressions)
      * @param mixed|Expr ...$arrays Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function concatArrays($array1, $array2, ...$arrays)
     {
@@ -288,7 +285,7 @@ public function cond($if, $then, $else)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/dateToString/
      * @see Expr::dateToString
-     * @param string $format
+     * @param string     $format
      * @param mixed|Expr $expression
      * @return $this
      */
@@ -397,7 +394,6 @@ public function eq($expression1, $expression2)
      * @param mixed|Expr $exponent
      * @return $this
      *
-     * @since 1.3
      */
     public function exp($exponent)
     {
@@ -448,7 +444,6 @@ public function field($fieldName)
      * @param mixed|Expr $cond
      * @return $this
      *
-     * @since 1.3
      */
     public function filter($input, $as, $cond)
     {
@@ -468,7 +463,6 @@ public function filter($input, $as, $cond)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function floor($number)
     {
@@ -538,7 +532,6 @@ public function hour($expression)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/in/
      * @see Expr::in
-     * @since 1.5
      * @param mixed|Expr $expression
      * @param mixed|Expr $arrayExpression
      * @return $this
@@ -557,11 +550,10 @@ public function in($expression, $arrayExpression)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfArray/
      * @see Expr::indexOfArray
-     * @since 1.5
-     * @param mixed|Expr $arrayExpression Can be any valid expression as long as it resolves to an array.
+     * @param mixed|Expr $arrayExpression  Can be any valid expression as long as it resolves to an array.
      * @param mixed|Expr $searchExpression Can be any valid expression.
-     * @param mixed|Expr $start Optional. An integer, or a number that can be represented as integers (such as 2.0), that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param mixed|Expr $end An integer, or a number that can be represented as integers (such as 2.0), that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param mixed|Expr $start            Optional. An integer, or a number that can be represented as integers (such as 2.0), that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param mixed|Expr $end              An integer, or a number that can be represented as integers (such as 2.0), that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      * @return $this
      */
     public function indexOfArray($arrayExpression, $searchExpression, $start = null, $end = null)
@@ -577,11 +569,10 @@ public function indexOfArray($arrayExpression, $searchExpression, $start = null,
      * found, returns -1.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfBytes/
-     * @since 1.5
-     * @param mixed|Expr $stringExpression Can be any valid expression as long as it resolves to a string.
+     * @param mixed|Expr $stringExpression    Can be any valid expression as long as it resolves to a string.
      * @param mixed|Expr $substringExpression Can be any valid expression as long as it resolves to a string.
-     * @param int|null $start An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param int|null $end An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $start               An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $end                 An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      *
      * @return $this
      */
@@ -598,11 +589,10 @@ public function indexOfBytes($stringExpression, $substringExpression, $start = n
      * not found, returns -1.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfCP/
-     * @since 1.5
-     * @param mixed|Expr $stringExpression Can be any valid expression as long as it resolves to a string.
+     * @param mixed|Expr $stringExpression    Can be any valid expression as long as it resolves to a string.
      * @param mixed|Expr $substringExpression Can be any valid expression as long as it resolves to a string.
-     * @param int|null $start An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
-     * @param int|null $end An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $start               An integral number that specifies the starting index position for the search. Can be any valid expression that resolves to a non-negative integral number.
+     * @param int|null   $end                 An integral number that specifies the ending index position for the search. Can be any valid expression that resolves to a non-negative integral number.
      *
      * @return $this
      */
@@ -644,7 +634,6 @@ public function ifNull($expression, $replacementExpression)
      * @param mixed|Expr $expression
      * @return $this
      *
-     * @since 1.3
      */
     public function isArray($expression)
     {
@@ -660,7 +649,6 @@ public function isArray($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoDayOfWeek/
-     * @since 1.5
      * @param mixed|Expr $expression
      * @return $this
      */
@@ -680,7 +668,6 @@ public function isoDayOfWeek($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoWeek/
-     * @since 1.5
      * @param mixed|Expr $expression
      * @return $this
      */
@@ -700,7 +687,6 @@ public function isoWeek($expression)
      * The argument can be any expression as long as it resolves to a date.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/isoWeek/
-     * @since 1.5
      * @param mixed|Expr $expression
      * @return $this
      */
@@ -756,7 +742,6 @@ public function literal($value)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function ln($number)
     {
@@ -780,7 +765,6 @@ public function ln($number)
      * @param mixed|Expr $base
      * @return $this
      *
-     * @since 1.3
      */
     public function log($number, $base)
     {
@@ -802,7 +786,6 @@ public function log($number, $base)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function log10($number)
     {
@@ -854,7 +837,7 @@ public function lte($expression1, $expression2)
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/map/
      * @see Expr::map
      * @param mixed|Expr $input An expression that resolves to an array.
-     * @param string $as        The variable name for the items in the input array. The in expression accesses each item in the input array by this variable.
+     * @param string     $as    The variable name for the items in the input array. The in expression accesses each item in the input array by this variable.
      * @param mixed|Expr $in    The expression to apply to each item in the input array. The expression accesses the item by its variable name.
      * @return $this
      */
@@ -1016,7 +999,6 @@ public function not($expression)
      * @param mixed|Expr $exponent
      * @return $this
      *
-     * @since 1.3
      */
     public function pow($number, $exponent)
     {
@@ -1032,10 +1014,9 @@ public function pow($number, $exponent)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/range/
      * @see Expr::range
-     * @since 1.5
      * @param mixed|Expr $start An integer that specifies the start of the sequence. Can be any valid expression that resolves to an integer.
-     * @param mixed|Expr $end An integer that specifies the exclusive upper limit of the sequence. Can be any valid expression that resolves to an integer.
-     * @param mixed|Expr $step Optional. An integer that specifies the increment value. Can be any valid expression that resolves to a non-zero integer. Defaults to 1.
+     * @param mixed|Expr $end   An integer that specifies the exclusive upper limit of the sequence. Can be any valid expression that resolves to an integer.
+     * @param mixed|Expr $step  Optional. An integer that specifies the increment value. Can be any valid expression that resolves to a non-zero integer. Defaults to 1.
      * @return $this
      */
     public function range($start, $end, $step = 1)
@@ -1051,10 +1032,9 @@ public function range($start, $end, $step = 1)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/reduce/
      * @see Expr::reduce
-     * @since 1.5
-     * @param mixed|Expr $input Can be any valid expression that resolves to an array.
+     * @param mixed|Expr $input        Can be any valid expression that resolves to an array.
      * @param mixed|Expr $initialValue The initial cumulative value set before in is applied to the first element of the input array.
-     * @param mixed|Expr $in A valid expression that $reduce applies to each element in the input array in left-to-right order. Wrap the input value with $reverseArray to yield the equivalent of applying the combining expression from right-to-left.
+     * @param mixed|Expr $in           A valid expression that $reduce applies to each element in the input array in left-to-right order. Wrap the input value with $reverseArray to yield the equivalent of applying the combining expression from right-to-left.
      * @return $this
      */
     public function reduce($input, $initialValue, $in)
@@ -1070,7 +1050,6 @@ public function reduce($input, $initialValue, $in)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/reverseArray/
      * @see Expr::reverseArray
-     * @since 1.5
      * @param mixed|Expr $expression
      * @return $this
      */
@@ -1220,12 +1199,11 @@ public function size($expression)
      *
      * @see https://docs.mongodb.org/manual/reference/operator/aggregation/slice/
      * @see Expr::slice
-     * @param mixed|Expr $array
-     * @param mixed|Expr $n
+     * @param mixed|Expr      $array
+     * @param mixed|Expr      $n
      * @param mixed|Expr|null $position
      * @return $this
      *
-     * @since 1.3
      */
     public function slice($array, $n, $position = null)
     {
@@ -1242,8 +1220,7 @@ public function slice($array, $n, $position = null)
      * returns the original string as the only element of an array.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/split/
-     * @since 1.5
-     * @param mixed|Expr $string The string to be split. Can be any valid expression as long as it resolves to a string.
+     * @param mixed|Expr $string    The string to be split. Can be any valid expression as long as it resolves to a string.
      * @param mixed|Expr $delimiter The delimiter to use when splitting the string expression. Can be any valid expression as long as it resolves to a string.
      *
      * @return $this
@@ -1299,7 +1276,6 @@ public function strcasecmp($expression1, $expression2)
      * Returns the number of UTF-8 encoded bytes in the specified string.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/strLenBytes/
-     * @since 1.5
      * @param mixed|Expr $string
      *
      * @return $this
@@ -1315,7 +1291,6 @@ public function strLenBytes($string)
      * Returns the number of UTF-8 code points in the specified string.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/strLenCP/
-     * @since 1.5
      * @param mixed|Expr $string
      *
      * @return $this
@@ -1355,10 +1330,9 @@ public function substr($string, $start, $length)
      * specified.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/substrBytes/
-     * @since 1.5
      * @param mixed|Expr $string The string from which the substring will be extracted. Can be any valid expression as long as it resolves to a string.
-     * @param mixed|Expr $start Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
-     * @param mixed|Expr $count Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|Expr $start  Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|Expr $count  Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
      *
      * @return $this
      */
@@ -1377,10 +1351,9 @@ public function substrBytes($string, $start, $count)
      * specified.
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/substrBytes/
-     * @since 1.5
      * @param mixed|Expr $string The string from which the substring will be extracted. Can be any valid expression as long as it resolves to a string.
-     * @param mixed|Expr $start Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
-     * @param mixed|Expr $count Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|Expr $start  Indicates the starting point of the substring. Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
+     * @param mixed|Expr $count  Can be any valid expression as long as it resolves to a non-negative integer or number that can be represented as an integer.
      *
      * @return $this
      */
@@ -1455,7 +1428,6 @@ public function toUpper($expression)
      * @param mixed|Expr $number
      * @return $this
      *
-     * @since 1.3
      */
     public function trunc($number)
     {
@@ -1470,7 +1442,6 @@ public function trunc($number)
      * The argument can be any valid expression.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/aggregation/type/
-     * @since 1.5
      * @param mixed|Expr $expression
      *
      * @return $this
@@ -1523,10 +1494,9 @@ public function year($expression)
      *
      * @see https://docs.mongodb.com/manual/reference/operator/aggregation/zip/
      * @see Expr::zip
-     * @since 1.5
-     * @param mixed|Expr $inputs An array of expressions that resolve to arrays. The elements of these input arrays combine to form the arrays of the output array.
-     * @param bool|null $useLongestLength A boolean which specifies whether the length of the longest array determines the number of arrays in the output array.
-     * @param mixed|Expr|null $defaults An array of default element values to use if the input arrays have different lengths. You must specify useLongestLength: true along with this field, or else $zip will return an error.
+     * @param mixed|Expr      $inputs           An array of expressions that resolve to arrays. The elements of these input arrays combine to form the arrays of the output array.
+     * @param bool|null       $useLongestLength A boolean which specifies whether the length of the longest array determines the number of arrays in the output array.
+     * @param mixed|Expr|null $defaults         An array of default element values to use if the input arrays have different lengths. You must specify useLongestLength: true along with this field, or else $zip will return an error.
      * @return $this
      */
     public function zip($inputs, $useLongestLength = null, $defaults = null)
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Out.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Out.php
index e89771be48..a174669225 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Out.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Out.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\Common\Persistence\Mapping\MappingException as BaseMappingException;
@@ -22,9 +24,7 @@ class Out extends Stage
     private $collection;
 
     /**
-     * @param Builder $builder
      * @param string $collection
-     * @param DocumentManager $documentManager
      */
     public function __construct(Builder $builder, $collection, DocumentManager $documentManager)
     {
@@ -40,7 +40,7 @@ public function __construct(Builder $builder, $collection, DocumentManager $docu
     public function getExpression()
     {
         return [
-            '$out' => $this->collection
+            '$out' => $this->collection,
         ];
     }
 
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Project.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Project.php
index 5e040daa58..630cca3359 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Project.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Project.php
@@ -1,14 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
+use function func_get_args;
 
 /**
  * Fluent interface for adding a $project stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Project extends Operator
 {
@@ -18,7 +19,7 @@ class Project extends Operator
     public function getExpression()
     {
         return [
-            '$project' => $this->expr->getExpression()
+            '$project' => $this->expr->getExpression(),
         ];
     }
 
@@ -33,7 +34,6 @@ public function getExpression()
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function avg($expression1, ...$expressions)
     {
@@ -63,7 +63,6 @@ public function includeFields(array $fields)
      * If you specify the exclusion of a field other than _id, you cannot employ
      * any other $project specification forms.
      *
-     * @since 1.5
      * @param array $fields
      * @return $this
      */
@@ -86,7 +85,6 @@ public function excludeFields(array $fields)
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function max($expression1, ...$expressions)
     {
@@ -105,7 +103,6 @@ public function max($expression1, ...$expressions)
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function min($expression1, ...$expressions)
     {
@@ -125,7 +122,6 @@ public function min($expression1, ...$expressions)
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevPop($expression1, ...$expressions)
     {
@@ -145,7 +141,6 @@ public function stdDevPop($expression1, ...$expressions)
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function stdDevSamp($expression1, ...$expressions)
     {
@@ -165,7 +160,6 @@ public function stdDevSamp($expression1, ...$expressions)
      * @param mixed|Expr ...$expressions Additional expressions
      * @return $this
      *
-     * @since 1.3
      */
     public function sum($expression1, ...$expressions)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Redact.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Redact.php
index 9c0cf95161..f88a71cf56 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Redact.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Redact.php
@@ -1,12 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 /**
  * Fluent interface for adding a $redact stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Redact extends Operator
 {
@@ -16,7 +16,7 @@ class Redact extends Operator
     public function getExpression()
     {
         return [
-            '$redact' => $this->expr->getExpression()
+            '$redact' => $this->expr->getExpression(),
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/ReplaceRoot.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/ReplaceRoot.php
index f6e39f6ea4..40736ea4d7 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/ReplaceRoot.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/ReplaceRoot.php
@@ -1,12 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Types\Type;
+use function array_map;
+use function is_array;
+use function is_string;
+use function substr;
 
 class ReplaceRoot extends Operator
 {
@@ -40,7 +47,7 @@ public function __construct(Builder $builder, DocumentManager $documentManager,
     public function getExpression()
     {
         return [
-            '$replaceRoot' => $this->expression !== null ? $this->convertExpression($this->expression) : $this->expr->getExpression()
+            '$replaceRoot' => $this->expression !== null ? $this->convertExpression($this->expression) : $this->expr->getExpression(),
         ];
     }
 
@@ -56,7 +63,7 @@ private function convertExpression($expression)
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+     * @return DocumentPersister
      */
     private function getDocumentPersister()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sample.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sample.php
index dd0f16a3eb..e2c401be98 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sample.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sample.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,25 +10,22 @@
 /**
  * Fluent interface for adding a $sample stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.3
  */
 class Sample extends Stage
 {
     /**
-     * @var integer
+     * @var int
      */
     private $size;
 
     /**
-     * @param Builder $builder
-     * @param integer $size
+     * @param int $size
      */
     public function __construct(Builder $builder, $size)
     {
         parent::__construct($builder);
 
-        $this->size = (integer) $size;
+        $this->size = (int) $size;
     }
 
     /**
@@ -35,7 +34,7 @@ public function __construct(Builder $builder, $size)
     public function getExpression()
     {
         return [
-            '$sample' => ['size' => $this->size]
+            '$sample' => ['size' => $this->size],
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Skip.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Skip.php
index 5105798721..9379d32c81 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Skip.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Skip.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,25 +10,22 @@
 /**
  * Fluent interface for adding a $skip stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Skip extends Stage
 {
     /**
-     * @var integer
+     * @var int
      */
     private $skip;
 
     /**
-     * @param Builder $builder
-     * @param integer $skip
+     * @param int $skip
      */
     public function __construct(Builder $builder, $skip)
     {
         parent::__construct($builder);
 
-        $this->skip = (integer) $skip;
+        $this->skip = (int) $skip;
     }
 
     /**
@@ -35,7 +34,7 @@ public function __construct(Builder $builder, $skip)
     public function getExpression()
     {
         return [
-            '$skip' => $this->skip
+            '$skip' => $this->skip,
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sort.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sort.php
index e3550578e2..1f627263e4 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sort.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Sort.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
+use function in_array;
+use function is_array;
+use function is_string;
+use function strtolower;
 
 /**
  * Fluent interface for adding a $sort stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Sort extends Stage
 {
@@ -19,9 +23,8 @@ class Sort extends Stage
     private $sort = [];
 
     /**
-     * @param Builder $builder
      * @param array|string $fieldName Field name or array of field/order pairs
-     * @param int|string $order       Field order (if one field is specified)
+     * @param int|string   $order     Field order (if one field is specified)
      */
     public function __construct(Builder $builder, $fieldName, $order = null)
     {
@@ -50,7 +53,7 @@ public function __construct(Builder $builder, $fieldName, $order = null)
     public function getExpression()
     {
         return [
-            '$sort' => $this->sort
+            '$sort' => $this->sort,
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/SortByCount.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/SortByCount.php
index a702010c70..2ee1c1890d 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/SortByCount.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/SortByCount.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
 use Doctrine\ODM\MongoDB\Aggregation\Stage;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use function substr;
 
 class SortByCount extends Stage
 {
@@ -15,7 +18,6 @@ class SortByCount extends Stage
     private $fieldName;
 
     /**
-     * @param Builder $builder
      * @param string $fieldName Expression to group by. To specify a field path,
      * prefix the field name with a dollar sign $ and enclose it in quotes.
      * The expression can not evaluate to an object.
@@ -34,7 +36,7 @@ public function __construct(Builder $builder, $fieldName, DocumentManager $docum
     public function getExpression()
     {
         return [
-            '$sortByCount' => $this->fieldName
+            '$sortByCount' => $this->fieldName,
         ];
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Unwind.php b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Unwind.php
index 91a35e95a7..4de31e6aef 100644
--- a/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Unwind.php
+++ b/lib/Doctrine/ODM/MongoDB/Aggregation/Stage/Unwind.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -8,8 +10,6 @@
 /**
  * Fluent interface for adding a $unwind stage to an aggregation pipeline.
  *
- * @author alcaeus <alcaeus@alcaeus.org>
- * @since 1.2
  */
 class Unwind extends Stage
 {
@@ -29,7 +29,6 @@ class Unwind extends Stage
     private $preserveNullAndEmptyArrays = false;
 
     /**
-     * @param Builder $builder
      * @param string $fieldName
      */
     public function __construct(Builder $builder, $fieldName)
@@ -47,23 +46,21 @@ public function getExpression()
         // Fallback behavior for MongoDB < 3.2
         if ($this->includeArrayIndex === null && ! $this->preserveNullAndEmptyArrays) {
             return [
-                '$unwind' => $this->fieldName
+                '$unwind' => $this->fieldName,
             ];
         }
 
         $unwind = ['path' => $this->fieldName];
 
         foreach (['includeArrayIndex', 'preserveNullAndEmptyArrays'] as $option) {
-            if ( ! $this->$option) {
+            if (! $this->$option) {
                 continue;
             }
 
             $unwind[$option] = $this->$option;
         }
 
-        return [
-            '$unwind' => $unwind
-        ];
+        return ['$unwind' => $unwind];
     }
 
     /**
@@ -73,7 +70,6 @@ public function getExpression()
      * @param string $includeArrayIndex
      * @return $this
      *
-     * @since 1.3
      */
     public function includeArrayIndex($includeArrayIndex)
     {
@@ -89,7 +85,6 @@ public function includeArrayIndex($includeArrayIndex)
      * @param bool $preserveNullAndEmptyArrays
      * @return $this
      *
-     * @since 1.3
      */
     public function preserveNullAndEmptyArrays($preserveNullAndEmptyArrays = true)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Configuration.php b/lib/Doctrine/ODM/MongoDB/Configuration.php
index a6d08087f5..aabedda3ca 100644
--- a/lib/Doctrine/ODM/MongoDB/Configuration.php
+++ b/lib/Doctrine/ODM/MongoDB/Configuration.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\Common\Annotations\AnnotationReader;
@@ -14,6 +16,7 @@
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionGenerator;
 use Doctrine\ODM\MongoDB\Repository\DefaultRepositoryFactory;
 use Doctrine\ODM\MongoDB\Repository\RepositoryFactory;
+use function trim;
 
 /**
  * Configuration class for the DocumentManager. When setting up your DocumentManager
@@ -25,7 +28,6 @@
  *     $config = new Configuration();
  *     $dm = DocumentManager::create(new Connection(), $config);
  *
- * @since       1.0
  */
 class Configuration
 {
@@ -43,7 +45,7 @@ class Configuration
      *
      * @var integer
      */
-    const AUTOGENERATE_NEVER = 0;
+    public const AUTOGENERATE_NEVER = 0;
 
     /**
      * Always generates a new proxy/hydrator/persistent collection in every request.
@@ -53,7 +55,7 @@ class Configuration
      *
      * @var integer
      */
-    const AUTOGENERATE_ALWAYS = 1;
+    public const AUTOGENERATE_ALWAYS = 1;
 
     /**
      * Autogenerate the proxy/hydrator/persistent collection class when the file does not exist.
@@ -63,7 +65,7 @@ class Configuration
      *
      * @var integer
      */
-    const AUTOGENERATE_FILE_NOT_EXISTS = 2;
+    public const AUTOGENERATE_FILE_NOT_EXISTS = 2;
 
     /**
      * Generate the proxy/hydrator/persistent collection classes using eval().
@@ -73,7 +75,7 @@ class Configuration
      *
      * @var integer
      */
-    const AUTOGENERATE_EVAL = 3;
+    public const AUTOGENERATE_EVAL = 3;
 
     /**
      * Adds a namespace under a certain alias.
@@ -95,7 +97,7 @@ public function addDocumentNamespace($alias, $namespace)
      */
     public function getDocumentNamespace($documentNamespaceAlias)
     {
-        if ( ! isset($this->attributes['documentNamespaces'][$documentNamespaceAlias])) {
+        if (! isset($this->attributes['documentNamespaces'][$documentNamespaceAlias])) {
             throw MongoDBException::unknownDocumentNamespace($documentNamespaceAlias);
         }
 
@@ -116,7 +118,6 @@ public function getDocumentNamespaces()
      * Set the document alias map
      *
      * @param array $documentNamespaces
-     * @return void
      */
     public function setDocumentNamespaces(array $documentNamespaces)
     {
@@ -126,7 +127,6 @@ public function setDocumentNamespaces(array $documentNamespaces)
     /**
      * Sets the cache driver implementation that is used for metadata caching.
      *
-     * @param MappingDriver $driverImpl
      * @todo Force parameter to be a Closure to ensure lazy evaluation
      *       (as soon as a metadata cache is in effect, the driver never needs to initialize).
      */
@@ -141,11 +141,11 @@ public function setMetadataDriverImpl(MappingDriver $driverImpl)
      * @param array $paths
      * @return Mapping\Driver\AnnotationDriver
      */
-    public function newDefaultAnnotationDriver($paths = array())
+    public function newDefaultAnnotationDriver($paths = [])
     {
         $reader = new AnnotationReader();
 
-        return new AnnotationDriver($reader, (array)$paths);
+        return new AnnotationDriver($reader, (array) $paths);
     }
 
     /**
@@ -161,7 +161,7 @@ public function getMetadataDriverImpl()
     /**
      * Gets the cache driver implementation that is used for metadata caching.
      *
-     * @return \Doctrine\Common\Cache\Cache
+     * @return Cache
      */
     public function getMetadataCacheImpl()
     {
@@ -171,7 +171,6 @@ public function getMetadataCacheImpl()
     /**
      * Sets the cache driver implementation that is used for metadata caching.
      *
-     * @param \Doctrine\Common\Cache\Cache $cacheImpl
      */
     public function setMetadataCacheImpl(Cache $cacheImpl)
     {
@@ -202,7 +201,7 @@ public function getProxyDir()
      * Gets a boolean flag that indicates whether proxy classes should always be regenerated
      * during each script execution.
      *
-     * @return boolean|integer
+     * @return bool|int
      */
     public function getAutoGenerateProxyClasses()
     {
@@ -213,7 +212,7 @@ public function getAutoGenerateProxyClasses()
      * Sets a boolean flag that indicates whether proxy classes should always be regenerated
      * during each script execution.
      *
-     * @param boolean|int $bool Possible values are constants of Doctrine\Common\Proxy\AbstractProxyFactory
+     * @param bool|int $bool Possible values are constants of Doctrine\Common\Proxy\AbstractProxyFactory
      */
     public function setAutoGenerateProxyClasses($bool)
     {
@@ -264,7 +263,7 @@ public function getHydratorDir()
      * Gets a boolean flag that indicates whether hydrator classes should always be regenerated
      * during each script execution.
      *
-     * @return boolean|integer Possible values are defined constants
+     * @return bool|int Possible values are defined constants
      */
     public function getAutoGenerateHydratorClasses()
     {
@@ -275,7 +274,7 @@ public function getAutoGenerateHydratorClasses()
      * Sets a boolean flag that indicates whether hydrator classes should always be regenerated
      * during each script execution.
      *
-     * @param boolean|integer $bool
+     * @param bool|int $bool
      */
     public function setAutoGenerateHydratorClasses($bool)
     {
@@ -326,7 +325,7 @@ public function getPersistentCollectionDir()
      * Gets a integer flag that indicates how and when persistent collection
      * classes should be generated.
      *
-     * @return integer Possible values are defined constants
+     * @return int Possible values are defined constants
      */
     public function getAutoGeneratePersistentCollectionClasses()
     {
@@ -337,7 +336,7 @@ public function getAutoGeneratePersistentCollectionClasses()
      * Sets a integer flag that indicates how and when persistent collection
      * classes should be generated.
      *
-     * @param integer $mode Possible values are defined constants
+     * @param int $mode Possible values are defined constants
      */
     public function setAutoGeneratePersistentCollectionClasses($mode)
     {
@@ -402,7 +401,7 @@ public function setClassMetadataFactoryName($cmfName)
      */
     public function getClassMetadataFactoryName()
     {
-        if ( ! isset($this->attributes['classMetadataFactoryName'])) {
+        if (! isset($this->attributes['classMetadataFactoryName'])) {
             $this->attributes['classMetadataFactoryName'] = ClassMetadataFactory::class;
         }
         return $this->attributes['classMetadataFactoryName'];
@@ -415,7 +414,7 @@ public function getClassMetadataFactoryName()
      */
     public function getDefaultCommitOptions()
     {
-        return $this->attributes['defaultCommitOptions'] ?? array('w' => 1);
+        return $this->attributes['defaultCommitOptions'] ?? ['w' => 1];
     }
 
     /**
@@ -435,12 +434,12 @@ public function setDefaultCommitOptions($defaultCommitOptions)
      * @param string $className  The class name of the filter.
      * @param array  $parameters The parameters for the filter.
      */
-    public function addFilter($name, $className, array $parameters = array())
+    public function addFilter($name, $className, array $parameters = [])
     {
-        $this->attributes['filters'][$name] = array(
+        $this->attributes['filters'][$name] = [
             'class' => $className,
-            'parameters' => $parameters
-        );
+            'parameters' => $parameters,
+        ];
     }
 
     /**
@@ -476,7 +475,6 @@ public function getFilterParameters($name)
      *
      * @param string $className
      *
-     * @return void
      *
      * @throws MongoDBException If not is a ObjectRepository
      */
@@ -484,7 +482,7 @@ public function setDefaultRepositoryClassName($className)
     {
         $reflectionClass = new \ReflectionClass($className);
 
-        if ( ! $reflectionClass->implementsInterface(ObjectRepository::class)) {
+        if (! $reflectionClass->implementsInterface(ObjectRepository::class)) {
             throw MongoDBException::invalidDocumentRepository($className);
         }
 
@@ -504,7 +502,6 @@ public function getDefaultRepositoryClassName()
     /**
      * Set the document repository factory.
      *
-     * @param RepositoryFactory $repositoryFactory
      */
     public function setRepositoryFactory(RepositoryFactory $repositoryFactory)
     {
@@ -524,7 +521,6 @@ public function getRepositoryFactory()
     /**
      * Set the persistent collection factory.
      *
-     * @param PersistentCollectionFactory $persistentCollectionFactory
      */
     public function setPersistentCollectionFactory(PersistentCollectionFactory $persistentCollectionFactory)
     {
@@ -538,7 +534,7 @@ public function setPersistentCollectionFactory(PersistentCollectionFactory $pers
      */
     public function getPersistentCollectionFactory()
     {
-        if ( ! isset($this->attributes['persistentCollectionFactory'])) {
+        if (! isset($this->attributes['persistentCollectionFactory'])) {
             $this->attributes['persistentCollectionFactory'] = new DefaultPersistentCollectionFactory();
         }
         return $this->attributes['persistentCollectionFactory'];
@@ -547,7 +543,6 @@ public function getPersistentCollectionFactory()
     /**
      * Set the persistent collection generator.
      *
-     * @param PersistentCollectionGenerator $persistentCollectionGenerator
      */
     public function setPersistentCollectionGenerator(PersistentCollectionGenerator $persistentCollectionGenerator)
     {
@@ -561,7 +556,7 @@ public function setPersistentCollectionGenerator(PersistentCollectionGenerator $
      */
     public function getPersistentCollectionGenerator()
     {
-        if ( ! isset($this->attributes['persistentCollectionGenerator'])) {
+        if (! isset($this->attributes['persistentCollectionGenerator'])) {
             $this->attributes['persistentCollectionGenerator'] = new DefaultPersistentCollectionGenerator(
                 $this->getPersistentCollectionDir(),
                 $this->getPersistentCollectionNamespace()
diff --git a/lib/Doctrine/ODM/MongoDB/DocumentManager.php b/lib/Doctrine/ODM/MongoDB/DocumentManager.php
index 58e2f6df34..aeb19137ba 100644
--- a/lib/Doctrine/ODM/MongoDB/DocumentManager.php
+++ b/lib/Doctrine/ODM/MongoDB/DocumentManager.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\Common\EventManager;
 use Doctrine\Common\Persistence\ObjectManager;
 use Doctrine\Common\Persistence\ObjectRepository;
+use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
-use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\Proxy\ProxyFactory;
 use Doctrine\ODM\MongoDB\Query\FilterCollection;
 use Doctrine\ODM\MongoDB\Repository\RepositoryFactory;
@@ -15,6 +18,12 @@
 use MongoDB\Collection;
 use MongoDB\Database;
 use MongoDB\Driver\ReadPreference;
+use function array_search;
+use function get_class;
+use function gettype;
+use function is_object;
+use function ltrim;
+use function sprintf;
 
 /**
  * The DocumentManager class is the central access point for managing the
@@ -25,7 +34,6 @@
  *     $config = new Configuration();
  *     $dm = DocumentManager::create(new Connection(), $config);
  *
- * @since       1.0
  */
 class DocumentManager implements ObjectManager
 {
@@ -39,14 +47,14 @@ class DocumentManager implements ObjectManager
     /**
      * The used Configuration.
      *
-     * @var \Doctrine\ODM\MongoDB\Configuration
+     * @var Configuration
      */
     private $config;
 
     /**
      * The metadata factory, used to retrieve the ODM metadata of document classes.
      *
-     * @var \Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory
+     * @var ClassMetadataFactory
      */
     private $metadataFactory;
 
@@ -60,7 +68,7 @@ class DocumentManager implements ObjectManager
     /**
      * The event manager that is the central point of the event system.
      *
-     * @var \Doctrine\Common\EventManager
+     * @var EventManager
      */
     private $eventManager;
 
@@ -97,14 +105,14 @@ class DocumentManager implements ObjectManager
      *
      * @var Database[]
      */
-    private $documentDatabases = array();
+    private $documentDatabases = [];
 
     /**
      * Array of cached document collection instances that are lazily loaded.
      *
      * @var Collection[]
      */
-    private $documentCollections = array();
+    private $documentCollections = [];
 
     /**
      * Whether the DocumentManager is closed or not.
@@ -116,7 +124,7 @@ class DocumentManager implements ObjectManager
     /**
      * Collection of query filters.
      *
-     * @var \Doctrine\ODM\MongoDB\Query\FilterCollection
+     * @var FilterCollection
      */
     private $filterCollection;
 
@@ -124,11 +132,8 @@ class DocumentManager implements ObjectManager
      * Creates a new Document that operates on the given Mongo connection
      * and uses the given Configuration.
      *
-     * @param Client|null $client
-     * @param Configuration|null $config
-     * @param \Doctrine\Common\EventManager|null $eventManager
      */
-    protected function __construct(Client $client = null, Configuration $config = null, EventManager $eventManager = null)
+    protected function __construct(?Client $client = null, ?Configuration $config = null, ?EventManager $eventManager = null)
     {
         $this->config = $config ?: new Configuration();
         $this->eventManager = $eventManager ?: new EventManager();
@@ -155,7 +160,8 @@ protected function __construct(Client $client = null, Configuration $config = nu
         $this->unitOfWork = new UnitOfWork($this, $this->eventManager, $this->hydratorFactory);
         $this->hydratorFactory->setUnitOfWork($this->unitOfWork);
         $this->schemaManager = new SchemaManager($this, $this->metadataFactory);
-        $this->proxyFactory = new ProxyFactory($this,
+        $this->proxyFactory = new ProxyFactory(
+            $this,
             $this->config->getProxyDir(),
             $this->config->getProxyNamespace(),
             $this->config->getAutoGenerateProxyClasses()
@@ -178,12 +184,9 @@ public function getProxyFactory()
      * and uses the given Configuration.
      *
      * @static
-     * @param Client|null $client
-     * @param Configuration|null $config
-     * @param \Doctrine\Common\EventManager|null $eventManager
      * @return DocumentManager
      */
-    public static function create(Client $client = null, Configuration $config = null, EventManager $eventManager = null)
+    public static function create(?Client $client = null, ?Configuration $config = null, ?EventManager $eventManager = null)
     {
         return new static($client, $config, $eventManager);
     }
@@ -191,7 +194,7 @@ public static function create(Client $client = null, Configuration $config = nul
     /**
      * Gets the EventManager used by the DocumentManager.
      *
-     * @return \Doctrine\Common\EventManager
+     * @return EventManager
      */
     public function getEventManager()
     {
@@ -211,7 +214,7 @@ public function getClient()
     /**
      * Gets the metadata factory used to gather the metadata of classes.
      *
-     * @return \Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory
+     * @return ClassMetadataFactory
      */
     public function getMetadataFactory()
     {
@@ -254,7 +257,7 @@ public function getHydratorFactory()
     /**
      * Returns SchemaManager, used to create/drop indexes/collections/databases.
      *
-     * @return \Doctrine\ODM\MongoDB\SchemaManager
+     * @return SchemaManager
      */
     public function getSchemaManager()
     {
@@ -265,7 +268,7 @@ public function getSchemaManager()
      * Returns the metadata for a class.
      *
      * @param string $className The class name.
-     * @return \Doctrine\ODM\MongoDB\Mapping\ClassMetadata
+     * @return ClassMetadata
      * @internal Performance-sensitive method.
      */
     public function getClassMetadata($className)
@@ -320,11 +323,11 @@ public function getDocumentCollection($className)
         $metadata = $this->metadataFactory->getMetadataFor($className);
         $collectionName = $metadata->getCollection();
 
-        if ( ! $collectionName) {
+        if (! $collectionName) {
             throw MongoDBException::documentNotMappedToCollection($className);
         }
 
-        if ( ! isset($this->documentCollections[$className])) {
+        if (! isset($this->documentCollections[$className])) {
             $db = $this->getDocumentDatabase($className);
 
             $options = [];
@@ -384,7 +387,7 @@ public function createAggregationBuilder($documentName)
      */
     public function persist($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->errorIfClosed();
@@ -402,7 +405,7 @@ public function persist($document)
      */
     public function remove($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->errorIfClosed();
@@ -418,7 +421,7 @@ public function remove($document)
      */
     public function refresh($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->errorIfClosed();
@@ -437,7 +440,7 @@ public function refresh($document)
      */
     public function detach($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->unitOfWork->detach($document);
@@ -455,7 +458,7 @@ public function detach($document)
      */
     public function merge($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->errorIfClosed();
@@ -466,13 +469,13 @@ public function merge($document)
      * Acquire a lock on the given document.
      *
      * @param object $document
-     * @param int $lockMode
-     * @param int $lockVersion
+     * @param int    $lockMode
+     * @param int    $lockVersion
      * @throws \InvalidArgumentException
      */
     public function lock($document, $lockMode, $lockVersion = null)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->unitOfWork->lock($document, $lockMode, $lockVersion);
@@ -486,7 +489,7 @@ public function lock($document, $lockMode, $lockVersion = null)
      */
     public function unlock($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         $this->unitOfWork->unlock($document);
@@ -495,7 +498,7 @@ public function unlock($document)
     /**
      * Gets the repository for a document class.
      *
-     * @param string $documentName  The name of the Document.
+     * @param string $documentName The name of the Document.
      * @return ObjectRepository  The repository.
      */
     public function getRepository($documentName)
@@ -511,7 +514,7 @@ public function getRepository($documentName)
      * @param array $options Array of options to be used with batchInsert(), update() and remove()
      * @throws \InvalidArgumentException
      */
-    public function flush(array $options = array())
+    public function flush(array $options = [])
     {
         $this->errorIfClosed();
         $this->unitOfWork->commit($options);
@@ -525,7 +528,7 @@ public function flush(array $options = array())
      * has its identifier populated. Otherwise a proxy is returned that automatically
      * loads itself on first access.
      *
-     * @param string $documentName
+     * @param string        $documentName
      * @param string|object $identifier
      * @return mixed|object The document reference.
      */
@@ -539,8 +542,8 @@ public function getReference($documentName, $identifier)
             return $document;
         }
 
-        $document = $this->proxyFactory->getProxy($class->name, array($class->identifier => $identifier));
-        $this->unitOfWork->registerManaged($document, $identifier, array());
+        $document = $this->proxyFactory->getProxy($class->name, [$class->identifier => $identifier]);
+        $this->unitOfWork->registerManaged($document, $identifier, []);
 
         return $document;
     }
@@ -561,7 +564,7 @@ public function getReference($documentName, $identifier)
      * never be loaded in the first place.
      *
      * @param string $documentName The name of the document type.
-     * @param mixed $identifier The document identifier.
+     * @param mixed  $identifier   The document identifier.
      * @return object The (partial) document reference.
      */
     public function getPartialReference($documentName, $identifier)
@@ -574,7 +577,7 @@ public function getPartialReference($documentName, $identifier)
         }
         $document = $class->newInstance();
         $class->setIdentifierValue($document, $identifier);
-        $this->unitOfWork->registerManaged($document, $identifier, array());
+        $this->unitOfWork->registerManaged($document, $identifier, []);
 
         return $document;
     }
@@ -585,9 +588,9 @@ public function getPartialReference($documentName, $identifier)
      * This is just a convenient shortcut for getRepository($documentName)->find($id).
      *
      * @param string $documentName
-     * @param mixed $identifier
-     * @param int $lockMode
-     * @param int $lockVersion
+     * @param mixed  $identifier
+     * @param int    $lockMode
+     * @param int    $lockVersion
      * @return object $document
      */
     public function find($documentName, $identifier, $lockMode = LockMode::NONE, $lockVersion = null)
@@ -624,11 +627,11 @@ public function close()
      *
      * @param object $document
      * @throws \InvalidArgumentException When the $document param is not an object
-     * @return boolean TRUE if this DocumentManager currently manages the given document, FALSE otherwise.
+     * @return bool TRUE if this DocumentManager currently manages the given document, FALSE otherwise.
      */
     public function contains($document)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException(gettype($document));
         }
         return $this->unitOfWork->isScheduledForInsert($document) ||
@@ -649,8 +652,8 @@ public function getConfiguration()
     /**
      * Returns a reference to the supplied document.
      *
-     * @param object $document A document object
-     * @param array $referenceMapping Mapping for the field that references the document
+     * @param object $document         A document object
+     * @param array  $referenceMapping Mapping for the field that references the document
      *
      * @throws \InvalidArgumentException
      * @throws MappingException
@@ -658,7 +661,7 @@ public function getConfiguration()
      */
     public function createReference($document, array $referenceMapping)
     {
-        if ( ! is_object($document)) {
+        if (! is_object($document)) {
             throw new \InvalidArgumentException('Cannot create a DBRef, the document is not an object');
         }
 
@@ -682,7 +685,6 @@ public function createReference($document, array $referenceMapping)
                 return $class->getDatabaseIdentifierValue($id);
                 break;
 
-
             case ClassMetadata::REFERENCE_STORE_AS_REF:
                 $reference = ['id' => $class->getDatabaseIdentifierValue($id)];
                 break;
@@ -758,17 +760,17 @@ private function errorIfClosed()
      */
     public function isOpen()
     {
-        return ( ! $this->closed);
+        return ! $this->closed;
     }
 
     /**
      * Gets the filter collection.
      *
-     * @return \Doctrine\ODM\MongoDB\Query\FilterCollection The active filter collection.
+     * @return FilterCollection The active filter collection.
      */
     public function getFilterCollection()
     {
-        if (null === $this->filterCollection) {
+        if ($this->filterCollection === null) {
             $this->filterCollection = new FilterCollection($this);
         }
 
diff --git a/lib/Doctrine/ODM/MongoDB/DocumentNotFoundException.php b/lib/Doctrine/ODM/MongoDB/DocumentNotFoundException.php
index a0fc887868..92cd81bd9e 100644
--- a/lib/Doctrine/ODM/MongoDB/DocumentNotFoundException.php
+++ b/lib/Doctrine/ODM/MongoDB/DocumentNotFoundException.php
@@ -1,12 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
+use function json_encode;
+use function sprintf;
+
 /**
  * Class for exception when encountering proxy object that has
  * an identifier that does not exist in the database.
  *
- * @since       1.0
  */
 class DocumentNotFoundException extends MongoDBException
 {
@@ -14,7 +18,7 @@ public static function documentNotFound($className, $identifier)
     {
         return new self(sprintf(
             'The "%s" document with identifier %s could not be found.',
-            $className, 
+            $className,
             json_encode($identifier)
         ));
     }
diff --git a/lib/Doctrine/ODM/MongoDB/DocumentRepository.php b/lib/Doctrine/ODM/MongoDB/DocumentRepository.php
index ee6bba6dac..d41825be08 100644
--- a/lib/Doctrine/ODM/MongoDB/DocumentRepository.php
+++ b/lib/Doctrine/ODM/MongoDB/DocumentRepository.php
@@ -1,15 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\Collections\Criteria;
 use Doctrine\Common\Collections\Selectable;
-use Doctrine\Common\Inflector\Inflector;
 use Doctrine\Common\Persistence\ObjectRepository;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Query\QueryExpressionVisitor;
+use function is_array;
 
 /**
  * A DocumentRepository serves as a repository for documents with generic as well as
@@ -18,7 +20,6 @@
  * This class is designed for inheritance and users can subclass this class to
  * write their own repositories with business-specific methods to locate documents.
  *
- * @since       1.0
  */
 class DocumentRepository implements ObjectRepository, Selectable
 {
@@ -46,9 +47,9 @@ class DocumentRepository implements ObjectRepository, Selectable
      * Initializes this instance with the specified document manager, unit of work and
      * class metadata.
      *
-     * @param DocumentManager $dm The DocumentManager to use.
-     * @param UnitOfWork $uow The UnitOfWork to use.
-     * @param ClassMetadata $classMetadata The class metadata.
+     * @param DocumentManager $dm            The DocumentManager to use.
+     * @param UnitOfWork      $uow           The UnitOfWork to use.
+     * @param ClassMetadata   $classMetadata The class metadata.
      */
     public function __construct(DocumentManager $dm, UnitOfWork $uow, ClassMetadata $classMetadata)
     {
@@ -90,9 +91,9 @@ public function clear()
      * Finds a document matching the specified identifier. Optionally a lock mode and
      * expected version may be specified.
      *
-     * @param mixed $id Identifier.
-     * @param int $lockMode Optional. Lock mode; one of the LockMode constants.
-     * @param int $lockVersion Optional. Expected version.
+     * @param mixed $id          Identifier.
+     * @param int   $lockMode    Optional. Lock mode; one of the LockMode constants.
+     * @param int   $lockVersion Optional. Expected version.
      * @throws Mapping\MappingException
      * @throws LockException
      * @return object|null The document, if found, otherwise null.
@@ -123,14 +124,14 @@ public function find($id, $lockMode = LockMode::NONE, $lockVersion = null)
             return $document; // Hit!
         }
 
-        $criteria = array('_id' => $id);
+        $criteria = ['_id' => $id];
 
         if ($lockMode === LockMode::NONE) {
             return $this->getDocumentPersister()->load($criteria);
         }
 
         if ($lockMode === LockMode::OPTIMISTIC) {
-            if (!$this->class->isVersioned) {
+            if (! $this->class->isVersioned) {
                 throw LockException::notVersioned($this->documentName);
             }
             if ($document = $this->getDocumentPersister()->load($criteria)) {
@@ -140,7 +141,7 @@ public function find($id, $lockMode = LockMode::NONE, $lockVersion = null)
             return $document;
         }
 
-        return $this->getDocumentPersister()->load($criteria, null, array(), $lockMode);
+        return $this->getDocumentPersister()->load($criteria, null, [], $lockMode);
     }
 
     /**
@@ -150,20 +151,20 @@ public function find($id, $lockMode = LockMode::NONE, $lockVersion = null)
      */
     public function findAll()
     {
-        return $this->findBy(array());
+        return $this->findBy([]);
     }
 
     /**
      * Finds documents by a set of criteria.
      *
-     * @param array        $criteria Query criteria
-     * @param array        $sort     Sort array for Cursor::sort()
-     * @param integer|null $limit    Limit for Cursor::limit()
-     * @param integer|null $skip     Skip for Cursor::skip()
+     * @param array    $criteria Query criteria
+     * @param array    $sort     Sort array for Cursor::sort()
+     * @param int|null $limit    Limit for Cursor::limit()
+     * @param int|null $skip     Skip for Cursor::skip()
      *
      * @return array
      */
-    public function findBy(array $criteria, array $sort = null, $limit = null, $skip = null)
+    public function findBy(array $criteria, ?array $sort = null, $limit = null, $skip = null)
     {
         return $this->getDocumentPersister()->loadAll($criteria, $sort, $limit, $skip)->toArray(false);
     }
@@ -216,7 +217,6 @@ public function getClassName()
      * returns a new collection containing these elements.
      *
      * @see Selectable::matching()
-     * @param Criteria $criteria
      * @return Collection
      */
     public function matching(Criteria $criteria)
diff --git a/lib/Doctrine/ODM/MongoDB/Event/DocumentNotFoundEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/DocumentNotFoundEventArgs.php
index db12ccecd6..5a9c7a4e25 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/DocumentNotFoundEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/DocumentNotFoundEventArgs.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 /*
  *  $Id$
  *
@@ -26,7 +29,6 @@
 /**
  * Provides event arguments for the documentNotFound event.
  *
- * @since 1.1
  */
 class DocumentNotFoundEventArgs extends LifecycleEventArgs
 {
@@ -41,10 +43,9 @@ class DocumentNotFoundEventArgs extends LifecycleEventArgs
     private $disableException = false;
 
     /**
-     * Constructor.
+     *
      *
      * @param object $document
-     * @param DocumentManager $dm
      * @param string $identifier
      */
     public function __construct($document, DocumentManager $dm, $identifier)
diff --git a/lib/Doctrine/ODM/MongoDB/Event/LifecycleEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/LifecycleEventArgs.php
index 22834910ee..61b07f657f 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/LifecycleEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/LifecycleEventArgs.php
@@ -1,14 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\Common\Persistence\Event\LifecycleEventArgs as BaseLifecycleEventArgs;
+use Doctrine\ODM\MongoDB\DocumentManager;
 
 /**
  * Lifecycle Events are triggered by the UnitOfWork during lifecycle transitions
  * of documents.
  *
- * @since 1.0
  */
 class LifecycleEventArgs extends BaseLifecycleEventArgs
 {
@@ -25,7 +27,7 @@ public function getDocument()
     /**
      * Retrieves the associated DocumentManager.
      *
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     public function getDocumentManager()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/LoadClassMetadataEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/LoadClassMetadataEventArgs.php
index 9f81b2fe60..de7d4b229f 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/LoadClassMetadataEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/LoadClassMetadataEventArgs.php
@@ -1,20 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\Common\Persistence\Event\LoadClassMetadataEventArgs as BaseLoadClassMetadataEventArgs;
+use Doctrine\ODM\MongoDB\DocumentManager;
 
 /**
  * Class that holds event arguments for a loadMetadata event.
  *
- * @since 1.0
  */
 class LoadClassMetadataEventArgs extends BaseLoadClassMetadataEventArgs
 {
     /**
      * Retrieves the associated DocumentManager.
      *
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     public function getDocumentManager()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/ManagerEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/ManagerEventArgs.php
index b53cd25b1c..e71baa2d44 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/ManagerEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/ManagerEventArgs.php
@@ -1,20 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\Common\Persistence\Event\ManagerEventArgs as BaseManagerEventArgs;
+use Doctrine\ODM\MongoDB\DocumentManager;
 
 /**
  * Provides event arguments for the flush events.
  *
- * @since 1.0
  */
 class ManagerEventArgs extends BaseManagerEventArgs
 {
     /**
      * Retrieves the associated DocumentManager.
      *
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     public function getDocumentManager()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/OnClearEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/OnClearEventArgs.php
index dff48abcbf..5503dd72d4 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/OnClearEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/OnClearEventArgs.php
@@ -1,20 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\Common\Persistence\Event\OnClearEventArgs as BaseOnClearEventArgs;
+use Doctrine\ODM\MongoDB\DocumentManager;
 
 /**
  * Provides event arguments for the onClear event.
  *
- * @since 1.0
  */
 class OnClearEventArgs extends BaseOnClearEventArgs
 {
     /**
      * Retrieves the associated DocumentManager.
      *
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     public function getDocumentManager()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/OnFlushEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/OnFlushEventArgs.php
index 656feccd5f..d836947caf 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/OnFlushEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/OnFlushEventArgs.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 /**
  * Provides event arguments for the onFlush event.
  *
- * @since 1.0
  */
 class OnFlushEventArgs extends ManagerEventArgs
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/PostCollectionLoadEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/PostCollectionLoadEventArgs.php
index 0d24d5e759..44708c44d0 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/PostCollectionLoadEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/PostCollectionLoadEventArgs.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -8,7 +10,6 @@
 /**
  * Class that holds arguments for postCollectionLoad event.
  *
- * @since 1.1
  */
 class PostCollectionLoadEventArgs extends ManagerEventArgs
 {
@@ -17,10 +18,6 @@ class PostCollectionLoadEventArgs extends ManagerEventArgs
      */
     private $collection;
 
-    /**
-     * @param PersistentCollectionInterface $collection
-     * @param DocumentManager $dm
-     */
     public function __construct(PersistentCollectionInterface $collection, DocumentManager $dm)
     {
         parent::__construct($dm);
diff --git a/lib/Doctrine/ODM/MongoDB/Event/PostFlushEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/PostFlushEventArgs.php
index 7819beeae7..7663096cbc 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/PostFlushEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/PostFlushEventArgs.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 /**
  * Provides event arguments for the postFlush event.
  *
- * @since 1.0
  */
 class PostFlushEventArgs extends ManagerEventArgs
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/PreFlushEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/PreFlushEventArgs.php
index 5c8643c6a2..05cc0bd560 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/PreFlushEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/PreFlushEventArgs.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 /**
  * Provides event arguments for the preFlush event.
  *
- * @since 1.0
  */
 class PreFlushEventArgs extends ManagerEventArgs
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/PreLoadEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/PreLoadEventArgs.php
index ac664f113f..033a46738a 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/PreLoadEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/PreLoadEventArgs.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -7,7 +9,6 @@
 /**
  * Class that holds event arguments for a preLoad event.
  *
- * @since 1.0
  */
 class PreLoadEventArgs extends LifecycleEventArgs
 {
@@ -17,11 +18,10 @@ class PreLoadEventArgs extends LifecycleEventArgs
     private $data;
 
     /**
-     * Constructor.
      *
-     * @param object          $document
-     * @param DocumentManager $dm
-     * @param array           $data     Array of data to be loaded and hydrated
+     *
+     * @param object $document
+     * @param array  $data     Array of data to be loaded and hydrated
      */
     public function __construct($document, DocumentManager $dm, array &$data)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Event/PreUpdateEventArgs.php b/lib/Doctrine/ODM/MongoDB/Event/PreUpdateEventArgs.php
index a8f506af3c..47a262a4fa 100644
--- a/lib/Doctrine/ODM/MongoDB/Event/PreUpdateEventArgs.php
+++ b/lib/Doctrine/ODM/MongoDB/Event/PreUpdateEventArgs.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Event;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
+use function get_class;
+use function sprintf;
 
 /**
  * Class that holds event arguments for a preUpdate event.
  *
- * @since 1.0
  */
 class PreUpdateEventArgs extends LifecycleEventArgs
 {
@@ -17,11 +20,10 @@ class PreUpdateEventArgs extends LifecycleEventArgs
     private $documentChangeSet;
 
     /**
-     * Constructor.
      *
-     * @param object          $document
-     * @param DocumentManager $dm
-     * @param array           $changeSet
+     *
+     * @param object $document
+     * @param array  $changeSet
      */
     public function __construct($document, DocumentManager $dm, array $changeSet)
     {
@@ -44,7 +46,7 @@ public function getDocumentChangeSet()
      *
      * @param string $field
      *
-     * @return boolean
+     * @return bool
      */
     public function hasChangedField($field)
     {
@@ -99,7 +101,7 @@ public function setNewValue($field, $value)
      */
     private function assertValidField($field)
     {
-        if ( ! isset($this->documentChangeSet[$field])) {
+        if (! isset($this->documentChangeSet[$field])) {
             throw new \InvalidArgumentException(sprintf(
                 'Field "%s" is not a valid field of the document "%s" in PreUpdateEventArgs.',
                 $field,
diff --git a/lib/Doctrine/ODM/MongoDB/Events.php b/lib/Doctrine/ODM/MongoDB/Events.php
index 4351734692..12bd41dd14 100644
--- a/lib/Doctrine/ODM/MongoDB/Events.php
+++ b/lib/Doctrine/ODM/MongoDB/Events.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 /**
@@ -7,72 +9,73 @@
  *
  * This class cannot be instantiated.
  *
- * @since       1.0
  */
 final class Events
 {
-    private function __construct() {}
+    private function __construct()
+    {
+    }
 
     /**
      * The preRemove event occurs for a given document before the respective
      * DocumentManager remove operation for that document is executed.
-     * 
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const preRemove = 'preRemove';
+    public const preRemove = 'preRemove';
 
     /**
-     * The postRemove event occurs for a document after the document has 
+     * The postRemove event occurs for a document after the document has
      * been deleted. It will be invoked after the database delete operations.
-     * 
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const postRemove = 'postRemove';
+    public const postRemove = 'postRemove';
 
     /**
      * The prePersist event occurs for a given document before the respective
      * DocumentManager persist operation for that document is executed.
-     * 
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const prePersist = 'prePersist';
+    public const prePersist = 'prePersist';
 
     /**
-     * The postPersist event occurs for a document after the document has 
+     * The postPersist event occurs for a document after the document has
      * been made persistent. It will be invoked after the database insert operations.
      * Generated primary key values are available in the postPersist event.
-     * 
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const postPersist = 'postPersist';
+    public const postPersist = 'postPersist';
 
     /**
-     * The preUpdate event occurs before the database update operations to 
-     * document data. 
-     * 
+     * The preUpdate event occurs before the database update operations to
+     * document data.
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const preUpdate = 'preUpdate';
+    public const preUpdate = 'preUpdate';
 
     /**
-     * The postUpdate event occurs after the database update operations to 
-     * document data. 
-     * 
+     * The postUpdate event occurs after the database update operations to
+     * document data.
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const postUpdate = 'postUpdate';
+    public const postUpdate = 'postUpdate';
 
     /**
      * The preLoad event occurs for a document before the document has been loaded
@@ -83,37 +86,37 @@ private function __construct() {}
      *
      * @var string
      */
-    const preLoad = 'preLoad';
+    public const preLoad = 'preLoad';
 
     /**
      * The postLoad event occurs for a document after the document has been loaded
      * into the current DocumentManager from the database or after the refresh operation
      * has been applied to it.
-     * 
+     *
      * Note that the postLoad event occurs for a document before any associations have been
      * initialized. Therefore it is not safe to access associations in a postLoad callback
      * or event handler.
-     * 
+     *
      * This is a document lifecycle event.
-     * 
+     *
      * @var string
      */
-    const postLoad = 'postLoad';
+    public const postLoad = 'postLoad';
 
     /**
      * The loadClassMetadata event occurs after the mapping metadata for a class
      * has been loaded from a mapping source (annotations/xml).
-     * 
+     *
      * @var string
      */
-    const loadClassMetadata = 'loadClassMetadata';
+    public const loadClassMetadata = 'loadClassMetadata';
 
     /**
      * The preFlush event occurs when the DocumentManager#flush() operation is invoked,
      * but before any changes to managed documents have been calculated. This event is
      * always raised right after DocumentManager#flush() call.
      */
-    const preFlush = 'preFlush';
+    public const preFlush = 'preFlush';
 
     /**
      * The onFlush event occurs when the DocumentManager#flush() operation is invoked,
@@ -121,10 +124,10 @@ private function __construct() {}
      * actual database operations are executed. The event is only raised if there is
      * actually something to do for the underlying UnitOfWork. If nothing needs to be done,
      * the onFlush event is not raised.
-     * 
+     *
      * @var string
      */
-    const onFlush = 'onFlush';
+    public const onFlush = 'onFlush';
 
     /**
      * The postFlush event occurs when the DocumentManager#flush() operation is invoked and
@@ -135,7 +138,7 @@ private function __construct() {}
      *
      * @var string
      */
-    const postFlush = 'postFlush';
+    public const postFlush = 'postFlush';
 
     /**
      * The onClear event occurs when the DocumentManager#clear() operation is invoked,
@@ -143,7 +146,7 @@ private function __construct() {}
      *
      * @var string
      */
-    const onClear = 'onClear';
+    public const onClear = 'onClear';
 
     /**
      * The documentNotFound event occurs if a proxy object could not be found in
@@ -151,12 +154,12 @@ private function __construct() {}
      *
      * @var string
      */
-    const documentNotFound = 'documentNotFound';
+    public const documentNotFound = 'documentNotFound';
 
     /**
      * The postCollectionLoad event occurs after collection is initialized (loaded).
      *
      * @var string
      */
-    const postCollectionLoad = 'postCollectionLoad';
+    public const postCollectionLoad = 'postCollectionLoad';
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorException.php b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorException.php
index cff03f3097..974e9e4d64 100644
--- a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorException.php
+++ b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Hydrator;
 
 use Doctrine\ODM\MongoDB\MongoDBException;
@@ -7,7 +9,6 @@
 /**
  * MongoDB ODM Hydrator Exception
  *
- * @since  1.0
  */
 class HydratorException extends MongoDBException
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php
index f769a879dc..f518be6591 100644
--- a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php
@@ -1,8 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Hydrator;
 
 use Doctrine\Common\EventManager;
+use Doctrine\ODM\MongoDB\Configuration;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Event\LifecycleEventArgs;
 use Doctrine\ODM\MongoDB\Event\PreLoadEventArgs;
@@ -11,41 +14,56 @@
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\Types\Type;
 use Doctrine\ODM\MongoDB\UnitOfWork;
-use Doctrine\ODM\MongoDB\Configuration;
+use const DIRECTORY_SEPARATOR;
+use function array_key_exists;
+use function chmod;
+use function class_exists;
+use function dirname;
+use function file_exists;
+use function file_put_contents;
+use function get_class;
+use function is_dir;
+use function is_writable;
+use function mkdir;
+use function rename;
+use function rtrim;
+use function sprintf;
+use function str_replace;
+use function substr;
+use function uniqid;
 
 /**
  * The HydratorFactory class is responsible for instantiating a correct hydrator
  * type based on document's ClassMetadata
  *
- * @since       1.0
  */
 class HydratorFactory
 {
     /**
      * The DocumentManager this factory is bound to.
      *
-     * @var \Doctrine\ODM\MongoDB\DocumentManager
+     * @var DocumentManager
      */
     private $dm;
 
     /**
      * The UnitOfWork used to coordinate object-level transactions.
      *
-     * @var \Doctrine\ODM\MongoDB\UnitOfWork
+     * @var UnitOfWork
      */
     private $unitOfWork;
 
     /**
      * The EventManager associated with this Hydrator
      *
-     * @var \Doctrine\Common\EventManager
+     * @var EventManager
      */
     private $evm;
 
     /**
      * Which algorithm to use to automatically (re)generate hydrator classes.
      *
-     * @var integer
+     * @var int
      */
     private $autoGenerate;
 
@@ -68,22 +86,20 @@ class HydratorFactory
      *
      * @var array
      */
-    private $hydrators = array();
+    private $hydrators = [];
 
     /**
-     * @param DocumentManager $dm
-     * @param EventManager $evm
      * @param string $hydratorDir
      * @param string $hydratorNs
-     * @param integer $autoGenerate
+     * @param int    $autoGenerate
      * @throws HydratorException
      */
     public function __construct(DocumentManager $dm, EventManager $evm, $hydratorDir, $hydratorNs, $autoGenerate)
     {
-        if ( ! $hydratorDir) {
+        if (! $hydratorDir) {
             throw HydratorException::hydratorDirectoryRequired();
         }
-        if ( ! $hydratorNs) {
+        if (! $hydratorNs) {
             throw HydratorException::hydratorNamespaceRequired();
         }
         $this->dm = $dm;
@@ -96,7 +112,6 @@ public function __construct(DocumentManager $dm, EventManager $evm, $hydratorDir
     /**
      * Sets the UnitOfWork instance.
      *
-     * @param UnitOfWork $uow
      */
     public function setUnitOfWork(UnitOfWork $uow)
     {
@@ -107,7 +122,7 @@ public function setUnitOfWork(UnitOfWork $uow)
      * Gets the hydrator object for the given document class.
      *
      * @param string $className
-     * @return \Doctrine\ODM\MongoDB\Hydrator\HydratorInterface $hydrator
+     * @return HydratorInterface $hydrator
      */
     public function getHydratorFor($className)
     {
@@ -118,7 +133,7 @@ public function getHydratorFor($className)
         $fqn = $this->hydratorNamespace . '\\' . $hydratorClassName;
         $class = $this->dm->getClassMetadata($className);
 
-        if ( ! class_exists($fqn, false)) {
+        if (! class_exists($fqn, false)) {
             $fileName = $this->hydratorDir . DIRECTORY_SEPARATOR . $hydratorClassName . '.php';
             switch ($this->autoGenerate) {
                 case Configuration::AUTOGENERATE_NEVER:
@@ -131,7 +146,7 @@ public function getHydratorFor($className)
                     break;
 
                 case Configuration::AUTOGENERATE_FILE_NOT_EXISTS:
-                    if (!file_exists($fileName)) {
+                    if (! file_exists($fileName)) {
                         $this->generateHydratorClass($class, $hydratorClassName, $fileName);
                     }
                     require $fileName;
@@ -149,10 +164,10 @@ public function getHydratorFor($className)
     /**
      * Generates hydrator classes for all given classes.
      *
-     * @param array $classes The classes (ClassMetadata instances) for which to generate hydrators.
-     * @param string $toDir The target directory of the hydrator classes. If not specified, the
-     *                      directory configured on the Configuration of the DocumentManager used
-     *                      by this factory is used.
+     * @param array  $classes The classes (ClassMetadata instances) for which to generate hydrators.
+     * @param string $toDir   The target directory of the hydrator classes. If not specified, the
+     *                        directory configured on the Configuration of the DocumentManager used
+     *                        by this factory is used.
      */
     public function generateHydratorClasses(array $classes, $toDir = null)
     {
@@ -166,7 +181,6 @@ public function generateHydratorClasses(array $classes, $toDir = null)
     }
 
     /**
-     * @param ClassMetadata $class
      * @param string $hydratorClassName
      * @param string $fileName
      */
@@ -177,7 +191,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
         foreach ($class->fieldMappings as $fieldName => $mapping) {
             if (isset($mapping['alsoLoadFields'])) {
                 foreach ($mapping['alsoLoadFields'] as $name) {
-                    $code .= sprintf(<<<EOF
+                    $code .= sprintf(
+                        <<<EOF
 
         /** @AlsoLoad("$name") */
         if (!array_key_exists('%1\$s', \$data) && array_key_exists('$name', \$data)) {
@@ -192,7 +207,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
             }
 
             if ($mapping['type'] === 'date') {
-                $code .= sprintf(<<<EOF
+                $code .= sprintf(
+                    <<<EOF
 
         /** @Field(type="date") */
         if (isset(\$data['%1\$s'])) {
@@ -208,10 +224,9 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                     $mapping['fieldName'],
                     Type::getType($mapping['type'])->closureToPHP()
                 );
-
-
-            } elseif ( ! isset($mapping['association'])) {
-                $code .= sprintf(<<<EOF
+            } elseif (! isset($mapping['association'])) {
+                $code .= sprintf(
+                    <<<EOF
 
         /** @Field(type="{$mapping['type']}") */
         if (isset(\$data['%1\$s']) || (! empty(\$this->class->fieldMappings['%2\$s']['nullable']) && array_key_exists('%1\$s', \$data))) {
@@ -233,7 +248,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                     Type::getType($mapping['type'])->closureToPHP()
                 );
             } elseif ($mapping['association'] === ClassMetadata::REFERENCE_ONE && $mapping['isOwningSide']) {
-                $code .= sprintf(<<<EOF
+                $code .= sprintf(
+                    <<<EOF
 
         /** @ReferenceOne */
         if (isset(\$data['%1\$s'])) {
@@ -254,7 +270,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                 );
             } elseif ($mapping['association'] === ClassMetadata::REFERENCE_ONE && $mapping['isInverseSide']) {
                 if (isset($mapping['repositoryMethod']) && $mapping['repositoryMethod']) {
-                    $code .= sprintf(<<<EOF
+                    $code .= sprintf(
+                        <<<EOF
 
         \$className = \$this->class->fieldMappings['%2\$s']['targetDocument'];
         \$return = \$this->dm->getRepository(\$className)->%3\$s(\$document);
@@ -268,7 +285,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                         $mapping['repositoryMethod']
                     );
                 } else {
-                    $code .= sprintf(<<<EOF
+                    $code .= sprintf(
+                        <<<EOF
 
         \$mapping = \$this->class->fieldMappings['%2\$s'];
         \$className = \$mapping['targetDocument'];
@@ -291,7 +309,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                     );
                 }
             } elseif ($mapping['association'] === ClassMetadata::REFERENCE_MANY || $mapping['association'] === ClassMetadata::EMBED_MANY) {
-                $code .= sprintf(<<<EOF
+                $code .= sprintf(
+                    <<<EOF
 
         /** @Many */
         \$mongoData = isset(\$data['%1\$s']) ? \$data['%1\$s'] : null;
@@ -311,7 +330,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
                     $mapping['fieldName']
                 );
             } elseif ($mapping['association'] === ClassMetadata::EMBED_ONE) {
-                $code .= sprintf(<<<EOF
+                $code .= sprintf(
+                    <<<EOF
 
         /** @EmbedOne */
         if (isset(\$data['%1\$s'])) {
@@ -342,7 +362,8 @@ private function generateHydratorClass(ClassMetadata $class, $hydratorClassName,
         }
 
         $namespace = $this->hydratorNamespace;
-        $code = sprintf(<<<EOF
+        $code = sprintf(
+            <<<EOF
 <?php
 
 namespace $namespace;
@@ -381,17 +402,17 @@ public function hydrate(\$document, \$data, array \$hints = array())
         );
 
         if ($fileName === false) {
-            if ( ! class_exists($namespace . '\\' . $hydratorClassName)) {
+            if (! class_exists($namespace . '\\' . $hydratorClassName)) {
                 eval(substr($code, 5));
             }
         } else {
             $parentDirectory = dirname($fileName);
 
-            if ( ! is_dir($parentDirectory) && (false === @mkdir($parentDirectory, 0775, true))) {
+            if (! is_dir($parentDirectory) && (@mkdir($parentDirectory, 0775, true) === false)) {
                 throw HydratorException::hydratorDirectoryNotWritable();
             }
 
-            if ( ! is_writable($parentDirectory)) {
+            if (! is_writable($parentDirectory)) {
                 throw HydratorException::hydratorDirectoryNotWritable();
             }
 
@@ -405,17 +426,17 @@ public function hydrate(\$document, \$data, array \$hints = array())
     /**
      * Hydrate array of MongoDB document data into the given document object.
      *
-     * @param object $document  The document object to hydrate the data into.
-     * @param array $data The array of document data.
-     * @param array $hints Any hints to account for during reconstitution/lookup of the document.
+     * @param object $document The document object to hydrate the data into.
+     * @param array  $data     The array of document data.
+     * @param array  $hints    Any hints to account for during reconstitution/lookup of the document.
      * @return array $values The array of hydrated values.
      */
-    public function hydrate($document, $data, array $hints = array())
+    public function hydrate($document, $data, array $hints = [])
     {
         $metadata = $this->dm->getClassMetadata(get_class($document));
         // Invoke preLoad lifecycle events and listeners
-        if ( ! empty($metadata->lifecycleCallbacks[Events::preLoad])) {
-            $args = array(new PreLoadEventArgs($document, $this->dm, $data));
+        if (! empty($metadata->lifecycleCallbacks[Events::preLoad])) {
+            $args = [new PreLoadEventArgs($document, $this->dm, $data)];
             $metadata->invokeLifecycleCallbacks(Events::preLoad, $document, $args);
         }
         if ($this->evm->hasListeners(Events::preLoad)) {
@@ -423,7 +444,7 @@ public function hydrate($document, $data, array $hints = array())
         }
 
         // alsoLoadMethods may transform the document before hydration
-        if ( ! empty($metadata->alsoLoadMethods)) {
+        if (! empty($metadata->alsoLoadMethods)) {
             foreach ($metadata->alsoLoadMethods as $method => $fieldNames) {
                 foreach ($fieldNames as $fieldName) {
                     // Invoke the method only once for the first field we find
@@ -443,15 +464,15 @@ public function hydrate($document, $data, array $hints = array())
             // lazy properties may be left uninitialized
             $properties = $document->__getLazyProperties();
             foreach ($properties as $propertyName => $property) {
-                if ( ! isset($document->$propertyName)) {
+                if (! isset($document->$propertyName)) {
                     $document->$propertyName = $properties[$propertyName];
                 }
             }
         }
 
         // Invoke the postLoad lifecycle callbacks and listeners
-        if ( ! empty($metadata->lifecycleCallbacks[Events::postLoad])) {
-            $metadata->invokeLifecycleCallbacks(Events::postLoad, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        if (! empty($metadata->lifecycleCallbacks[Events::postLoad])) {
+            $metadata->invokeLifecycleCallbacks(Events::postLoad, $document, [new LifecycleEventArgs($document, $this->dm)]);
         }
         if ($this->evm->hasListeners(Events::postLoad)) {
             $this->evm->dispatchEvent(Events::postLoad, new LifecycleEventArgs($document, $this->dm));
diff --git a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorInterface.php b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorInterface.php
index 4e7adcd3ba..cd02d25879 100644
--- a/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorInterface.php
+++ b/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorInterface.php
@@ -1,21 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Hydrator;
 
 /**
  * The HydratorInterface defines methods all hydrator need to implement
  *
- * @since       1.0
  */
 interface HydratorInterface
 {
     /**
      * Hydrate array of MongoDB document data into the given document object.
      *
-     * @param object $document  The document object to hydrate the data into.
-     * @param array $data The array of document data.
-     * @param array $hints Any hints to account for during reconstitution/lookup of the document.
+     * @param object $document The document object to hydrate the data into.
+     * @param array  $data     The array of document data.
+     * @param array  $hints    Any hints to account for during reconstitution/lookup of the document.
      * @return array $values The array of hydrated values.
      */
-    public function hydrate($document, $data, array $hints = array());
+    public function hydrate($document, $data, array $hints = []);
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Id/AbstractIdGenerator.php b/lib/Doctrine/ODM/MongoDB/Id/AbstractIdGenerator.php
index 0218f85c30..2b508d19cb 100644
--- a/lib/Doctrine/ODM/MongoDB/Id/AbstractIdGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/Id/AbstractIdGenerator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Id;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -7,14 +9,12 @@
 /**
  * AbstractIdGenerator
  *
- * @since       1.0
  */
 abstract class AbstractIdGenerator
 {
     /**
      * Generates an identifier for a document.
      *
-     * @param \Doctrine\ODM\MongoDB\DocumentManager $dm
      * @param object $document
      * @return mixed
      */
diff --git a/lib/Doctrine/ODM/MongoDB/Id/AlnumGenerator.php b/lib/Doctrine/ODM/MongoDB/Id/AlnumGenerator.php
index 43274ef909..a968080da8 100644
--- a/lib/Doctrine/ODM/MongoDB/Id/AlnumGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/Id/AlnumGenerator.php
@@ -1,8 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Id;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
+use const STR_PAD_LEFT;
+use function bccomp;
+use function bcdiv;
+use function bcmod;
+use function intval;
+use function is_numeric;
+use function str_pad;
+use function strlen;
 
 /**
  * AlnumGenerator is responsible for generating cased alpha-numeric unique identifiers.
@@ -16,11 +26,9 @@
  *
  * The character set used for ID generation can be explicitly set with the "chars" option (e.g. base36, etc.)
  *
- * @since       1.0
  */
 class AlnumGenerator extends IncrementGenerator
 {
-
     protected $pad = null;
 
     protected $awkwardSafeMode = false;
@@ -62,15 +70,15 @@ public function setChars($chars)
     /** @inheritDoc */
     public function generate(DocumentManager $dm, $document)
     {
-        $id = parent::generate($dm, $document);
+        $id = (string) parent::generate($dm, $document);
         $index = $this->awkwardSafeMode ? $this->awkwardSafeChars : $this->chars;
-        $base  = strlen($index);
+        $base  = (string) strlen($index);
 
         $out = '';
         do {
             $out = $index[bcmod($id, $base)] . $out;
             $id = bcdiv($id, $base);
-        } while (bccomp($id, 0) == 1);
+        } while (bccomp($id, '0') === 1);
 
         if (is_numeric($this->pad)) {
             $out = str_pad($out, $this->pad, '0', STR_PAD_LEFT);
diff --git a/lib/Doctrine/ODM/MongoDB/Id/AutoGenerator.php b/lib/Doctrine/ODM/MongoDB/Id/AutoGenerator.php
index 910cd97cb0..25242ee5d5 100644
--- a/lib/Doctrine/ODM/MongoDB/Id/AutoGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/Id/AutoGenerator.php
@@ -1,19 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Id;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
+use MongoDB\BSON\ObjectId;
 
 /**
  * AutoGenerator generates a native ObjectId
  *
- * @since       1.0
  */
 class AutoGenerator extends AbstractIdGenerator
 {
     /** @inheritDoc */
     public function generate(DocumentManager $dm, $document)
     {
-        return new \MongoDB\BSON\ObjectId();
+        return new ObjectId();
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Id/IncrementGenerator.php b/lib/Doctrine/ODM/MongoDB/Id/IncrementGenerator.php
index b5beb28dd5..2af78d7d53 100644
--- a/lib/Doctrine/ODM/MongoDB/Id/IncrementGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/Id/IncrementGenerator.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Id;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use MongoDB\Operation\FindOneAndUpdate;
+use function get_class;
 
 /**
  * IncrementGenerator is responsible for generating auto increment identifiers. It uses
@@ -16,7 +19,6 @@
  * collection. If not specified it defaults to the name of the collection for the
  * document.
  *
- * @since       1.0
  */
 class IncrementGenerator extends AbstractIdGenerator
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Id/UuidGenerator.php b/lib/Doctrine/ODM/MongoDB/Id/UuidGenerator.php
index 2097e64abe..476480ef96 100644
--- a/lib/Doctrine/ODM/MongoDB/Id/UuidGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/Id/UuidGenerator.php
@@ -1,13 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Id;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
+use function chr;
+use function hexdec;
+use function mt_rand;
+use function php_uname;
+use function preg_match;
+use function sha1;
+use function sprintf;
+use function str_replace;
+use function strlen;
+use function substr;
 
 /**
  * Generates UUIDs.
  *
- * @since       1.0
  */
 class UuidGenerator extends AbstractIdGenerator
 {
@@ -42,7 +53,7 @@ public function getSalt()
      * Checks that a given string is a valid uuid.
      *
      * @param string $uuid The string to check.
-     * @return boolean
+     * @return bool
      */
     public function isValid($uuid)
     {
@@ -53,8 +64,8 @@ public function isValid($uuid)
     /**
      * Generates a new UUID
      *
-     * @param DocumentManager $dm Not used.
-     * @param object $document Not used.
+     * @param DocumentManager $dm       Not used.
+     * @param object          $document Not used.
      * @return string UUID
      */
     public function generate(DocumentManager $dm, $document)
@@ -95,18 +106,18 @@ public function generateV4()
      * Generates a v5 UUID
      *
      * @param string $namespace The UUID to seed with
-     * @param string $salt The string to salt this new UUID with
+     * @param string $salt      The string to salt this new UUID with
      * @throws \Exception when the provided namespace is invalid
      * @return string
      */
     public function generateV5($namespace, $salt)
     {
-        if ( ! $this->isValid($namespace)) {
+        if (! $this->isValid($namespace)) {
             throw new \Exception('Provided $namespace is invalid: ' . $namespace);
         }
 
         // Get hexadecimal components of namespace
-        $nhex = str_replace(array('-', '{', '}'), '', $namespace);
+        $nhex = str_replace(['-', '{', '}'], '', $namespace);
 
         // Binary Value
         $nstr = '';
diff --git a/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php b/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
index 0e65cff23a..11180c37f1 100644
--- a/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
+++ b/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
@@ -1,7 +1,14 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Iterator;
 
+use function current;
+use function key;
+use function next;
+use function reset;
+
 /**
  * Iterator for wrapping a Traversable and caching its results.
  *
@@ -19,7 +26,7 @@ final class CachingIterator implements Iterator
     private $iteratorExhausted = false;
 
     /**
-     * Constructor.
+     *
      *
      * Initialize the iterator and stores the first item in the cache. This
      * effectively rewinds the Traversable and the wrapping Generator, which
@@ -27,7 +34,6 @@ final class CachingIterator implements Iterator
      * behavior of the SPL iterators and allows users to omit an explicit call
      * to rewind() before using the other methods.
      *
-     * @param \Traversable $iterator
      */
     public function __construct(\Traversable $iterator)
     {
@@ -62,11 +68,10 @@ public function key()
 
     /**
      * @see http://php.net/iterator.next
-     * @return void
      */
     public function next()
     {
-        if ( ! $this->iteratorExhausted) {
+        if (! $this->iteratorExhausted) {
             $this->iterator->next();
             $this->storeCurrentItem();
         }
@@ -76,7 +81,6 @@ public function next()
 
     /**
      * @see http://php.net/iterator.rewind
-     * @return void
      */
     public function rewind()
     {
@@ -93,7 +97,7 @@ public function rewind()
     /**
      *
      * @see http://php.net/iterator.valid
-     * @return boolean
+     * @return bool
      */
     public function valid()
     {
@@ -105,7 +109,7 @@ public function valid()
      */
     private function exhaustIterator()
     {
-        while ( ! $this->iteratorExhausted) {
+        while (! $this->iteratorExhausted) {
             $this->next();
         }
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Iterator/HydratingIterator.php b/lib/Doctrine/ODM/MongoDB/Iterator/HydratingIterator.php
index 7727d9da0f..674367b2c9 100644
--- a/lib/Doctrine/ODM/MongoDB/Iterator/HydratingIterator.php
+++ b/lib/Doctrine/ODM/MongoDB/Iterator/HydratingIterator.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Iterator;
 
@@ -45,7 +47,6 @@ public function key()
 
     /**
      * @see http://php.net/iterator.next
-     * @return void
      */
     public function next()
     {
@@ -54,7 +55,6 @@ public function next()
 
     /**
      * @see http://php.net/iterator.rewind
-     * @return void
      */
     public function rewind()
     {
@@ -63,7 +63,7 @@ public function rewind()
 
     /**
      * @see http://php.net/iterator.valid
-     * @return boolean
+     * @return bool
      */
     public function valid()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Iterator/Iterator.php b/lib/Doctrine/ODM/MongoDB/Iterator/Iterator.php
index cd357378ca..d58fba5565 100644
--- a/lib/Doctrine/ODM/MongoDB/Iterator/Iterator.php
+++ b/lib/Doctrine/ODM/MongoDB/Iterator/Iterator.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Iterator;
 
diff --git a/lib/Doctrine/ODM/MongoDB/Iterator/PrimingIterator.php b/lib/Doctrine/ODM/MongoDB/Iterator/PrimingIterator.php
index ef41b48703..2daae42c35 100644
--- a/lib/Doctrine/ODM/MongoDB/Iterator/PrimingIterator.php
+++ b/lib/Doctrine/ODM/MongoDB/Iterator/PrimingIterator.php
@@ -1,9 +1,13 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Iterator;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Query\ReferencePrimer;
+use function is_callable;
+use function iterator_to_array;
 
 final class PrimingIterator implements Iterator
 {
diff --git a/lib/Doctrine/ODM/MongoDB/LockException.php b/lib/Doctrine/ODM/MongoDB/LockException.php
index b3b7791a7a..fb4154929a 100644
--- a/lib/Doctrine/ODM/MongoDB/LockException.php
+++ b/lib/Doctrine/ODM/MongoDB/LockException.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 /**
  * LockException
  *
- * @since 1.0
  */
 class LockException extends MongoDBException
 {
@@ -34,7 +35,7 @@ public static function lockFailed($document)
 
     public static function lockFailedVersionMissmatch($document, $expectedLockVersion, $actualLockVersion)
     {
-        return new self('The optimistic lock failed, version ' . $expectedLockVersion . ' was expected, but is actually '.$actualLockVersion, $document);
+        return new self('The optimistic lock failed, version ' . $expectedLockVersion . ' was expected, but is actually ' . $actualLockVersion, $document);
     }
 
     public static function notVersioned($documentName)
@@ -44,11 +45,11 @@ public static function notVersioned($documentName)
 
     public static function invalidLockFieldType($type)
     {
-        return new self('Invalid lock field type '.$type.'. Lock field must be int.');
+        return new self('Invalid lock field type ' . $type . '. Lock field must be int.');
     }
 
     public static function invalidVersionFieldType($type)
     {
-        return new self('Invalid version field type '.$type.'. Version field must be int or date.');
+        return new self('Invalid version field type ' . $type . '. Version field must be int or date.');
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/LockMode.php b/lib/Doctrine/ODM/MongoDB/LockMode.php
index c1f97fc660..d9d84afee7 100644
--- a/lib/Doctrine/ODM/MongoDB/LockMode.php
+++ b/lib/Doctrine/ODM/MongoDB/LockMode.php
@@ -1,18 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 /**
  * Contains all MongoDB ODM LockModes
  *
- * @since       1.0
  */
 class LockMode
 {
-    const NONE = 0;
-    const OPTIMISTIC = 1;
-    const PESSIMISTIC_READ = 2;
-    const PESSIMISTIC_WRITE = 4;
+    public const NONE = 0;
+    public const OPTIMISTIC = 1;
+    public const PESSIMISTIC_READ = 2;
+    public const PESSIMISTIC_WRITE = 4;
 
-    final private function __construct() { }
+    final private function __construct()
+    {
+    }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractDocument.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractDocument.php
index 5b371652c2..a0a4fc8c79 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractDocument.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractField.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractField.php
index 4c89ed349f..e995629832 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractField.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractField.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
+use function get_class;
+use function sprintf;
 
 abstract class AbstractField extends Annotation
 {
     public $name;
     public $type = 'string';
     public $nullable = false;
-    public $options = array();
+    public $options = [];
     public $strategy;
 
     /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractIndex.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractIndex.php
index 5fbbef16a9..c516daafdd 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractIndex.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AbstractIndex.php
@@ -1,12 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
 
 abstract class AbstractIndex extends Annotation
 {
-    public $keys = array();
+    public $keys = [];
     public $name;
     public $dropDups;
     public $background;
@@ -14,6 +16,6 @@ abstract class AbstractIndex extends Annotation
     public $order;
     public $unique = false;
     public $sparse = false;
-    public $options = array();
-    public $partialFilterExpression = array();
+    public $options = [];
+    public $partialFilterExpression = [];
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AlsoLoad.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AlsoLoad.php
index eefcc1272b..0e7a942b4f 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AlsoLoad.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/AlsoLoad.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ChangeTrackingPolicy.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ChangeTrackingPolicy.php
index 52cf3b44f6..4f424c748d 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ChangeTrackingPolicy.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ChangeTrackingPolicy.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DefaultDiscriminatorValue.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DefaultDiscriminatorValue.php
index b1fea215be..3505b4c3f6 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DefaultDiscriminatorValue.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DefaultDiscriminatorValue.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorField.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorField.php
index f5c7bc75a0..6842f3cd1c 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorField.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorField.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorMap.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorMap.php
index e1206884a8..e67d6e9bde 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorMap.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorMap.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorValue.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorValue.php
index 8190958f5c..f759bbc353 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorValue.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorValue.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Document.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Document.php
index cfde02d977..6b33014876 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Document.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Document.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
@@ -12,7 +14,7 @@ final class Document extends AbstractDocument
     public $db;
     public $collection;
     public $repositoryClass;
-    public $indexes = array();
+    public $indexes = [];
     public $readOnly = false;
     public $shardKey;
     public $writeConcern;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedMany.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedMany.php
index 6ae177cb4e..977dff2f1b 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedMany.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedMany.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedOne.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedOne.php
index cbcfb13685..4e35a53c6a 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedOne.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbedOne.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbeddedDocument.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbeddedDocument.php
index 30a5dd5336..750dc3161e 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbeddedDocument.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/EmbeddedDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
@@ -9,5 +11,5 @@
  */
 final class EmbeddedDocument extends AbstractDocument
 {
-    public $indexes = array();
+    public $indexes = [];
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Field.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Field.php
index 1f19fa2fb1..f49f4a23e5 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Field.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Field.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/HasLifecycleCallbacks.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/HasLifecycleCallbacks.php
index 6e55c042cf..8ebd447d8e 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/HasLifecycleCallbacks.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/HasLifecycleCallbacks.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Id.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Id.php
index 927e894249..c0271eddf9 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Id.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Id.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Index.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Index.php
index 52cfc96d76..c04ff19003 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Index.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Index.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Indexes.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Indexes.php
index a6c88aeacd..2d56db8020 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Indexes.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Indexes.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Inheritance.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Inheritance.php
index c2c6710d55..b50319cf58 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Inheritance.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Inheritance.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
@@ -12,7 +14,7 @@
 final class Inheritance extends Annotation
 {
     public $type = 'NONE';
-    public $discriminatorMap = array();
+    public $discriminatorMap = [];
     public $discriminatorField;
     public $defaultDiscriminatorValue;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/InheritanceType.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/InheritanceType.php
index 96b2b5eff9..600f2d7e12 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/InheritanceType.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/InheritanceType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Lock.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Lock.php
index 93ae68f691..c6954dfe01 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Lock.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Lock.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/MappedSuperclass.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/MappedSuperclass.php
index e2a56f2ab5..c17b45ebf3 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/MappedSuperclass.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/MappedSuperclass.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/NotSaved.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/NotSaved.php
index 314e66da7c..0d7162227d 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/NotSaved.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/NotSaved.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostLoad.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostLoad.php
index d1d788da7c..b7d6d4a554 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostLoad.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostLoad.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostPersist.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostPersist.php
index 9be2f98cbf..7211cd4c24 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostPersist.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostPersist.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostRemove.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostRemove.php
index eba744ac2b..a6730e611d 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostRemove.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostRemove.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostUpdate.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostUpdate.php
index 56400e859e..6d1aa66d57 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostUpdate.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PostUpdate.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreFlush.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreFlush.php
index 848ce7be7d..cd7b846ae7 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreFlush.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreFlush.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreLoad.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreLoad.php
index b6aa0209f8..34835dbe12 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreLoad.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreLoad.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PrePersist.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PrePersist.php
index a39867717a..f81cb84769 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PrePersist.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PrePersist.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreRemove.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreRemove.php
index 1dfbebb4ed..85cf9f8f3f 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreRemove.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreRemove.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreUpdate.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreUpdate.php
index 2b51ef16f2..9ae419359c 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreUpdate.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/PreUpdate.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/QueryResultDocument.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/QueryResultDocument.php
index f1b62c5b49..7bfb4b04d9 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/QueryResultDocument.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/QueryResultDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /** @Annotation */
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReadPreference.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReadPreference.php
index 4dd4eebbf3..e8d4f2323a 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReadPreference.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReadPreference.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceMany.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceMany.php
index e951de1991..7f2eb2d889 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceMany.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceMany.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceOne.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceOne.php
index eafbf31f22..014e937e53 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceOne.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ReferenceOne.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
@@ -23,8 +25,8 @@ final class ReferenceOne extends AbstractField
     public $inversedBy;
     public $mappedBy;
     public $repositoryMethod;
-    public $sort = array();
-    public $criteria = array();
+    public $sort = [];
+    public $criteria = [];
     public $limit;
     public $skip;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ShardKey.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ShardKey.php
index 219908458d..196ce53bd8 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ShardKey.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/ShardKey.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
@@ -7,7 +9,7 @@
 /** @Annotation */
 final class ShardKey extends Annotation
 {
-    public $keys = array();
+    public $keys = [];
     public $unique;
     public $numInitialChunks;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/UniqueIndex.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/UniqueIndex.php
index 70855f59c3..124595d811 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/UniqueIndex.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/UniqueIndex.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 /**
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Version.php b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Version.php
index d353827c05..ac194cb103 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Version.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Annotations/Version.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Annotations;
 
 use Doctrine\Common\Annotations\Annotation;
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
index a7f74a97a8..97af1b7f32 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
@@ -1,14 +1,40 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping;
 
 use Doctrine\Common\Persistence\Mapping\ClassMetadata as BaseClassMetadata;
 use Doctrine\Instantiator\Instantiator;
-use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use Doctrine\Instantiator\InstantiatorInterface;
+use Doctrine\ODM\MongoDB\Id\AbstractIdGenerator;
 use Doctrine\ODM\MongoDB\LockException;
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\Types\Type;
+use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
 use InvalidArgumentException;
+use MongoDB\BSON\ObjectId;
+use function array_filter;
+use function array_key_exists;
+use function array_keys;
+use function array_map;
+use function array_pop;
+use function call_user_func_array;
+use function class_exists;
+use function constant;
+use function count;
+use function get_class;
+use function in_array;
+use function is_array;
+use function is_null;
+use function is_string;
+use function is_subclass_of;
+use function ltrim;
+use function sprintf;
+use function strlen;
+use function strpos;
+use function strtolower;
+use function strtoupper;
 
 /**
  * A <tt>ClassMetadata</tt> instance holds all the object-document mapping metadata
@@ -24,7 +50,6 @@
  *    get the whole class name, namespace inclusive, prepended to every property in
  *    the serialized representation).
  *
- * @since       1.0
  */
 class ClassMetadata implements BaseClassMetadata
 {
@@ -32,24 +57,24 @@ class ClassMetadata implements BaseClassMetadata
     /**
      * AUTO means Doctrine will automatically create a new \MongoDB\BSON\ObjectId instance for us.
      */
-    const GENERATOR_TYPE_AUTO = 1;
+    public const GENERATOR_TYPE_AUTO = 1;
 
     /**
      * INCREMENT means a separate collection is used for maintaining and incrementing id generation.
      * Offers full portability.
      */
-    const GENERATOR_TYPE_INCREMENT = 2;
+    public const GENERATOR_TYPE_INCREMENT = 2;
 
     /**
      * UUID means Doctrine will generate a uuid for us.
      */
-    const GENERATOR_TYPE_UUID = 3;
+    public const GENERATOR_TYPE_UUID = 3;
 
     /**
      * ALNUM means Doctrine will generate Alpha-numeric string identifiers, using the INCREMENT
      * generator to ensure identifier uniqueness
      */
-    const GENERATOR_TYPE_ALNUM = 4;
+    public const GENERATOR_TYPE_ALNUM = 4;
 
     /**
      * CUSTOM means Doctrine expect a class parameter. It will then try to initiate that class
@@ -59,13 +84,13 @@ class ClassMetadata implements BaseClassMetadata
      *
      * The class  will have to be a subtype of AbstractIdGenerator.
      */
-    const GENERATOR_TYPE_CUSTOM = 5;
+    public const GENERATOR_TYPE_CUSTOM = 5;
 
     /**
      * NONE means Doctrine will not generate any id for us and you are responsible for manually
      * assigning an id.
      */
-    const GENERATOR_TYPE_NONE = 6;
+    public const GENERATOR_TYPE_NONE = 6;
 
     /**
      * Default discriminator field name.
@@ -73,41 +98,41 @@ class ClassMetadata implements BaseClassMetadata
      * This is used for associations value for associations where a that do not define a "targetDocument" or
      * "discriminatorField" option in their mapping.
      */
-    const DEFAULT_DISCRIMINATOR_FIELD = '_doctrine_class_name';
+    public const DEFAULT_DISCRIMINATOR_FIELD = '_doctrine_class_name';
 
-    const REFERENCE_ONE = 1;
-    const REFERENCE_MANY = 2;
-    const EMBED_ONE = 3;
-    const EMBED_MANY = 4;
-    const MANY = 'many';
-    const ONE = 'one';
+    public const REFERENCE_ONE = 1;
+    public const REFERENCE_MANY = 2;
+    public const EMBED_ONE = 3;
+    public const EMBED_MANY = 4;
+    public const MANY = 'many';
+    public const ONE = 'one';
 
     /**
      * The types of storeAs references
      */
-    const REFERENCE_STORE_AS_ID = 'id';
-    const REFERENCE_STORE_AS_DB_REF = 'dbRef';
-    const REFERENCE_STORE_AS_DB_REF_WITH_DB = 'dbRefWithDb';
-    const REFERENCE_STORE_AS_REF = 'ref';
+    public const REFERENCE_STORE_AS_ID = 'id';
+    public const REFERENCE_STORE_AS_DB_REF = 'dbRef';
+    public const REFERENCE_STORE_AS_DB_REF_WITH_DB = 'dbRefWithDb';
+    public const REFERENCE_STORE_AS_REF = 'ref';
 
     /* The inheritance mapping types */
     /**
      * NONE means the class does not participate in an inheritance hierarchy
      * and therefore does not need an inheritance mapping type.
      */
-    const INHERITANCE_TYPE_NONE = 1;
+    public const INHERITANCE_TYPE_NONE = 1;
 
     /**
      * SINGLE_COLLECTION means the class will be persisted according to the rules of
      * <tt>Single Collection Inheritance</tt>.
      */
-    const INHERITANCE_TYPE_SINGLE_COLLECTION = 2;
+    public const INHERITANCE_TYPE_SINGLE_COLLECTION = 2;
 
     /**
      * COLLECTION_PER_CLASS means the class will be persisted according to the rules
      * of <tt>Concrete Collection Inheritance</tt>.
      */
-    const INHERITANCE_TYPE_COLLECTION_PER_CLASS = 3;
+    public const INHERITANCE_TYPE_COLLECTION_PER_CLASS = 3;
 
     /**
      * DEFERRED_IMPLICIT means that changes of entities are calculated at commit-time
@@ -116,38 +141,38 @@ class ClassMetadata implements BaseClassMetadata
      *
      * This is the default change tracking policy.
      */
-    const CHANGETRACKING_DEFERRED_IMPLICIT = 1;
+    public const CHANGETRACKING_DEFERRED_IMPLICIT = 1;
 
     /**
      * DEFERRED_EXPLICIT means that changes of entities are calculated at commit-time
      * by doing a property-by-property comparison with the original data. This will
      * be done only for entities that were explicitly saved (through persist() or a cascade).
      */
-    const CHANGETRACKING_DEFERRED_EXPLICIT = 2;
+    public const CHANGETRACKING_DEFERRED_EXPLICIT = 2;
 
     /**
      * NOTIFY means that Doctrine relies on the entities sending out notifications
      * when their properties change. Such entity classes must implement
      * the <tt>NotifyPropertyChanged</tt> interface.
      */
-    const CHANGETRACKING_NOTIFY = 3;
+    public const CHANGETRACKING_NOTIFY = 3;
 
     /**
      * SET means that fields will be written to the database using a $set operator
      */
-    const STORAGE_STRATEGY_SET = 'set';
+    public const STORAGE_STRATEGY_SET = 'set';
 
     /**
      * INCREMENT means that fields will be written to the database by calculating
      * the difference and using the $inc operator
      */
-    const STORAGE_STRATEGY_INCREMENT = 'increment';
+    public const STORAGE_STRATEGY_INCREMENT = 'increment';
 
-    const STORAGE_STRATEGY_PUSH_ALL = 'pushAll';
-    const STORAGE_STRATEGY_ADD_TO_SET = 'addToSet';
-    const STORAGE_STRATEGY_ATOMIC_SET = 'atomicSet';
-    const STORAGE_STRATEGY_ATOMIC_SET_ARRAY = 'atomicSetArray';
-    const STORAGE_STRATEGY_SET_ARRAY = 'setArray';
+    public const STORAGE_STRATEGY_PUSH_ALL = 'pushAll';
+    public const STORAGE_STRATEGY_ADD_TO_SET = 'addToSet';
+    public const STORAGE_STRATEGY_ATOMIC_SET = 'atomicSet';
+    public const STORAGE_STRATEGY_ATOMIC_SET_ARRAY = 'atomicSetArray';
+    public const STORAGE_STRATEGY_SET_ARRAY = 'setArray';
 
     /**
      * READ-ONLY: The name of the mongo database the document is mapped to.
@@ -198,7 +223,7 @@ class ClassMetadata implements BaseClassMetadata
     /**
      * READ-ONLY: The array of indexes for the document collection.
      */
-    public $indexes = array();
+    public $indexes = [];
 
     /**
      * READ-ONLY: Keys and options describing shard key. Only for sharded collections.
@@ -240,26 +265,26 @@ class ClassMetadata implements BaseClassMetadata
      *
      * @var array
      */
-    public $parentClasses = array();
+    public $parentClasses = [];
 
     /**
      * READ-ONLY: The names of all subclasses (descendants).
      *
      * @var array
      */
-    public $subClasses = array();
+    public $subClasses = [];
 
     /**
      * The ReflectionProperty instances of the mapped class.
      *
      * @var \ReflectionProperty[]
      */
-    public $reflFields = array();
+    public $reflFields = [];
 
     /**
      * READ-ONLY: The inheritance mapping type used by the class.
      *
-     * @var integer
+     * @var int
      */
     public $inheritanceType = self::INHERITANCE_TYPE_NONE;
 
@@ -275,12 +300,12 @@ class ClassMetadata implements BaseClassMetadata
      *
      * @var array
      */
-    public $generatorOptions = array();
+    public $generatorOptions = [];
 
     /**
      * READ-ONLY: The ID generator used for generating IDs for this class.
      *
-     * @var \Doctrine\ODM\MongoDB\Id\AbstractIdGenerator
+     * @var AbstractIdGenerator
      */
     public $idGenerator;
 
@@ -299,7 +324,7 @@ class ClassMetadata implements BaseClassMetadata
      *
      * @var array
      */
-    public $fieldMappings = array();
+    public $fieldMappings = [];
 
     /**
      * READ-ONLY: The association mappings of the class.
@@ -307,21 +332,21 @@ class ClassMetadata implements BaseClassMetadata
      *
      * @var array
      */
-    public $associationMappings = array();
+    public $associationMappings = [];
 
     /**
      * READ-ONLY: Array of fields to also load with a given method.
      *
      * @var array
      */
-    public $alsoLoadMethods = array();
+    public $alsoLoadMethods = [];
 
     /**
      * READ-ONLY: The registered lifecycle callbacks for documents of this class.
      *
      * @var array
      */
-    public $lifecycleCallbacks = array();
+    public $lifecycleCallbacks = [];
 
     /**
      * READ-ONLY: The discriminator value of this class.
@@ -343,7 +368,7 @@ class ClassMetadata implements BaseClassMetadata
      * @var mixed
      * @see discriminatorField
      */
-    public $discriminatorMap = array();
+    public $discriminatorMap = [];
 
     /**
      * READ-ONLY: The definition of the discriminator field used in SINGLE_COLLECTION
@@ -364,28 +389,28 @@ class ClassMetadata implements BaseClassMetadata
     /**
      * READ-ONLY: Whether this class describes the mapping of a mapped superclass.
      *
-     * @var boolean
+     * @var bool
      */
     public $isMappedSuperclass = false;
 
     /**
      * READ-ONLY: Whether this class describes the mapping of a embedded document.
      *
-     * @var boolean
+     * @var bool
      */
     public $isEmbeddedDocument = false;
 
     /**
      * READ-ONLY: Whether this class describes the mapping of an aggregation result document.
      *
-     * @var boolean
+     * @var bool
      */
     public $isQueryResultDocument = false;
 
     /**
      * READ-ONLY: The policy used for change-tracking on entities of this class.
      *
-     * @var integer
+     * @var int
      */
     public $changeTrackingPolicy = self::CHANGETRACKING_DEFERRED_IMPLICIT;
 
@@ -393,7 +418,7 @@ class ClassMetadata implements BaseClassMetadata
      * READ-ONLY: A flag for whether or not instances of this class are to be versioned
      * with optimistic locking.
      *
-     * @var boolean $isVersioned
+     * @var bool $isVersioned
      */
     public $isVersioned;
 
@@ -408,7 +433,7 @@ class ClassMetadata implements BaseClassMetadata
      * READ-ONLY: A flag for whether or not instances of this class are to allow pessimistic
      * locking.
      *
-     * @var boolean $isLockable
+     * @var bool $isLockable
      */
     public $isLockable;
 
@@ -434,7 +459,7 @@ class ClassMetadata implements BaseClassMetadata
     public $isReadOnly;
 
     /**
-     * @var \Doctrine\Instantiator\InstantiatorInterface|null
+     * @var InstantiatorInterface|null
      */
     private $instantiator;
 
@@ -463,7 +488,7 @@ public function __construct($documentName)
      */
     public static function getReferenceId($reference, $storeAs)
     {
-        return $storeAs === ClassMetadata::REFERENCE_STORE_AS_ID ? $reference : $reference[ClassMetadata::getReferencePrefix($storeAs) . 'id'];
+        return $storeAs === self::REFERENCE_STORE_AS_ID ? $reference : $reference[self::getReferencePrefix($storeAs) . 'id'];
     }
 
     /**
@@ -473,11 +498,11 @@ public static function getReferenceId($reference, $storeAs)
      */
     private static function getReferencePrefix($storeAs)
     {
-        if (!in_array($storeAs, [ClassMetadata::REFERENCE_STORE_AS_REF, ClassMetadata::REFERENCE_STORE_AS_DB_REF, ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB])) {
+        if (! in_array($storeAs, [self::REFERENCE_STORE_AS_REF, self::REFERENCE_STORE_AS_DB_REF, self::REFERENCE_STORE_AS_DB_REF_WITH_DB])) {
             throw new \LogicException('Can only get a reference prefix for DBRef and reference arrays');
         }
 
-        return $storeAs === ClassMetadata::REFERENCE_STORE_AS_REF ? '' : '$';
+        return $storeAs === self::REFERENCE_STORE_AS_REF ? '' : '$';
     }
 
     /**
@@ -489,7 +514,7 @@ private static function getReferencePrefix($storeAs)
      */
     public static function getReferenceFieldName($storeAs, $pathPrefix = '')
     {
-        if ($storeAs === ClassMetadata::REFERENCE_STORE_AS_ID) {
+        if ($storeAs === self::REFERENCE_STORE_AS_ID) {
             return $pathPrefix;
         }
 
@@ -501,7 +526,7 @@ public static function getReferenceFieldName($storeAs, $pathPrefix = '')
      */
     public function getReflectionClass()
     {
-        if ( ! $this->reflClass) {
+        if (! $this->reflClass) {
             $this->reflClass = new \ReflectionClass($this->name);
         }
 
@@ -535,7 +560,7 @@ public function setIdentifier($identifier)
      */
     public function getIdentifier()
     {
-        return array($this->identifier);
+        return [$this->identifier];
     }
 
     /**
@@ -546,7 +571,7 @@ public function getIdentifier()
      */
     public function getIdentifierFieldNames()
     {
-        return array($this->identifier);
+        return [$this->identifier];
     }
 
     /**
@@ -560,7 +585,7 @@ public function hasField($fieldName)
     /**
      * Sets the inheritance type used by the class and it's subclasses.
      *
-     * @param integer $type
+     * @param int $type
      */
     public function setInheritanceType($type)
     {
@@ -572,7 +597,7 @@ public function setInheritanceType($type)
      *
      * @param  string $fieldName
      *
-     * @return boolean TRUE if the field is inherited, FALSE otherwise.
+     * @return bool TRUE if the field is inherited, FALSE otherwise.
      */
     public function isInheritedField($fieldName)
     {
@@ -607,9 +632,9 @@ public function setCustomRepositoryClass($repositoryClassName)
      * @throws \InvalidArgumentException if document class is not this class or
      *                                   a Proxy of this class
      */
-    public function invokeLifecycleCallbacks($event, $document, array $arguments = null)
+    public function invokeLifecycleCallbacks($event, $document, ?array $arguments = null)
     {
-        if ( ! $document instanceof $this->name) {
+        if (! $document instanceof $this->name) {
             throw new \InvalidArgumentException(sprintf('Expected document class "%s"; found: "%s"', $this->name, get_class($document)));
         }
 
@@ -619,7 +644,7 @@ public function invokeLifecycleCallbacks($event, $document, array $arguments = n
 
         foreach ($this->lifecycleCallbacks[$event] as $callback) {
             if ($arguments !== null) {
-                call_user_func_array(array($document, $callback), $arguments);
+                call_user_func_array([$document, $callback], $arguments);
             } else {
                 $document->$callback();
             }
@@ -631,7 +656,7 @@ public function invokeLifecycleCallbacks($event, $document, array $arguments = n
      *
      * @param string $event Lifecycle event
      *
-     * @return boolean
+     * @return bool
      */
     public function hasLifecycleCallbacks($event)
     {
@@ -646,7 +671,7 @@ public function hasLifecycleCallbacks($event)
      */
     public function getLifecycleCallbacks($event)
     {
-        return $this->lifecycleCallbacks[$event] ?? array();
+        return $this->lifecycleCallbacks[$event] ?? [];
     }
 
     /**
@@ -689,7 +714,7 @@ public function setLifecycleCallbacks(array $callbacks)
      */
     public function registerAlsoLoadMethod($method, $fields)
     {
-        $this->alsoLoadMethods[$method] = is_array($fields) ? $fields : array($fields);
+        $this->alsoLoadMethods[$method] = is_array($fields) ? $fields : [$fields];
     }
 
     /**
@@ -734,7 +759,7 @@ public function setDiscriminatorField($discriminatorField)
         }
 
         foreach ($this->fieldMappings as $fieldMapping) {
-            if ($discriminatorField == $fieldMapping['name']) {
+            if ($discriminatorField === $fieldMapping['name']) {
                 throw MappingException::discriminatorFieldConflict($this->name, $discriminatorField);
             }
         }
@@ -757,10 +782,10 @@ public function setDiscriminatorMap(array $map)
                 $className = $this->namespace . '\\' . $className;
             }
             $this->discriminatorMap[$value] = $className;
-            if ($this->name == $className) {
+            if ($this->name === $className) {
                 $this->discriminatorValue = $value;
             } else {
-                if ( ! class_exists($className)) {
+                if (! class_exists($className)) {
                     throw MappingException::invalidClassInDiscriminatorMap($className, $this->name);
                 }
                 if (is_subclass_of($className, $this->name)) {
@@ -786,7 +811,7 @@ public function setDefaultDiscriminatorValue($defaultDiscriminatorValue)
             return;
         }
 
-        if (!array_key_exists($defaultDiscriminatorValue, $this->discriminatorMap)) {
+        if (! array_key_exists($defaultDiscriminatorValue, $this->discriminatorMap)) {
             throw MappingException::invalidDiscriminatorValue($defaultDiscriminatorValue, $this->name);
         }
 
@@ -809,14 +834,14 @@ public function setDiscriminatorValue($value)
     /**
      * Add a index for this Document.
      *
-     * @param array $keys Array of keys for the index.
+     * @param array $keys    Array of keys for the index.
      * @param array $options Array of options for the index.
      */
-    public function addIndex($keys, array $options = array())
+    public function addIndex($keys, array $options = [])
     {
-        $this->indexes[] = array(
-            'keys' => array_map(function($value) {
-                if ($value == 1 || $value == -1) {
+        $this->indexes[] = [
+            'keys' => array_map(function ($value) {
+                if ($value === 1 || $value === -1) {
                     return (int) $value;
                 }
                 if (is_string($value)) {
@@ -829,8 +854,8 @@ public function addIndex($keys, array $options = array())
                 }
                 return $value;
             }, $keys),
-            'options' => $options
-        );
+            'options' => $options,
+        ];
     }
 
     /**
@@ -846,7 +871,7 @@ public function getIndexes()
     /**
      * Checks whether this document has indexes or not.
      *
-     * @return boolean
+     * @return bool
      */
     public function hasIndexes()
     {
@@ -856,14 +881,14 @@ public function hasIndexes()
     /**
      * Set shard key for this Document.
      *
-     * @param array $keys Array of document keys.
+     * @param array $keys    Array of document keys.
      * @param array $options Array of sharding options.
      *
      * @throws MappingException
      */
-    public function setShardKey(array $keys, array $options = array())
+    public function setShardKey(array $keys, array $options = [])
     {
-        if ($this->inheritanceType === self::INHERITANCE_TYPE_SINGLE_COLLECTION && !is_null($this->shardKey)) {
+        if ($this->inheritanceType === self::INHERITANCE_TYPE_SINGLE_COLLECTION && ! is_null($this->shardKey)) {
             throw MappingException::shardKeyInSingleCollInheritanceSubclass($this->getName());
         }
 
@@ -885,9 +910,9 @@ public function setShardKey(array $keys, array $options = array())
             }
         }
 
-        $this->shardKey = array(
-            'keys' => array_map(function($value) {
-                if ($value == 1 || $value == -1) {
+        $this->shardKey = [
+            'keys' => array_map(function ($value) {
+                if ($value === 1 || $value === -1) {
                     return (int) $value;
                 }
                 if (is_string($value)) {
@@ -900,8 +925,8 @@ public function setShardKey(array $keys, array $options = array())
                 }
                 return $value;
             }, $keys),
-            'options' => $options
-        );
+            'options' => $options,
+        ];
     }
 
     /**
@@ -925,7 +950,7 @@ public function isSharded()
     /**
      * Sets the read preference used by this class.
      *
-     * @param string $readPreference
+     * @param string     $readPreference
      * @param array|null $tags
      */
     public function setReadPreference($readPreference, $tags)
@@ -965,7 +990,7 @@ public function hasWriteConcern()
     /**
      * Sets the change tracking policy used by this class.
      *
-     * @param integer $policy
+     * @param int $policy
      */
     public function setChangeTrackingPolicy($policy)
     {
@@ -975,31 +1000,31 @@ public function setChangeTrackingPolicy($policy)
     /**
      * Whether the change tracking policy of this class is "deferred explicit".
      *
-     * @return boolean
+     * @return bool
      */
     public function isChangeTrackingDeferredExplicit()
     {
-        return $this->changeTrackingPolicy == self::CHANGETRACKING_DEFERRED_EXPLICIT;
+        return $this->changeTrackingPolicy === self::CHANGETRACKING_DEFERRED_EXPLICIT;
     }
 
     /**
      * Whether the change tracking policy of this class is "deferred implicit".
      *
-     * @return boolean
+     * @return bool
      */
     public function isChangeTrackingDeferredImplicit()
     {
-        return $this->changeTrackingPolicy == self::CHANGETRACKING_DEFERRED_IMPLICIT;
+        return $this->changeTrackingPolicy === self::CHANGETRACKING_DEFERRED_IMPLICIT;
     }
 
     /**
      * Whether the change tracking policy of this class is "notify".
      *
-     * @return boolean
+     * @return bool
      */
     public function isChangeTrackingNotify()
     {
-        return $this->changeTrackingPolicy == self::CHANGETRACKING_NOTIFY;
+        return $this->changeTrackingPolicy === self::CHANGETRACKING_NOTIFY;
     }
 
     /**
@@ -1082,7 +1107,7 @@ public function getCollection()
     public function setCollection($name)
     {
         if (is_array($name)) {
-            if ( ! isset($name['name'])) {
+            if (! isset($name['name'])) {
                 throw new \InvalidArgumentException('A name key is required when passing an array to setCollection()');
             }
             $this->collectionCapped = $name['capped'] ?? false;
@@ -1097,7 +1122,7 @@ public function setCollection($name)
     /**
      * Get whether or not the documents collection is capped.
      *
-     * @return boolean
+     * @return bool
      */
     public function getCollectionCapped()
     {
@@ -1107,7 +1132,7 @@ public function getCollectionCapped()
     /**
      * Set whether or not the documents collection is capped.
      *
-     * @param boolean $bool
+     * @param bool $bool
      */
     public function setCollectionCapped($bool)
     {
@@ -1117,7 +1142,7 @@ public function setCollectionCapped($bool)
     /**
      * Get the collection size
      *
-     * @return integer
+     * @return int
      */
     public function getCollectionSize()
     {
@@ -1127,7 +1152,7 @@ public function getCollectionSize()
     /**
      * Set the collection size.
      *
-     * @param integer $size
+     * @param int $size
      */
     public function setCollectionSize($size)
     {
@@ -1137,7 +1162,7 @@ public function setCollectionSize($size)
     /**
      * Get the collection max.
      *
-     * @return integer
+     * @return int
      */
     public function getCollectionMax()
     {
@@ -1147,7 +1172,7 @@ public function getCollectionMax()
     /**
      * Set the collection max.
      *
-     * @param integer $max
+     * @param int $max
      */
     public function setCollectionMax($max)
     {
@@ -1157,7 +1182,7 @@ public function setCollectionMax($max)
     /**
      * Returns TRUE if this Document is mapped to a collection FALSE otherwise.
      *
-     * @return boolean
+     * @return bool
      */
     public function isMappedToCollection()
     {
@@ -1167,7 +1192,7 @@ public function isMappedToCollection()
     /**
      * Validates the storage strategy of a mapping for consistency
      * @param array $mapping
-     * @throws \Doctrine\ODM\MongoDB\Mapping\MappingException
+     * @throws MappingException
      */
     private function applyStorageStrategy(array &$mapping)
     {
@@ -1176,13 +1201,13 @@ private function applyStorageStrategy(array &$mapping)
         }
 
         switch (true) {
-            case $mapping['type'] == 'int':
-            case $mapping['type'] == 'float':
+            case $mapping['type'] === 'int':
+            case $mapping['type'] === 'float':
                 $defaultStrategy = self::STORAGE_STRATEGY_SET;
                 $allowedStrategies = [self::STORAGE_STRATEGY_SET, self::STORAGE_STRATEGY_INCREMENT];
                 break;
 
-            case $mapping['type'] == 'many':
+            case $mapping['type'] === 'many':
                 $defaultStrategy = CollectionHelper::DEFAULT_STRATEGY;
                 $allowedStrategies = [
                     self::STORAGE_STRATEGY_PUSH_ALL,
@@ -1284,7 +1309,6 @@ public function addInheritedFieldMapping(array $fieldMapping)
      *
      * @param array $mapping
      *
-     * @return void
      *
      * @throws MappingException
      */
@@ -1297,7 +1321,7 @@ public function addInheritedAssociationMapping(array $mapping/*, $owningClassNam
      * Checks whether the class has a mapped association with the given field name.
      *
      * @param string $fieldName
-     * @return boolean
+     * @return bool
      */
     public function hasReference($fieldName)
     {
@@ -1308,7 +1332,7 @@ public function hasReference($fieldName)
      * Checks whether the class has a mapped embed with the given field name.
      *
      * @param string $fieldName
-     * @return boolean
+     * @return bool
      */
     public function hasEmbed($fieldName)
     {
@@ -1352,7 +1376,7 @@ public function isCollectionValuedAssociation($fieldName)
      * and if yes, checks whether it is a single-valued association (to-one).
      *
      * @param string $fieldName
-     * @return boolean TRUE if the association exists and is single-valued, FALSE otherwise.
+     * @return bool TRUE if the association exists and is single-valued, FALSE otherwise.
      */
     public function isSingleValuedReference($fieldName)
     {
@@ -1365,7 +1389,7 @@ public function isSingleValuedReference($fieldName)
      * and if yes, checks whether it is a collection-valued association (to-many).
      *
      * @param string $fieldName
-     * @return boolean TRUE if the association exists and is collection-valued, FALSE otherwise.
+     * @return bool TRUE if the association exists and is collection-valued, FALSE otherwise.
      */
     public function isCollectionValuedReference($fieldName)
     {
@@ -1378,7 +1402,7 @@ public function isCollectionValuedReference($fieldName)
      * and if yes, checks whether it is a single-valued association (to-one).
      *
      * @param string $fieldName
-     * @return boolean TRUE if the association exists and is single-valued, FALSE otherwise.
+     * @return bool TRUE if the association exists and is single-valued, FALSE otherwise.
      */
     public function isSingleValuedEmbed($fieldName)
     {
@@ -1391,7 +1415,7 @@ public function isSingleValuedEmbed($fieldName)
      * and if yes, checks whether it is a collection-valued association (to-many).
      *
      * @param string $fieldName
-     * @return boolean TRUE if the association exists and is collection-valued, FALSE otherwise.
+     * @return bool TRUE if the association exists and is collection-valued, FALSE otherwise.
      */
     public function isCollectionValuedEmbed($fieldName)
     {
@@ -1402,7 +1426,7 @@ public function isCollectionValuedEmbed($fieldName)
     /**
      * Sets the ID generator used to generate IDs for instances of this class.
      *
-     * @param \Doctrine\ODM\MongoDB\Id\AbstractIdGenerator $generator
+     * @param AbstractIdGenerator $generator
      */
     public function setIdGenerator($generator)
     {
@@ -1439,7 +1463,7 @@ public function getDatabaseIdentifierValue($id)
      * The value will be converted to a PHP type before being set.
      *
      * @param object $document
-     * @param mixed $id
+     * @param mixed  $id
      */
     public function setIdentifierValue($document, $id)
     {
@@ -1467,7 +1491,7 @@ public function getIdentifierValue($document)
      */
     public function getIdentifierValues($object)
     {
-        return array($this->identifier => $this->getIdentifierValue($object));
+        return [$this->identifier => $this->getIdentifierValue($object)];
     }
 
     /**
@@ -1475,7 +1499,7 @@ public function getIdentifierValues($object)
      *
      * @param object $document
      *
-     * @return \MongoDB\BSON\ObjectId $id The ObjectId
+     * @return ObjectId $id The ObjectId
      */
     public function getIdentifierObject($document)
     {
@@ -1487,7 +1511,7 @@ public function getIdentifierObject($document)
      *
      * @param object $document
      * @param string $field
-     * @param mixed $value
+     * @param mixed  $value
      */
     public function setFieldValue($document, $field, $value)
     {
@@ -1520,7 +1544,7 @@ public function getFieldValue($document, $field)
     /**
      * Gets the mapping of a field.
      *
-     * @param string $fieldName  The field name.
+     * @param string $fieldName The field name.
      *
      * @return array  The field mapping.
      *
@@ -1528,7 +1552,7 @@ public function getFieldValue($document, $field)
      */
     public function getFieldMapping($fieldName)
     {
-        if ( ! isset($this->fieldMappings[$fieldName])) {
+        if (! isset($this->fieldMappings[$fieldName])) {
             throw MappingException::mappingNotFound($this->name, $fieldName);
         }
         return $this->fieldMappings[$fieldName];
@@ -1543,7 +1567,9 @@ public function getEmbeddedFieldsMappings()
     {
         return array_filter(
             $this->associationMappings,
-            function($assoc) { return ! empty($assoc['embedded']); }
+            function ($assoc) {
+                return ! empty($assoc['embedded']);
+            }
         );
     }
 
@@ -1559,7 +1585,7 @@ function($assoc) { return ! empty($assoc['embedded']); }
     public function getFieldMappingByDbFieldName($dbFieldName)
     {
         foreach ($this->fieldMappings as $mapping) {
-            if ($mapping['name'] == $dbFieldName) {
+            if ($mapping['name'] === $dbFieldName) {
                 return $mapping;
             }
         }
@@ -1570,15 +1596,15 @@ public function getFieldMappingByDbFieldName($dbFieldName)
     /**
      * Check if the field is not null.
      *
-     * @param string $fieldName  The field name
+     * @param string $fieldName The field name
      *
-     * @return boolean  TRUE if the field is not null, FALSE otherwise.
+     * @return bool  TRUE if the field is not null, FALSE otherwise.
      */
     public function isNullable($fieldName)
     {
         $mapping = $this->getFieldMapping($fieldName);
         if ($mapping !== false) {
-            return isset($mapping['nullable']) && $mapping['nullable'] == true;
+            return isset($mapping['nullable']) && $mapping['nullable'] === true;
         }
         return false;
     }
@@ -1586,7 +1612,7 @@ public function isNullable($fieldName)
     /**
      * Checks whether the document has a discriminator field and value configured.
      *
-     * @return boolean
+     * @return bool
      */
     public function hasDiscriminator()
     {
@@ -1614,31 +1640,31 @@ public function setIdGeneratorOptions($generatorOptions)
     }
 
     /**
-     * @return boolean
+     * @return bool
      */
     public function isInheritanceTypeNone()
     {
-        return $this->inheritanceType == self::INHERITANCE_TYPE_NONE;
+        return $this->inheritanceType === self::INHERITANCE_TYPE_NONE;
     }
 
     /**
      * Checks whether the mapped class uses the SINGLE_COLLECTION inheritance mapping strategy.
      *
-     * @return boolean
+     * @return bool
      */
     public function isInheritanceTypeSingleCollection()
     {
-        return $this->inheritanceType == self::INHERITANCE_TYPE_SINGLE_COLLECTION;
+        return $this->inheritanceType === self::INHERITANCE_TYPE_SINGLE_COLLECTION;
     }
 
     /**
      * Checks whether the mapped class uses the COLLECTION_PER_CLASS inheritance mapping strategy.
      *
-     * @return boolean
+     * @return bool
      */
     public function isInheritanceTypeCollectionPerClass()
     {
-        return $this->inheritanceType == self::INHERITANCE_TYPE_COLLECTION_PER_CLASS;
+        return $this->inheritanceType === self::INHERITANCE_TYPE_COLLECTION_PER_CLASS;
     }
 
     /**
@@ -1676,48 +1702,48 @@ public function setParentClasses(array $classNames)
     /**
      * Checks whether the class will generate a new \MongoDB\BSON\ObjectId instance for us.
      *
-     * @return boolean TRUE if the class uses the AUTO generator, FALSE otherwise.
+     * @return bool TRUE if the class uses the AUTO generator, FALSE otherwise.
      */
     public function isIdGeneratorAuto()
     {
-        return $this->generatorType == self::GENERATOR_TYPE_AUTO;
+        return $this->generatorType === self::GENERATOR_TYPE_AUTO;
     }
 
     /**
      * Checks whether the class will use a collection to generate incremented identifiers.
      *
-     * @return boolean TRUE if the class uses the INCREMENT generator, FALSE otherwise.
+     * @return bool TRUE if the class uses the INCREMENT generator, FALSE otherwise.
      */
     public function isIdGeneratorIncrement()
     {
-        return $this->generatorType == self::GENERATOR_TYPE_INCREMENT;
+        return $this->generatorType === self::GENERATOR_TYPE_INCREMENT;
     }
 
     /**
      * Checks whether the class will generate a uuid id.
      *
-     * @return boolean TRUE if the class uses the UUID generator, FALSE otherwise.
+     * @return bool TRUE if the class uses the UUID generator, FALSE otherwise.
      */
     public function isIdGeneratorUuid()
     {
-        return $this->generatorType == self::GENERATOR_TYPE_UUID;
+        return $this->generatorType === self::GENERATOR_TYPE_UUID;
     }
 
     /**
      * Checks whether the class uses no id generator.
      *
-     * @return boolean TRUE if the class does not use any id generator, FALSE otherwise.
+     * @return bool TRUE if the class does not use any id generator, FALSE otherwise.
      */
     public function isIdGeneratorNone()
     {
-        return $this->generatorType == self::GENERATOR_TYPE_NONE;
+        return $this->generatorType === self::GENERATOR_TYPE_NONE;
     }
 
     /**
      * Sets the version field mapping used for versioning. Sets the default
      * value to use depending on the column type.
      *
-     * @param array $mapping   The version field mapping array
+     * @param array $mapping The version field mapping array
      *
      * @throws LockException
      */
@@ -1734,7 +1760,7 @@ public function setVersionMapping(array &$mapping)
     /**
      * Sets whether this class is to be versioned for optimistic locking.
      *
-     * @param boolean $bool
+     * @param bool $bool
      */
     public function setVersioned($bool)
     {
@@ -1756,9 +1782,9 @@ public function setVersionField($versionField)
      * Sets the version field mapping used for versioning. Sets the default
      * value to use depending on the column type.
      *
-     * @param array $mapping   The version field mapping array
+     * @param array $mapping The version field mapping array
      *
-     * @throws \Doctrine\ODM\MongoDB\LockException
+     * @throws LockException
      */
     public function setLockMapping(array &$mapping)
     {
@@ -1773,7 +1799,7 @@ public function setLockMapping(array &$mapping)
     /**
      * Sets whether this class is to allow pessimistic locking.
      *
-     * @param boolean $bool
+     * @param bool $bool
      */
     public function setLockable($bool)
     {
@@ -1829,7 +1855,7 @@ public function getTypeOfField($fieldName)
      */
     public function getAssociationTargetClass($assocName)
     {
-        if ( ! isset($this->associationMappings[$assocName])) {
+        if (! isset($this->associationMappings[$assocName])) {
             throw new InvalidArgumentException("Association name expected, '" . $assocName . "' is not an association.");
         }
 
@@ -1843,11 +1869,11 @@ public function getAssociationTargetClass($assocName)
      */
     public function getAssociationCollectionClass($assocName)
     {
-        if ( ! isset($this->associationMappings[$assocName])) {
+        if (! isset($this->associationMappings[$assocName])) {
             throw new InvalidArgumentException("Association name expected, '" . $assocName . "' is not an association.");
         }
 
-        if ( ! array_key_exists('collectionClass', $this->associationMappings[$assocName])) {
+        if (! array_key_exists('collectionClass', $this->associationMappings[$assocName])) {
             throw new InvalidArgumentException("collectionClass can only be applied to 'embedMany' and 'referenceMany' associations.");
         }
 
@@ -1881,22 +1907,19 @@ public function getAssociationMappedByTargetField($fieldName)
      */
     public function mapField(array $mapping)
     {
-        if ( ! isset($mapping['fieldName']) && isset($mapping['name'])) {
+        if (! isset($mapping['fieldName']) && isset($mapping['name'])) {
             $mapping['fieldName'] = $mapping['name'];
         }
-        if ( ! isset($mapping['fieldName'])) {
+        if (! isset($mapping['fieldName'])) {
             throw MappingException::missingFieldName($this->name);
         }
-        if ( ! isset($mapping['name'])) {
+        if (! isset($mapping['name'])) {
             $mapping['name'] = $mapping['fieldName'];
         }
         if ($this->identifier === $mapping['name'] && empty($mapping['id'])) {
             throw MappingException::mustNotChangeIdentifierFieldsType($this->name, $mapping['name']);
         }
-        if (isset($this->fieldMappings[$mapping['fieldName']])) {
-            //throw MappingException::duplicateFieldMapping($this->name, $mapping['fieldName']);
-        }
-        if ($this->discriminatorField !== null && $this->discriminatorField == $mapping['name']) {
+        if ($this->discriminatorField !== null && $this->discriminatorField === $mapping['name']) {
             throw MappingException::discriminatorFieldConflict($this->name, $this->discriminatorField);
         }
         if (isset($mapping['targetDocument']) && strpos($mapping['targetDocument'], '\\') === false && strlen($this->namespace)) {
@@ -1908,9 +1931,9 @@ public function mapField(array $mapping)
             }
             $mapping['collectionClass'] = ltrim($mapping['collectionClass'], '\\');
         }
-        if ( ! empty($mapping['collectionClass'])) {
+        if (! empty($mapping['collectionClass'])) {
             $rColl = new \ReflectionClass($mapping['collectionClass']);
-            if ( ! $rColl->implementsInterface('Doctrine\\Common\\Collections\\Collection')) {
+            if (! $rColl->implementsInterface('Doctrine\\Common\\Collections\\Collection')) {
                 throw MappingException::collectionClassDoesNotImplementCommonInterface($this->name, $mapping['fieldName'], $mapping['collectionClass']);
             }
         }
@@ -1927,10 +1950,10 @@ public function mapField(array $mapping)
             throw MappingException::cascadeOnEmbeddedNotAllowed($this->name, $mapping['fieldName']);
         }
 
-        $cascades = isset($mapping['cascade']) ? array_map('strtolower', (array) $mapping['cascade']) : array();
+        $cascades = isset($mapping['cascade']) ? array_map('strtolower', (array) $mapping['cascade']) : [];
 
         if (in_array('all', $cascades) || isset($mapping['embedded'])) {
-            $cascades = array('remove', 'persist', 'refresh', 'merge', 'detach');
+            $cascades = ['remove', 'persist', 'refresh', 'merge', 'detach'];
         }
 
         if (isset($mapping['embedded'])) {
@@ -1949,15 +1972,15 @@ public function mapField(array $mapping)
             $mapping['name'] = '_id';
             $this->identifier = $mapping['fieldName'];
             if (isset($mapping['strategy'])) {
-                $this->generatorType = constant(ClassMetadata::class . '::GENERATOR_TYPE_' . strtoupper($mapping['strategy']));
+                $this->generatorType = constant(self::class . '::GENERATOR_TYPE_' . strtoupper($mapping['strategy']));
             }
-            $this->generatorOptions = $mapping['options'] ?? array();
+            $this->generatorOptions = $mapping['options'] ?? [];
             switch ($this->generatorType) {
                 case self::GENERATOR_TYPE_AUTO:
                     $mapping['type'] = 'id';
                     break;
                 default:
-                    if ( ! empty($this->generatorOptions['type'])) {
+                    if (! empty($this->generatorOptions['type'])) {
                         $mapping['type'] = $this->generatorOptions['type'];
                     } elseif (empty($mapping['type'])) {
                         $mapping['type'] = $this->generatorType === self::GENERATOR_TYPE_INCREMENT ? 'int_id' : 'custom_id';
@@ -1966,13 +1989,13 @@ public function mapField(array $mapping)
             unset($this->generatorOptions['type']);
         }
 
-        if ( ! isset($mapping['nullable'])) {
+        if (! isset($mapping['nullable'])) {
             $mapping['nullable'] = false;
         }
 
         if (isset($mapping['reference'])
             && isset($mapping['storeAs'])
-            && $mapping['storeAs'] === ClassMetadata::REFERENCE_STORE_AS_ID
+            && $mapping['storeAs'] === self::REFERENCE_STORE_AS_ID
             && ! isset($mapping['targetDocument'])
         ) {
             throw MappingException::simpleReferenceRequiresTargetDocument($this->name, $mapping['fieldName']);
@@ -2032,12 +2055,12 @@ public function mapField(array $mapping)
                 $mapping['isInverseSide'] = true;
                 $mapping['isOwningSide'] = false;
             }
-            if (!isset($mapping['orphanRemoval'])) {
+            if (! isset($mapping['orphanRemoval'])) {
                 $mapping['orphanRemoval'] = false;
             }
         }
 
-        if (!empty($mapping['prime']) && ($mapping['association'] !== self::REFERENCE_MANY || !$mapping['isInverseSide'])) {
+        if (! empty($mapping['prime']) && ($mapping['association'] !== self::REFERENCE_MANY || ! $mapping['isInverseSide'])) {
             throw MappingException::referencePrimersOnlySupportedForInverseReferenceMany($this->name, $mapping['fieldName']);
         }
 
@@ -2071,7 +2094,7 @@ public function mapField(array $mapping)
     public function __sleep()
     {
         // This metadata is always serialized/cached.
-        $serialized = array(
+        $serialized = [
             'fieldMappings',
             'associationMappings',
             'identifier',
@@ -2088,10 +2111,10 @@ public function __sleep()
             'idGenerator',
             'indexes',
             'shardKey',
-        );
+        ];
 
         // The rest of the metadata is only serialized if necessary.
-        if ($this->changeTrackingPolicy != self::CHANGETRACKING_DEFERRED_IMPLICIT) {
+        if ($this->changeTrackingPolicy !== self::CHANGETRACKING_DEFERRED_IMPLICIT) {
             $serialized[] = 'changeTrackingPolicy';
         }
 
@@ -2099,7 +2122,7 @@ public function __sleep()
             $serialized[] = 'customRepositoryClassName';
         }
 
-        if ($this->inheritanceType != self::INHERITANCE_TYPE_NONE || $this->discriminatorField !== null) {
+        if ($this->inheritanceType !== self::INHERITANCE_TYPE_NONE || $this->discriminatorField !== null) {
             $serialized[] = 'inheritanceType';
             $serialized[] = 'discriminatorField';
             $serialized[] = 'discriminatorValue';
@@ -2146,7 +2169,6 @@ public function __sleep()
     /**
      * Restores some state that can not be serialized/unserialized.
      *
-     * @return void
      */
     public function __wakeup()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadataFactory.php
index 04537a6514..6d28497ef3 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadataFactory.php
@@ -1,9 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping;
 
+use Doctrine\Common\EventManager;
 use Doctrine\Common\Persistence\Mapping\AbstractClassMetadataFactory;
 use Doctrine\Common\Persistence\Mapping\ClassMetadata as ClassMetadataInterface;
+use Doctrine\Common\Persistence\Mapping\Driver\MappingDriver;
 use Doctrine\Common\Persistence\Mapping\ReflectionService;
 use Doctrine\ODM\MongoDB\Configuration;
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -14,17 +18,20 @@
 use Doctrine\ODM\MongoDB\Id\AutoGenerator;
 use Doctrine\ODM\MongoDB\Id\IncrementGenerator;
 use Doctrine\ODM\MongoDB\Id\UuidGenerator;
+use function get_class;
+use function get_class_methods;
+use function in_array;
+use function ucfirst;
 
 /**
  * The ClassMetadataFactory is used to create ClassMetadata objects that contain all the
  * metadata mapping informations of a class which describes how a class should be mapped
  * to a document database.
  *
- * @since       1.0
  */
 class ClassMetadataFactory extends AbstractClassMetadataFactory
 {
-    protected $cacheSalt = "\$MONGODBODMCLASSMETADATA";
+    protected $cacheSalt = '$MONGODBODMCLASSMETADATA';
 
     /** @var DocumentManager The DocumentManager instance */
     private $dm;
@@ -32,10 +39,10 @@ class ClassMetadataFactory extends AbstractClassMetadataFactory
     /** @var Configuration The Configuration instance */
     private $config;
 
-    /** @var \Doctrine\Common\Persistence\Mapping\Driver\MappingDriver The used metadata driver. */
+    /** @var MappingDriver The used metadata driver. */
     private $driver;
 
-    /** @var \Doctrine\Common\EventManager The event manager instance */
+    /** @var EventManager The event manager instance */
     private $evm;
 
     /**
@@ -51,7 +58,6 @@ public function setDocumentManager(DocumentManager $dm)
     /**
      * Sets the Configuration instance
      *
-     * @param Configuration $config
      */
     public function setConfiguration(Configuration $config)
     {
@@ -110,7 +116,7 @@ protected function isEntity(ClassMetadataInterface $class)
     /**
      * {@inheritDoc}
      */
-    protected function doLoadMetadata($class, $parent, $rootEntityFound, array $nonSuperclassParents = array())
+    protected function doLoadMetadata($class, $parent, $rootEntityFound, array $nonSuperclassParents = [])
     {
         /** @var $class ClassMetadata */
         /** @var $parent ClassMetadata */
@@ -181,7 +187,7 @@ protected function doLoadMetadata($class, $parent, $rootEntityFound, array $nonS
      */
     protected function validateIdentifier($class)
     {
-        if ( ! $class->identifier && ! $class->isMappedSuperclass && ! $class->isEmbeddedDocument && ! $class->isQueryResultDocument) {
+        if (! $class->identifier && ! $class->isMappedSuperclass && ! $class->isEmbeddedDocument && ! $class->isQueryResultDocument) {
             throw MappingException::identifierRequired($class->name);
         }
     }
@@ -190,7 +196,7 @@ protected function validateIdentifier($class)
      * Creates a new ClassMetadata instance for the given class name.
      *
      * @param string $className
-     * @return \Doctrine\ODM\MongoDB\Mapping\ClassMetadata
+     * @return ClassMetadata
      */
     protected function newClassMetadataInstance($className)
     {
@@ -240,16 +246,16 @@ private function completeIdGeneratorMapping(ClassMetadata $class)
                     throw MappingException::missingIdGeneratorClass($class->name);
                 }
 
-                $customGenerator = new $idGenOptions['class'];
+                $customGenerator = new $idGenOptions['class']();
                 unset($idGenOptions['class']);
-                if ( ! $customGenerator instanceof AbstractIdGenerator) {
+                if (! $customGenerator instanceof AbstractIdGenerator) {
                     throw MappingException::classIsNotAValidGenerator(get_class($customGenerator));
                 }
 
                 $methods = get_class_methods($customGenerator);
                 foreach ($idGenOptions as $name => $value) {
                     $method = 'set' . ucfirst($name);
-                    if ( ! in_array($method, $methods)) {
+                    if (! in_array($method, $methods)) {
                         throw MappingException::missingGeneratorSetter(get_class($customGenerator), $name);
                     }
 
@@ -267,16 +273,14 @@ private function completeIdGeneratorMapping(ClassMetadata $class)
     /**
      * Adds inherited fields to the subclass mapping.
      *
-     * @param ClassMetadata $subClass
-     * @param ClassMetadata $parentClass
      */
     private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $parentClass)
     {
         foreach ($parentClass->fieldMappings as $fieldName => $mapping) {
-            if ( ! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
+            if (! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
                 $mapping['inherited'] = $parentClass->name;
             }
-            if ( ! isset($mapping['declared'])) {
+            if (! isset($mapping['declared'])) {
                 $mapping['declared'] = $parentClass->name;
             }
             $subClass->addInheritedFieldMapping($mapping);
@@ -290,10 +294,7 @@ private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $pare
     /**
      * Adds inherited association mappings to the subclass mapping.
      *
-     * @param \Doctrine\ODM\MongoDB\Mapping\ClassMetadata $subClass
-     * @param \Doctrine\ODM\MongoDB\Mapping\ClassMetadata $parentClass
      *
-     * @return void
      *
      * @throws MappingException
      */
@@ -304,10 +305,10 @@ private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $p
                 $mapping['sourceDocument'] = $subClass->name;
             }
 
-            if ( ! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
+            if (! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
                 $mapping['inherited'] = $parentClass->name;
             }
-            if ( ! isset($mapping['declared'])) {
+            if (! isset($mapping['declared'])) {
                 $mapping['declared'] = $parentClass->name;
             }
             $subClass->addInheritedAssociationMapping($mapping);
@@ -317,8 +318,6 @@ private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $p
     /**
      * Adds inherited indexes to the subclass mapping.
      *
-     * @param ClassMetadata $subClass
-     * @param ClassMetadata $parentClass
      */
     private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $parentClass)
     {
@@ -330,8 +329,6 @@ private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $par
     /**
      * Adds inherited shard key to the subclass mapping.
      *
-     * @param ClassMetadata $subClass
-     * @param ClassMetadata $parentClass
      */
     private function setInheritedShardKey(ClassMetadata $subClass, ClassMetadata $parentClass)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/AnnotationDriver.php b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/AnnotationDriver.php
index aac40f8924..28916671d6 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/AnnotationDriver.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/AnnotationDriver.php
@@ -1,41 +1,50 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Driver;
 
 use Doctrine\Common\Annotations\AnnotationReader;
-use Doctrine\Common\Annotations\AnnotationRegistry;
 use Doctrine\Common\Annotations\Reader;
 use Doctrine\Common\Persistence\Mapping\Driver\AnnotationDriver as AbstractAnnotationDriver;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
+use const E_USER_DEPRECATED;
+use function array_merge;
+use function array_replace;
+use function constant;
+use function get_class;
+use function is_array;
+use function ksort;
+use function reset;
+use function trigger_error;
 
 /**
  * The AnnotationDriver reads the mapping metadata from docblock annotations.
  *
- * @since       1.0
  */
 class AnnotationDriver extends AbstractAnnotationDriver
 {
-    protected $entityAnnotationClasses = array(
+    protected $entityAnnotationClasses = [
         ODM\Document::class            => 1,
         ODM\MappedSuperclass::class    => 2,
         ODM\EmbeddedDocument::class    => 3,
         ODM\QueryResultDocument::class => 4,
-    );
+    ];
 
     /**
      * {@inheritdoc}
      */
     public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Mapping\ClassMetadata $class)
     {
-        /** @var $class ClassMetadata */
+        /** @var ClassMetadata $class */
         $reflClass = $class->getReflectionClass();
 
         $classAnnotations = $this->reader->getClassAnnotations($reflClass);
 
-        $documentAnnots = array();
+        $documentAnnots = [];
         foreach ($classAnnotations as $annot) {
             $classAnnotations[get_class($annot)] = $annot;
 
@@ -51,11 +60,11 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
                 $this->addIndex($class, $annot);
             }
             if ($annot instanceof ODM\Indexes) {
-                foreach (is_array($annot->value) ? $annot->value : array($annot->value) as $index) {
+                foreach (is_array($annot->value) ? $annot->value : [$annot->value] as $index) {
                     $this->addIndex($class, $index);
                 }
             } elseif ($annot instanceof ODM\InheritanceType) {
-                $class->setInheritanceType(constant(ClassMetadata::class . '::INHERITANCE_TYPE_'.$annot->value));
+                $class->setInheritanceType(constant(ClassMetadata::class . '::INHERITANCE_TYPE_' . $annot->value));
             } elseif ($annot instanceof ODM\DiscriminatorField) {
                 $class->setDiscriminatorField($annot->value);
             } elseif ($annot instanceof ODM\DiscriminatorMap) {
@@ -63,16 +72,15 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
             } elseif ($annot instanceof ODM\DiscriminatorValue) {
                 $class->setDiscriminatorValue($annot->value);
             } elseif ($annot instanceof ODM\ChangeTrackingPolicy) {
-                $class->setChangeTrackingPolicy(constant(ClassMetadata::class . '::CHANGETRACKING_'.$annot->value));
+                $class->setChangeTrackingPolicy(constant(ClassMetadata::class . '::CHANGETRACKING_' . $annot->value));
             } elseif ($annot instanceof ODM\DefaultDiscriminatorValue) {
                 $class->setDefaultDiscriminatorValue($annot->value);
             } elseif ($annot instanceof ODM\ReadPreference) {
                 $class->setReadPreference($annot->value, $annot->tags);
             }
-
         }
 
-        if ( ! $documentAnnots) {
+        if (! $documentAnnots) {
             throw MappingException::classIsNotAValidDocument($className);
         }
 
@@ -115,8 +123,8 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
                 continue;
             }
 
-            $indexes = array();
-            $mapping = array('fieldName' => $property->getName());
+            $indexes = [];
+            $mapping = ['fieldName' => $property->getName()];
             $fieldAnnot = null;
 
             foreach ($this->reader->getPropertyAnnotations($property) as $annot) {
@@ -130,7 +138,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
                     $indexes[] = $annot;
                 }
                 if ($annot instanceof ODM\Indexes) {
-                    foreach (is_array($annot->value) ? $annot->value : array($annot->value) as $index) {
+                    foreach (is_array($annot->value) ? $annot->value : [$annot->value] as $index) {
                         $indexes[] = $index;
                     }
                 } elseif ($annot instanceof ODM\AlsoLoad) {
@@ -150,7 +158,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
             if ($indexes) {
                 foreach ($indexes as $index) {
                     $name = $mapping['name'] ?? $mapping['fieldName'];
-                    $keys = array($name => $index->order ?: 'asc');
+                    $keys = [$name => $index->order ?: 'asc'];
                     $this->addIndex($class, $index, $keys);
                 }
             }
@@ -175,7 +183,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
                     $class->registerAlsoLoadMethod($method->getName(), $annot->value);
                 }
 
-                if ( ! isset($classAnnotations[ODM\HasLifecycleCallbacks::class])) {
+                if (! isset($classAnnotations[ODM\HasLifecycleCallbacks::class])) {
                     continue;
                 }
 
@@ -202,11 +210,11 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
         }
     }
 
-    private function addIndex(ClassMetadata $class, $index, array $keys = array())
+    private function addIndex(ClassMetadata $class, $index, array $keys = [])
     {
         $keys = array_merge($keys, $index->keys);
-        $options = array();
-        $allowed = array('name', 'dropDups', 'background', 'unique', 'sparse', 'expireAfterSeconds');
+        $options = [];
+        $allowed = ['name', 'dropDups', 'background', 'unique', 'sparse', 'expireAfterSeconds'];
         foreach ($allowed as $name) {
             if (isset($index->$name)) {
                 $options[$name] = $index->$name;
@@ -220,15 +228,13 @@ private function addIndex(ClassMetadata $class, $index, array $keys = array())
     }
 
     /**
-     * @param ClassMetadata $class
-     * @param ODM\ShardKey      $shardKey
      *
      * @throws MappingException
      */
     private function setShardKey(ClassMetadata $class, ODM\ShardKey $shardKey)
     {
-        $options = array();
-        $allowed = array('unique', 'numInitialChunks');
+        $options = [];
+        $allowed = ['unique', 'numInitialChunks'];
         foreach ($allowed as $name) {
             if (isset($shardKey->$name)) {
                 $options[$name] = $shardKey->$name;
@@ -242,10 +248,9 @@ private function setShardKey(ClassMetadata $class, ODM\ShardKey $shardKey)
      * Factory method for the Annotation Driver
      *
      * @param array|string $paths
-     * @param Reader $reader
      * @return AnnotationDriver
      */
-    public static function create($paths = array(), Reader $reader = null)
+    public static function create($paths = [], ?Reader $reader = null)
     {
         if ($reader === null) {
             $reader = new AnnotationReader();
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/SimplifiedXmlDriver.php b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/SimplifiedXmlDriver.php
index 3a9f8ead11..e638a0be16 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/SimplifiedXmlDriver.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/SimplifiedXmlDriver.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Driver;
 
 use Doctrine\Common\Persistence\Mapping\Driver\SymfonyFileLocator;
@@ -7,11 +9,10 @@
 /**
  * XmlDriver that additionally looks for mapping information in a global file.
  *
- * @license MIT
  */
 class SimplifiedXmlDriver extends XmlDriver
 {
-    const DEFAULT_FILE_EXTENSION = '.mongodb-odm.xml';
+    public const DEFAULT_FILE_EXTENSION = '.mongodb-odm.xml';
 
     /**
      * {@inheritDoc}
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/XmlDriver.php b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/XmlDriver.php
index 411d083b61..f44109b5aa 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/Driver/XmlDriver.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/Driver/XmlDriver.php
@@ -1,19 +1,33 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping\Driver;
 
 use Doctrine\Common\Persistence\Mapping\Driver\FileDriver;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use function array_keys;
+use function constant;
+use function count;
+use function current;
+use function explode;
+use function in_array;
+use function is_numeric;
+use function iterator_to_array;
+use function next;
+use function preg_match;
+use function simplexml_load_file;
+use function strtoupper;
+use function trim;
 
 /**
  * XmlDriver is a metadata driver that enables mapping through XML files.
  *
- * @since       1.0
  */
 class XmlDriver extends FileDriver
 {
-    const DEFAULT_FILE_EXTENSION = '.dcm.xml';
+    public const DEFAULT_FILE_EXTENSION = '.dcm.xml';
 
     /**
      * {@inheritDoc}
@@ -31,22 +45,22 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
         /* @var $class ClassMetadata */
         /* @var $xmlRoot \SimpleXMLElement */
         $xmlRoot = $this->getElement($className);
-        if ( ! $xmlRoot) {
+        if (! $xmlRoot) {
             return;
         }
 
-        if ($xmlRoot->getName() == 'document') {
+        if ($xmlRoot->getName() === 'document') {
             if (isset($xmlRoot['repository-class'])) {
                 $class->setCustomRepositoryClass((string) $xmlRoot['repository-class']);
             }
-        } elseif ($xmlRoot->getName() == 'mapped-superclass') {
+        } elseif ($xmlRoot->getName() === 'mapped-superclass') {
             $class->setCustomRepositoryClass(
                 isset($xmlRoot['repository-class']) ? (string) $xmlRoot['repository-class'] : null
             );
             $class->isMappedSuperclass = true;
-        } elseif ($xmlRoot->getName() == 'embedded-document') {
+        } elseif ($xmlRoot->getName() === 'embedded-document') {
             $class->isEmbeddedDocument = true;
-        } elseif ($xmlRoot->getName() == 'query-result-document') {
+        } elseif ($xmlRoot->getName() === 'query-result-document') {
             $class->isQueryResultDocument = true;
         }
         if (isset($xmlRoot['db'])) {
@@ -54,7 +68,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
         }
         if (isset($xmlRoot['collection'])) {
             if (isset($xmlRoot['capped-collection'])) {
-                $config = array('name' => (string) $xmlRoot['collection']);
+                $config = ['name' => (string) $xmlRoot['collection']];
                 $config['capped'] = (bool) $xmlRoot['capped-collection'];
                 if (isset($xmlRoot['capped-collection-max'])) {
                     $config['max'] = (int) $xmlRoot['capped-collection-max'];
@@ -87,7 +101,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
             );
         }
         if (isset($xmlRoot->{'discriminator-map'})) {
-            $map = array();
+            $map = [];
             foreach ($xmlRoot->{'discriminator-map'}->{'discriminator-mapping'} as $discrMapElement) {
                 $map[(string) $discrMapElement['value']] = (string) $discrMapElement['class'];
             }
@@ -104,7 +118,7 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
         if (isset($xmlRoot->{'shard-key'})) {
             $this->setShardKey($class, $xmlRoot->{'shard-key'}[0]);
         }
-        if (isset($xmlRoot['read-only']) && 'true' === (string) $xmlRoot['read-only']) {
+        if (isset($xmlRoot['read-only']) && (string) $xmlRoot['read-only'] === 'true') {
             $class->markReadOnly();
         }
         if (isset($xmlRoot->{'read-preference'})) {
@@ -112,17 +126,17 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
         }
         if (isset($xmlRoot->field)) {
             foreach ($xmlRoot->field as $field) {
-                $mapping = array();
+                $mapping = [];
                 $attributes = $field->attributes();
                 foreach ($attributes as $key => $value) {
                     $mapping[$key] = (string) $value;
-                    $booleanAttributes = array('id', 'reference', 'embed', 'unique', 'sparse');
+                    $booleanAttributes = ['id', 'reference', 'embed', 'unique', 'sparse'];
                     if (in_array($key, $booleanAttributes)) {
-                        $mapping[$key] = ('true' === $mapping[$key]);
+                        $mapping[$key] = ($mapping[$key] === 'true');
                     }
                 }
                 if (isset($mapping['id']) && $mapping['id'] === true && isset($mapping['strategy'])) {
-                    $mapping['options'] = array();
+                    $mapping['options'] = [];
                     if (isset($field->{'id-generator-option'})) {
                         foreach ($field->{'id-generator-option'} as $generatorOptions) {
                             $attributesGenerator = iterator_to_array($generatorOptions->attributes());
@@ -134,15 +148,15 @@ public function loadMetadataForClass($className, \Doctrine\Common\Persistence\Ma
                 }
 
                 if (isset($attributes['not-saved'])) {
-                    $mapping['notSaved'] = ('true' === (string) $attributes['not-saved']);
+                    $mapping['notSaved'] = ((string) $attributes['not-saved'] === 'true');
                 }
 
                 if (isset($attributes['also-load'])) {
                     $mapping['alsoLoadFields'] = explode(',', $attributes['also-load']);
                 } elseif (isset($attributes['version'])) {
-                    $mapping['version'] = ('true' === (string) $attributes['version']);
+                    $mapping['version'] = ((string) $attributes['version'] === 'true');
                 } elseif (isset($attributes['lock'])) {
-                    $mapping['lock'] = ('true' === (string) $attributes['lock']);
+                    $mapping['lock'] = ((string) $attributes['lock'] === 'true');
                 }
 
                 $this->addFieldMapping($class, $mapping);
@@ -193,27 +207,27 @@ private function addFieldMapping(ClassMetadata $class, $mapping)
         $class->mapField($mapping);
 
         // Index this field if either "index", "unique", or "sparse" are set
-        if ( ! (isset($mapping['index']) || isset($mapping['unique']) || isset($mapping['sparse']))) {
+        if (! (isset($mapping['index']) || isset($mapping['unique']) || isset($mapping['sparse']))) {
             return;
         }
 
-        $keys = array($name => $mapping['order'] ?? 'asc');
-        $options = array();
+        $keys = [$name => $mapping['order'] ?? 'asc'];
+        $options = [];
 
         if (isset($mapping['background'])) {
-            $options['background'] = (boolean) $mapping['background'];
+            $options['background'] = (bool) $mapping['background'];
         }
         if (isset($mapping['drop-dups'])) {
-            $options['dropDups'] = (boolean) $mapping['drop-dups'];
+            $options['dropDups'] = (bool) $mapping['drop-dups'];
         }
         if (isset($mapping['index-name'])) {
             $options['name'] = (string) $mapping['index-name'];
         }
         if (isset($mapping['sparse'])) {
-            $options['sparse'] = (boolean) $mapping['sparse'];
+            $options['sparse'] = (bool) $mapping['sparse'];
         }
         if (isset($mapping['unique'])) {
-            $options['unique'] = (boolean) $mapping['unique'];
+            $options['unique'] = (bool) $mapping['unique'];
         }
 
         $class->addIndex($keys, $options);
@@ -222,15 +236,15 @@ private function addFieldMapping(ClassMetadata $class, $mapping)
     private function addEmbedMapping(ClassMetadata $class, $embed, $type)
     {
         $attributes = $embed->attributes();
-        $defaultStrategy = $type == 'one' ? ClassMetadata::STORAGE_STRATEGY_SET : CollectionHelper::DEFAULT_STRATEGY;
-        $mapping = array(
+        $defaultStrategy = $type === 'one' ? ClassMetadata::STORAGE_STRATEGY_SET : CollectionHelper::DEFAULT_STRATEGY;
+        $mapping = [
             'type'            => $type,
             'embedded'        => true,
             'targetDocument'  => isset($attributes['target-document']) ? (string) $attributes['target-document'] : null,
             'collectionClass' => isset($attributes['collection-class']) ? (string) $attributes['collection-class'] : null,
             'name'            => (string) $attributes['field'],
             'strategy'        => (string) ($attributes['strategy'] ?? $defaultStrategy),
-        );
+        ];
         if (isset($attributes['fieldName'])) {
             $mapping['fieldName'] = (string) $attributes['fieldName'];
         }
@@ -248,7 +262,7 @@ private function addEmbedMapping(ClassMetadata $class, $embed, $type)
             $mapping['defaultDiscriminatorValue'] = (string) $embed->{'default-discriminator-value'}['value'];
         }
         if (isset($attributes['not-saved'])) {
-            $mapping['notSaved'] = ('true' === (string) $attributes['not-saved']);
+            $mapping['notSaved'] = ((string) $attributes['not-saved'] === 'true');
         }
         if (isset($attributes['also-load'])) {
             $mapping['alsoLoadFields'] = explode(',', $attributes['also-load']);
@@ -259,14 +273,14 @@ private function addEmbedMapping(ClassMetadata $class, $embed, $type)
     private function addReferenceMapping(ClassMetadata $class, $reference, $type)
     {
         $cascade = array_keys((array) $reference->cascade);
-        if (1 === count($cascade)) {
+        if (count($cascade) === 1) {
             $cascade = current($cascade) ?: next($cascade);
         }
         $attributes = $reference->attributes();
-        $defaultStrategy = $type == 'one' ? ClassMetadata::STORAGE_STRATEGY_SET : CollectionHelper::DEFAULT_STRATEGY;
-        $mapping = array(
+        $defaultStrategy = $type === 'one' ? ClassMetadata::STORAGE_STRATEGY_SET : CollectionHelper::DEFAULT_STRATEGY;
+        $mapping = [
             'cascade'          => $cascade,
-            'orphanRemoval'    => isset($attributes['orphan-removal']) ? ('true' === (string) $attributes['orphan-removal']) : false,
+            'orphanRemoval'    => isset($attributes['orphan-removal']) ? ((string) $attributes['orphan-removal'] === 'true') : false,
             'type'             => $type,
             'reference'        => true,
             'storeAs'          => (string) ($attributes['store-as'] ?? ClassMetadata::REFERENCE_STORE_AS_DB_REF),
@@ -277,10 +291,10 @@ private function addReferenceMapping(ClassMetadata $class, $reference, $type)
             'inversedBy'       => isset($attributes['inversed-by']) ? (string) $attributes['inversed-by'] : null,
             'mappedBy'         => isset($attributes['mapped-by']) ? (string) $attributes['mapped-by'] : null,
             'repositoryMethod' => isset($attributes['repository-method']) ? (string) $attributes['repository-method'] : null,
-            'limit'            => isset($attributes['limit']) ? (integer) $attributes['limit'] : null,
-            'skip'             => isset($attributes['skip']) ? (integer) $attributes['skip'] : null,
+            'limit'            => isset($attributes['limit']) ? (int) $attributes['limit'] : null,
+            'skip'             => isset($attributes['skip']) ? (int) $attributes['skip'] : null,
             'prime'            => [],
-        );
+        ];
 
         if (isset($attributes['fieldName'])) {
             $mapping['fieldName'] = (string) $attributes['fieldName'];
@@ -311,7 +325,7 @@ private function addReferenceMapping(ClassMetadata $class, $reference, $type)
             }
         }
         if (isset($attributes['not-saved'])) {
-            $mapping['notSaved'] = ('true' === (string) $attributes['not-saved']);
+            $mapping['notSaved'] = ((string) $attributes['not-saved'] === 'true');
         }
         if (isset($attributes['also-load'])) {
             $mapping['alsoLoadFields'] = explode(',', $attributes['also-load']);
@@ -330,28 +344,28 @@ private function addIndex(ClassMetadata $class, \SimpleXmlElement $xmlIndex)
     {
         $attributes = $xmlIndex->attributes();
 
-        $keys = array();
+        $keys = [];
 
         foreach ($xmlIndex->{'key'} as $key) {
             $keys[(string) $key['name']] = (string) ($key['order'] ?? 'asc');
         }
 
-        $options = array();
+        $options = [];
 
         if (isset($attributes['background'])) {
-            $options['background'] = ('true' === (string) $attributes['background']);
+            $options['background'] = ((string) $attributes['background'] === 'true');
         }
         if (isset($attributes['drop-dups'])) {
-            $options['dropDups'] = ('true' === (string) $attributes['drop-dups']);
+            $options['dropDups'] = ((string) $attributes['drop-dups'] === 'true');
         }
         if (isset($attributes['name'])) {
             $options['name'] = (string) $attributes['name'];
         }
         if (isset($attributes['sparse'])) {
-            $options['sparse'] = ('true' === (string) $attributes['sparse']);
+            $options['sparse'] = ((string) $attributes['sparse'] === 'true');
         }
         if (isset($attributes['unique'])) {
-            $options['unique'] = ('true' === (string) $attributes['unique']);
+            $options['unique'] = ((string) $attributes['unique'] === 'true');
         }
 
         if (isset($xmlIndex->{'option'})) {
@@ -362,7 +376,7 @@ private function addIndex(ClassMetadata $class, \SimpleXmlElement $xmlIndex)
                 } elseif ($value === 'false') {
                     $value = false;
                 } elseif (is_numeric($value)) {
-                    $value = preg_match('/^[-]?\d+$/', $value) ? (integer) $value : (float) $value;
+                    $value = preg_match('/^[-]?\d+$/', $value) ? (int) $value : (float) $value;
                 }
                 $options[(string) $option['name']] = $value;
             }
@@ -422,7 +436,7 @@ private function getPartialFilterExpression(\SimpleXMLElement $fields)
             } elseif ($value === 'false') {
                 $value = false;
             } elseif (is_numeric($value)) {
-                $value = preg_match('/^[-]?\d+$/', $value) ? (integer) $value : (float) $value;
+                $value = preg_match('/^[-]?\d+$/', $value) ? (int) $value : (float) $value;
             }
 
             $partialFilterExpression[(string) $field['name']] = $operator ? ['$' . $operator => $value] : $value;
@@ -435,14 +449,14 @@ private function setShardKey(ClassMetadata $class, \SimpleXmlElement $xmlShardke
     {
         $attributes = $xmlShardkey->attributes();
 
-        $keys = array();
-        $options = array();
+        $keys = [];
+        $options = [];
         foreach ($xmlShardkey->{'key'} as $key) {
             $keys[(string) $key['name']] = (string) ($key['order'] ?? 'asc');
         }
 
         if (isset($attributes['unique'])) {
-            $options['unique'] = ('true' === (string) $attributes['unique']);
+            $options['unique'] = ((string) $attributes['unique'] === 'true');
         }
 
         if (isset($attributes['numInitialChunks'])) {
@@ -457,7 +471,7 @@ private function setShardKey(ClassMetadata $class, \SimpleXmlElement $xmlShardke
                 } elseif ($value === 'false') {
                     $value = false;
                 } elseif (is_numeric($value)) {
-                    $value = preg_match('/^[-]?\d+$/', $value) ? (integer) $value : (float) $value;
+                    $value = preg_match('/^[-]?\d+$/', $value) ? (int) $value : (float) $value;
                 }
                 $options[(string) $option['name']] = $value;
             }
@@ -495,10 +509,10 @@ private function transformReadPreference($xmlReadPreference)
      */
     protected function loadMappingFile($file)
     {
-        $result = array();
+        $result = [];
         $xmlElement = simplexml_load_file($file);
 
-        foreach (array('document', 'embedded-document', 'mapped-superclass', 'query-result-document') as $type) {
+        foreach (['document', 'embedded-document', 'mapped-superclass', 'query-result-document'] as $type) {
             if (isset($xmlElement->$type)) {
                 foreach ($xmlElement->$type as $documentElement) {
                     $documentName = (string) $documentElement['name'];
diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/MappingException.php b/lib/Doctrine/ODM/MongoDB/Mapping/MappingException.php
index 7b53880084..e15d0756a9 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/MappingException.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/MappingException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Mapping;
 
 use Doctrine\Common\Persistence\Mapping\MappingException as BaseMappingException;
@@ -7,7 +9,6 @@
 /**
  * Class for all exceptions related to the Doctrine MongoDB ODM
  *
- * @since       1.0
  */
 class MappingException extends BaseMappingException
 {
@@ -104,7 +105,7 @@ public static function discriminatorFieldConflict($document, $fieldName)
      * Throws an exception that indicates that a class used in a discriminator map does not exist.
      * An example would be an outdated (maybe renamed) classname.
      *
-     * @param string $className The class that could not be found
+     * @param string $className   The class that could not be found
      * @param string $owningClass The class that declares the discriminator map.
      * @return MappingException
      */
@@ -119,7 +120,7 @@ public static function invalidClassInDiscriminatorMap($className, $owningClass)
     /**
      * Throws an exception that indicates a discriminator value does not exist in a map
      *
-     * @param string $value The discriminator value that could not be found
+     * @param string $value       The discriminator value that could not be found
      * @param string $owningClass The class that declares the discriminator map
      * @return MappingException
      */
@@ -152,7 +153,6 @@ public static function classIsNotAValidDocument($className)
      * within the stacktrace
      *
      * @param string $document The document's name
-     * @param \ReflectionException $previousException
      * @return \Doctrine\ODM\MongoDB\Mapping\MappingException
      */
     public static function reflectionFailure($document, \ReflectionException $previousException)
diff --git a/lib/Doctrine/ODM/MongoDB/MongoDBException.php b/lib/Doctrine/ODM/MongoDB/MongoDBException.php
index 376d360a43..fec82574fe 100644
--- a/lib/Doctrine/ODM/MongoDB/MongoDBException.php
+++ b/lib/Doctrine/ODM/MongoDB/MongoDBException.php
@@ -1,11 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
+use function array_slice;
+use function end;
+use function get_class;
+use function is_array;
+use function is_object;
+use function join;
+use function sprintf;
+
 /**
  * Class for all exceptions related to the Doctrine MongoDB ODM
  *
- * @since       1.0
  */
 class MongoDBException extends \Exception
 {
@@ -67,19 +76,20 @@ public static function cannotPersistMappedSuperclass($className)
      */
     public static function invalidDocumentRepository($className)
     {
-        return new self("Invalid repository class '".$className."'. It must be a Doctrine\Common\Persistence\ObjectRepository.");
+        return new self("Invalid repository class '" . $className . "'. It must be a Doctrine\Common\Persistence\ObjectRepository.");
     }
 
     /**
-     * @param string $type
+     * @param string       $type
      * @param string|array $expected
-     * @param mixed $got
+     * @param mixed        $got
      * @return MongoDBException
      */
     public static function invalidValueForType($type, $expected, $got)
     {
         if (is_array($expected)) {
-            $expected = sprintf('%s or %s',
+            $expected = sprintf(
+                '%s or %s',
                 join(', ', array_slice($expected, 0, -1)),
                 end($expected)
             );
@@ -121,7 +131,8 @@ public static function shardKeyFieldMissing($field, $className)
      */
     public static function failedToEnableSharding($dbName, $errorMessage)
     {
-        return new self(sprintf('Failed to enable sharding for database "%s". Error from MongoDB: %s',
+        return new self(sprintf(
+            'Failed to enable sharding for database "%s". Error from MongoDB: %s',
             $dbName,
             $errorMessage
         ));
@@ -134,7 +145,8 @@ public static function failedToEnableSharding($dbName, $errorMessage)
      */
     public static function failedToEnsureDocumentSharding($className, $errorMessage)
     {
-        return new self(sprintf('Failed to ensure sharding for document "%s". Error from MongoDB: %s',
+        return new self(sprintf(
+            'Failed to ensure sharding for document "%s". Error from MongoDB: %s',
             $className,
             $errorMessage
         ));
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection.php
index cfe5e2bb2a..991ae58802 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection.php
@@ -1,17 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\Common\Collections\Collection as BaseCollection;
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionTrait;
-use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
 
 /**
  * A PersistentCollection represents a collection of elements that have persistent state.
  *
- * @since 1.0
  */
 class PersistentCollection implements PersistentCollectionInterface
 {
@@ -19,8 +18,6 @@ class PersistentCollection implements PersistentCollectionInterface
 
     /**
      * @param BaseCollection $coll
-     * @param DocumentManager $dm
-     * @param UnitOfWork $uow
      */
     public function __construct(BaseCollection $coll, DocumentManager $dm, UnitOfWork $uow)
     {
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/AbstractPersistentCollectionFactory.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/AbstractPersistentCollectionFactory.php
index 99e8ffa635..1e5164ba1f 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/AbstractPersistentCollectionFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/AbstractPersistentCollectionFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -10,14 +12,13 @@
 /**
  * Abstract factory for creating persistent collection classes.
  *
- * @since 1.1
  */
 abstract class AbstractPersistentCollectionFactory implements PersistentCollectionFactory
 {
     /**
      * {@inheritdoc}
      */
-    public function create(DocumentManager $dm, array $mapping, BaseCollection $coll = null)
+    public function create(DocumentManager $dm, array $mapping, ?BaseCollection $coll = null)
     {
         if ($coll === null) {
             $coll = ! empty($mapping['collectionClass'])
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionFactory.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionFactory.php
index 13e4ca0b51..3466b5b09d 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionFactory.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 /**
  * Default factory class for persistent collection classes.
  *
- * @since 1.1
  */
 final class DefaultPersistentCollectionFactory extends AbstractPersistentCollectionFactory
 {
@@ -14,6 +15,6 @@ final class DefaultPersistentCollectionFactory extends AbstractPersistentCollect
      */
     protected function createCollectionClass($collectionClass)
     {
-        return new $collectionClass;
+        return new $collectionClass();
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionGenerator.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionGenerator.php
index a0c4b51d13..cf93965ff0 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/DefaultPersistentCollectionGenerator.php
@@ -1,13 +1,35 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\ODM\MongoDB\Configuration;
+use const DIRECTORY_SEPARATOR;
+use function array_map;
+use function array_pop;
+use function class_exists;
+use function dirname;
+use function explode;
+use function file_exists;
+use function file_put_contents;
+use function implode;
+use function interface_exists;
+use function is_dir;
+use function is_writable;
+use function join;
+use function method_exists;
+use function mkdir;
+use function rename;
+use function str_replace;
+use function strtolower;
+use function substr;
+use function uniqid;
+use function var_export;
 
 /**
  * Default generator for custom PersistentCollection classes.
  *
- * @since 1.1
  */
 final class DefaultPersistentCollectionGenerator implements PersistentCollectionGenerator
 {
@@ -52,16 +74,16 @@ public function generateClass($class, $dir)
     public function loadClass($collectionClass, $autoGenerate)
     {
         // These checks are not in __construct() because of BC and should be moved for 2.0
-        if ( ! $this->collectionDir) {
+        if (! $this->collectionDir) {
             throw PersistentCollectionException::directoryRequired();
         }
-        if ( ! $this->collectionNamespace) {
+        if (! $this->collectionNamespace) {
             throw PersistentCollectionException::namespaceRequired();
         }
 
         $collClassName = str_replace('\\', '', $collectionClass) . 'Persistent';
         $className = $this->collectionNamespace . '\\' . $collClassName;
-        if ( ! class_exists($className, false)) {
+        if (! class_exists($className, false)) {
             $fileName = $this->collectionDir . DIRECTORY_SEPARATOR . $collClassName . '.php';
             switch ($autoGenerate) {
                 case Configuration::AUTOGENERATE_NEVER:
@@ -74,7 +96,7 @@ public function loadClass($collectionClass, $autoGenerate)
                     break;
 
                 case Configuration::AUTOGENERATE_FILE_NOT_EXISTS:
-                    if ( ! file_exists($fileName)) {
+                    if (! file_exists($fileName)) {
                         $this->generateCollectionClass($collectionClass, $className, $fileName);
                     }
                     require $fileName;
@@ -129,8 +151,7 @@ public function __construct(BaseCollection \$coll, DocumentManager \$dm, UnitOfW
         $rc = new \ReflectionClass($for);
         $rt = new \ReflectionClass('Doctrine\\ODM\\MongoDB\\PersistentCollection\\PersistentCollectionTrait');
         foreach ($rc->getMethods(\ReflectionMethod::IS_PUBLIC) as $method) {
-            if (
-                $rt->hasMethod($method->name) ||
+            if ($rt->hasMethod($method->name) ||
                 $method->isConstructor() ||
                 $method->isFinal() ||
                 $method->isStatic()
@@ -142,17 +163,17 @@ public function __construct(BaseCollection \$coll, DocumentManager \$dm, UnitOfW
         $code .= "}\n";
 
         if ($fileName === false) {
-            if ( ! class_exists($targetFqcn)) {
+            if (! class_exists($targetFqcn)) {
                 eval(substr($code, 5));
             }
         } else {
             $parentDirectory = dirname($fileName);
 
-            if ( ! is_dir($parentDirectory) && (false === @mkdir($parentDirectory, 0775, true))) {
+            if (! is_dir($parentDirectory) && (@mkdir($parentDirectory, 0775, true) === false)) {
                 throw PersistentCollectionException::directoryNotWritable();
             }
 
-            if ( ! is_writable($parentDirectory)) {
+            if (! is_writable($parentDirectory)) {
                 throw PersistentCollectionException::directoryNotWritable();
             }
 
@@ -186,14 +207,13 @@ public function {$method->name}($parametersString){$this->getMethodReturnType($m
     }
 
     /**
-     * @param \ReflectionMethod $method
      *
      * @return string
      */
     private function buildParametersString(\ReflectionMethod $method)
     {
         $parameters = $method->getParameters();
-        $parameterDefinitions = array();
+        $parameterDefinitions = [];
 
         /* @var $param \ReflectionParameter */
         foreach ($parameters as $param) {
@@ -227,7 +247,6 @@ private function buildParametersString(\ReflectionMethod $method)
     }
 
     /**
-     * @param \ReflectionParameter $parameter
      *
      * @return string|null
      */
@@ -282,7 +301,6 @@ function (\ReflectionParameter $parameter) {
     }
 
     /**
-     * @param \ReflectionMethod $method
      *
      * @return string
      *
@@ -290,16 +308,13 @@ function (\ReflectionParameter $parameter) {
      */
     private function getMethodReturnType(\ReflectionMethod $method)
     {
-        if ( ! method_exists($method, 'hasReturnType') || ! $method->hasReturnType()) {
+        if (! method_exists($method, 'hasReturnType') || ! $method->hasReturnType()) {
             return '';
         }
         return ': ' . $this->formatType($method->getReturnType(), $method);
     }
 
     /**
-     * @param \ReflectionType $type
-     * @param \ReflectionMethod $method
-     * @param \ReflectionParameter|null $parameter
      *
      * @return string
      *
@@ -308,18 +323,18 @@ private function getMethodReturnType(\ReflectionMethod $method)
     private function formatType(
         \ReflectionType $type,
         \ReflectionMethod $method,
-        \ReflectionParameter $parameter = null
+        ?\ReflectionParameter $parameter = null
     ) {
         $name = method_exists($type, 'getName') ? $type->getName() : (string) $type;
         $nameLower = strtolower($name);
-        if ('self' === $nameLower) {
+        if ($nameLower === 'self') {
             $name = $method->getDeclaringClass()->getName();
         }
-        if ('parent' === $nameLower) {
+        if ($nameLower === 'parent') {
             $name = $method->getDeclaringClass()->getParentClass()->getName();
         }
-        if ( ! $type->isBuiltin() && ! class_exists($name) && ! interface_exists($name)) {
-            if (null !== $parameter) {
+        if (! $type->isBuiltin() && ! class_exists($name) && ! interface_exists($name)) {
+            if ($parameter !== null) {
                 throw PersistentCollectionException::invalidParameterTypeHint(
                     $method->getDeclaringClass()->getName(),
                     $method->getName(),
@@ -331,11 +346,11 @@ private function formatType(
                 $method->getName()
             );
         }
-        if ( ! $type->isBuiltin()) {
+        if (! $type->isBuiltin()) {
             $name = '\\' . $name;
         }
         if ($type->allowsNull()
-            && (null === $parameter || ! $parameter->isDefaultValueAvailable() || null !== $parameter->getDefaultValue())
+            && ($parameter === null || ! $parameter->isDefaultValueAvailable() || $parameter->getDefaultValue() !== null)
         ) {
             $name = '?' . $name;
         }
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionException.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionException.php
index bcdf2e1047..aea90240e2 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionException.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionException.php
@@ -1,13 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\ODM\MongoDB\MongoDBException;
+use function sprintf;
 
 /**
  * MongoDB ODM PersistentCollection Exception.
  *
- * @since 1.1
  */
 class PersistentCollectionException extends MongoDBException
 {
@@ -27,10 +29,9 @@ public static function namespaceRequired()
     }
 
     /**
-     * @param string          $className
-     * @param string          $methodName
-     * @param string          $parameterName
-     * @param \Exception|null $previous
+     * @param string $className
+     * @param string $methodName
+     * @param string $parameterName
      *
      * @return self
      */
@@ -38,7 +39,7 @@ public static function invalidParameterTypeHint(
         $className,
         $methodName,
         $parameterName,
-        \Exception $previous = null
+        ?\Throwable $previous = null
     ) {
         return new self(
             sprintf(
@@ -55,11 +56,10 @@ public static function invalidParameterTypeHint(
     /**
      * @param string $className
      * @param string $methodName
-     * @param \Exception|null $previous
      *
      * @return self
      */
-    public static function invalidReturnTypeHint($className, $methodName, \Exception $previous = null)
+    public static function invalidReturnTypeHint($className, $methodName, ?\Throwable $previous = null)
     {
         return new self(
             sprintf(
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionFactory.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionFactory.php
index 8381971cef..3a6d0edd4f 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\Common\Collections\Collection as BaseCollection;
@@ -8,17 +10,16 @@
 /**
  * Interface for persistent collection classes factory.
  *
- * @since 1.1
  */
 interface PersistentCollectionFactory
 {
     /**
      * Creates specified persistent collection to work with given collection class.
      *
-     * @param DocumentManager $dm DocumentManager with which collection is associated
-     * @param array $mapping Mapping of field holding collection
-     * @param BaseCollection $coll Collection to be decorated
+     * @param DocumentManager $dm      DocumentManager with which collection is associated
+     * @param array           $mapping Mapping of field holding collection
+     * @param BaseCollection  $coll    Collection to be decorated
      * @return PersistentCollectionInterface
      */
-    public function create(DocumentManager $dm, array $mapping, BaseCollection $coll = null);
+    public function create(DocumentManager $dm, array $mapping, ?BaseCollection $coll = null);
 }
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionGenerator.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionGenerator.php
index 87413471f3..26f3d3b604 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionGenerator.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionGenerator.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 /**
  * Interface for PersistentCollection classes generator.
  *
- * @since 1.1
  */
 interface PersistentCollectionGenerator
 {
@@ -13,7 +14,7 @@ interface PersistentCollectionGenerator
      * Loads persistent collection class.
      *
      * @param string $collectionClass FQCN of base collection class
-     * @param int $autoGenerate
+     * @param int    $autoGenerate
      * @return string FQCN of generated class
      */
     public function loadClass($collectionClass, $autoGenerate);
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionInterface.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionInterface.php
index 17b980ae08..d76e93a681 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionInterface.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\Common\Collections\Collection;
@@ -11,14 +13,12 @@
  * Interface for persistent collection classes.
  *
  * @internal
- * @since 1.1
  */
 interface PersistentCollectionInterface extends Collection
 {
     /**
      * Sets the document manager and unit of work (used during merge operations).
      *
-     * @param DocumentManager $dm
      */
     public function setDocumentManager(DocumentManager $dm);
 
@@ -60,14 +60,14 @@ public function initialize();
      * Gets a boolean flag indicating whether this collection is dirty which means
      * its state needs to be synchronized with the database.
      *
-     * @return boolean TRUE if the collection is dirty, FALSE otherwise.
+     * @return bool TRUE if the collection is dirty, FALSE otherwise.
      */
     public function isDirty();
 
     /**
      * Sets a boolean flag, indicating whether this collection is dirty.
      *
-     * @param boolean $dirty Whether the collection should be marked dirty or not.
+     * @param bool $dirty Whether the collection should be marked dirty or not.
      */
     public function setDirty($dirty);
 
@@ -77,7 +77,7 @@ public function setDirty($dirty);
      * describes the association between the owner and the elements of the collection.
      *
      * @param object $document
-     * @param array $mapping
+     * @param array  $mapping
      */
     public function setOwner($document, array $mapping);
 
@@ -157,14 +157,14 @@ public function getTypeClass();
     /**
      * Sets the initialized flag of the collection, forcing it into that state.
      *
-     * @param boolean $bool
+     * @param bool $bool
      */
     public function setInitialized($bool);
 
     /**
      * Checks whether this collection has been initialized.
      *
-     * @return boolean
+     * @return bool
      */
     public function isInitialized();
 
diff --git a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionTrait.php b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionTrait.php
index e18a54a3de..fd4d52d801 100644
--- a/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionTrait.php
+++ b/lib/Doctrine/ODM/MongoDB/PersistentCollection/PersistentCollectionTrait.php
@@ -1,18 +1,25 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\PersistentCollection;
 
 use Doctrine\Common\Collections\Collection as BaseCollection;
 use Doctrine\ODM\MongoDB\DocumentManager;
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\MongoDBException;
 use Doctrine\ODM\MongoDB\UnitOfWork;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use function array_udiff;
+use function array_udiff_assoc;
+use function array_values;
+use function count;
+use function get_class;
+use function is_object;
+use function spl_object_hash;
 
 /**
  * Trait with methods needed to implement PersistentCollectionInterface.
  *
- * @since 1.1
  */
 trait PersistentCollectionTrait
 {
@@ -22,7 +29,7 @@ trait PersistentCollectionTrait
      *
      * @var array
      */
-    private $snapshot = array();
+    private $snapshot = [];
 
     /**
      * Collection's owning entity
@@ -40,14 +47,14 @@ trait PersistentCollectionTrait
      * Whether the collection is dirty and needs to be synchronized with the database
      * when the UnitOfWork that manages its persistent state commits.
      *
-     * @var boolean
+     * @var bool
      */
     private $isDirty = false;
 
     /**
      * Whether the collection has already been initialized.
      *
-     * @var boolean
+     * @var bool
      */
     private $initialized = true;
 
@@ -77,14 +84,14 @@ trait PersistentCollectionTrait
      *
      * @var array
      */
-    private $mongoData = array();
+    private $mongoData = [];
 
     /**
      * Any hints to account for during reconstitution/lookup of the documents.
      *
      * @var array
      */
-    private $hints = array();
+    private $hints = [];
 
     /** {@inheritdoc} */
     public function setDocumentManager(DocumentManager $dm)
@@ -124,7 +131,7 @@ public function initialize()
             return;
         }
 
-        $newObjects = array();
+        $newObjects = [];
 
         if ($this->isDirty) {
             // Remember any NEW objects added through add()
@@ -137,7 +144,7 @@ public function initialize()
         $this->uow->loadCollection($this);
         $this->takeSnapshot();
 
-        $this->mongoData = array();
+        $this->mongoData = [];
 
         // Reattach any NEW objects added through add()
         if ($newObjects) {
@@ -216,7 +223,7 @@ public function takeSnapshot()
     /** {@inheritdoc} */
     public function clearSnapshot()
     {
-        $this->snapshot = array();
+        $this->snapshot = [];
         $this->isDirty = $this->coll->count() ? true : false;
     }
 
@@ -232,7 +239,9 @@ public function getDeleteDiff()
         return array_udiff_assoc(
             $this->snapshot,
             $this->coll->toArray(),
-            function ($a, $b) { return $a === $b ? 0 : 1; }
+            function ($a, $b) {
+                return $a === $b ? 0 : 1;
+            }
         );
     }
 
@@ -257,7 +266,9 @@ public function getInsertDiff()
         return array_udiff_assoc(
             $this->coll->toArray(),
             $this->snapshot,
-            function ($a, $b) { return $a === $b ? 0 : 1; }
+            function ($a, $b) {
+                return $a === $b ? 0 : 1;
+            }
         );
     }
 
@@ -345,7 +356,7 @@ public function removeElement($element)
         $this->initialize();
         $removed = $this->coll->removeElement($element);
 
-        if ( ! $removed) {
+        if (! $removed) {
             return $removed;
         }
 
@@ -522,11 +533,11 @@ public function clear()
             }
         }
 
-        $this->mongoData = array();
+        $this->mongoData = [];
         $this->coll->clear();
 
         // Nothing to do for inverse-side collections
-        if ( ! $this->mapping['isOwningSide']) {
+        if (! $this->mapping['isOwningSide']) {
             return;
         }
 
@@ -558,7 +569,7 @@ public function slice($offset, $length = null)
      */
     public function __sleep()
     {
-        return array('coll', 'initialized');
+        return ['coll', 'initialized'];
     }
 
     /* ArrayAccess implementation */
@@ -587,7 +598,7 @@ public function offsetGet($offset)
      */
     public function offsetSet($offset, $value)
     {
-        if ( ! isset($offset)) {
+        if (! isset($offset)) {
             return $this->doAdd($value, true);
         }
 
@@ -651,7 +662,7 @@ public function __clone()
         $this->initialize();
 
         $this->owner = null;
-        $this->snapshot = array();
+        $this->snapshot = [];
 
         $this->changed();
     }
@@ -660,7 +671,7 @@ public function __clone()
      * Actual logic for adding an element to the collection.
      *
      * @param mixed $value
-     * @param bool $arrayAccess
+     * @param bool  $arrayAccess
      * @return bool
      */
     private function doAdd($value, $arrayAccess)
@@ -686,7 +697,7 @@ private function doAdd($value, $arrayAccess)
      * Actual logic for removing element by its key.
      *
      * @param mixed $offset
-     * @param bool $arrayAccess
+     * @param bool  $arrayAccess
      * @return mixed|void
      */
     private function doRemove($offset, $arrayAccess)
@@ -694,7 +705,7 @@ private function doRemove($offset, $arrayAccess)
         $this->initialize();
         $removed = $arrayAccess ? $this->coll->offsetUnset($offset) : $this->coll->remove($offset);
 
-        if ( ! $removed && ! $arrayAccess) {
+        if (! $removed && ! $arrayAccess) {
             return $removed;
         }
 
@@ -708,8 +719,7 @@ private function doRemove($offset, $arrayAccess)
      *
      * @param mixed $offset
      * @param mixed $value
-     * @param bool $arrayAccess
-     * @return bool
+     * @param bool  $arrayAccess
      */
     private function doSet($offset, $value, $arrayAccess)
     {
@@ -729,7 +739,7 @@ private function doSet($offset, $value, $arrayAccess)
      * Embedded documents are automatically considered as "orphan removal enabled" because they might have references
      * that require to trigger cascade remove operations.
      *
-     * @return boolean
+     * @return bool
      */
     private function isOrphanRemovalEnabled()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php b/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
index d9ee1c982e..b88ae37baa 100644
--- a/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
+++ b/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Persisters;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -8,6 +10,11 @@
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\UnitOfWork;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use function array_map;
+use function array_reverse;
+use function array_values;
+use function get_class;
+use function implode;
 
 /**
  * The CollectionPersister is responsible for persisting collections of embedded
@@ -19,7 +26,6 @@
  * entire collection or delete/insert individual elements, depending on the
  * mapping strategy.
  *
- * @since       1.0
  */
 class CollectionPersister
 {
@@ -47,9 +53,6 @@ class CollectionPersister
     /**
      * Constructs a new CollectionPersister instance.
      *
-     * @param DocumentManager $dm
-     * @param PersistenceBuilder $pb
-     * @param UnitOfWork $uow
      */
     public function __construct(DocumentManager $dm, PersistenceBuilder $pb, UnitOfWork $uow)
     {
@@ -61,7 +64,6 @@ public function __construct(DocumentManager $dm, PersistenceBuilder $pb, UnitOfW
     /**
      * Deletes a PersistentCollection instance completely from a document using $unset.
      *
-     * @param PersistentCollectionInterface $coll
      * @param array $options
      */
     public function delete(PersistentCollectionInterface $coll, array $options)
@@ -74,7 +76,7 @@ public function delete(PersistentCollectionInterface $coll, array $options)
             throw new \UnexpectedValueException($mapping['strategy'] . ' delete collection strategy should have been handled by DocumentPersister. Please report a bug in issue tracker');
         }
         list($propertyPath, $parent) = $this->getPathAndParent($coll);
-        $query = array('$unset' => array($propertyPath => true));
+        $query = ['$unset' => [$propertyPath => true]];
         $this->executeQuery($parent, $query, $options);
     }
 
@@ -82,7 +84,6 @@ public function delete(PersistentCollectionInterface $coll, array $options)
      * Updates a PersistentCollection instance deleting removed rows and
      * inserting new rows.
      *
-     * @param PersistentCollectionInterface $coll
      * @param array $options
      */
     public function update(PersistentCollectionInterface $coll, array $options)
@@ -123,7 +124,6 @@ public function update(PersistentCollectionInterface $coll, array $options)
      * set as a BSON array, which means the collection elements will be
      * reindexed numerically before storage.
      *
-     * @param PersistentCollectionInterface $coll
      * @param array $options
      */
     private function setCollection(PersistentCollectionInterface $coll, array $options)
@@ -132,7 +132,7 @@ private function setCollection(PersistentCollectionInterface $coll, array $optio
         $coll->initialize();
         $mapping = $coll->getMapping();
         $setData = $this->pb->prepareAssociatedCollectionValue($coll, CollectionHelper::usesSet($mapping['strategy']));
-        $query = array('$set' => array($propertyPath => $setData));
+        $query = ['$set' => [$propertyPath => $setData]];
         $this->executeQuery($parent, $query, $options);
     }
 
@@ -142,7 +142,6 @@ private function setCollection(PersistentCollectionInterface $coll, array $optio
      * This method is intended to be used with the "pushAll" and "addToSet"
      * strategies.
      *
-     * @param PersistentCollectionInterface $coll
      * @param array $options
      */
     private function deleteElements(PersistentCollectionInterface $coll, array $options)
@@ -155,7 +154,7 @@ private function deleteElements(PersistentCollectionInterface $coll, array $opti
 
         list($propertyPath, $parent) = $this->getPathAndParent($coll);
 
-        $query = array('$unset' => array());
+        $query = ['$unset' => []];
 
         foreach ($deleteDiff as $key => $document) {
             $query['$unset'][$propertyPath . '.' . $key] = true;
@@ -169,7 +168,7 @@ private function deleteElements(PersistentCollectionInterface $coll, array $opti
          * in the element being left in the array as null so we have to pull
          * null values.
          */
-        $this->executeQuery($parent, array('$pull' => array($propertyPath => null)), $options);
+        $this->executeQuery($parent, ['$pull' => [$propertyPath => null]], $options);
     }
 
     /**
@@ -178,7 +177,6 @@ private function deleteElements(PersistentCollectionInterface $coll, array $opti
      * This method is intended to be used with the "pushAll" and "addToSet"
      * strategies.
      *
-     * @param PersistentCollectionInterface $coll
      * @param array $options
      */
     private function insertElements(PersistentCollectionInterface $coll, array $options)
@@ -207,8 +205,12 @@ private function insertElements(PersistentCollectionInterface $coll, array $opti
         list($propertyPath, $parent) = $this->getPathAndParent($coll);
 
         $callback = isset($mapping['embedded'])
-            ? function($v) use ($mapping) { return $this->pb->prepareEmbeddedDocumentValue($mapping, $v); }
-            : function($v) use ($mapping) { return $this->pb->prepareReferencedDocumentValue($mapping, $v); };
+            ? function ($v) use ($mapping) {
+                return $this->pb->prepareEmbeddedDocumentValue($mapping, $v);
+            }
+            : function ($v) use ($mapping) {
+                return $this->pb->prepareReferencedDocumentValue($mapping, $v);
+            };
 
         $value = array_values(array_map($callback, $insertDiff));
 
@@ -228,15 +230,14 @@ private function insertElements(PersistentCollectionInterface $coll, array $opti
      *     list($path, $parent) = $this->getPathAndParent($coll)
      *     </code>
      *
-     * @param PersistentCollectionInterface $coll
      * @return array $pathAndParent
      */
     private function getPathAndParent(PersistentCollectionInterface $coll)
     {
         $mapping = $coll->getMapping();
-        $fields = array();
+        $fields = [];
         $parent = $coll->getOwner();
-        while (null !== ($association = $this->uow->getParentAssociation($parent))) {
+        while (($association = $this->uow->getParentAssociation($parent)) !== null) {
             list($m, $owner, $field) = $association;
             if (isset($m['reference'])) {
                 break;
@@ -249,22 +250,22 @@ private function getPathAndParent(PersistentCollectionInterface $coll)
         if ($propertyPath) {
             $path = $propertyPath . '.' . $path;
         }
-        return array($path, $parent);
+        return [$path, $parent];
     }
 
     /**
      * Executes a query updating the given document.
      *
      * @param object $document
-     * @param array $newObj
-     * @param array $options
+     * @param array  $newObj
+     * @param array  $options
      */
     private function executeQuery($document, array $newObj, array $options)
     {
         $className = get_class($document);
         $class = $this->dm->getClassMetadata($className);
         $id = $class->getDatabaseIdentifierValue($this->uow->getDocumentIdentifier($document));
-        $query = array('_id' => $id);
+        $query = ['_id' => $id];
         if ($class->isVersioned) {
             $query[$class->fieldMappings[$class->versionField]['name']] = $class->reflFields[$class->versionField]->getValue($document);
         }
diff --git a/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php b/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php
index 8cf54e94ef..c394b60f86 100644
--- a/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php
+++ b/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php
@@ -1,17 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Persisters;
 
 use Doctrine\Common\EventManager;
 use Doctrine\Common\Persistence\Mapping\MappingException;
 use Doctrine\ODM\MongoDB\DocumentManager;
+use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\Iterator\CachingIterator;
 use Doctrine\ODM\MongoDB\Iterator\HydratingIterator;
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
 use Doctrine\ODM\MongoDB\Iterator\PrimingIterator;
-use Doctrine\ODM\MongoDB\Query\ReferencePrimer;
-use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
-use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\LockException;
 use Doctrine\ODM\MongoDB\LockMode;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
@@ -20,17 +20,41 @@
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\Query\CriteriaMerger;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Doctrine\ODM\MongoDB\Query\ReferencePrimer;
 use Doctrine\ODM\MongoDB\Types\Type;
 use Doctrine\ODM\MongoDB\UnitOfWork;
+use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use MongoDB\BSON\ObjectId;
 use MongoDB\Collection;
 use MongoDB\Driver\Cursor;
 use MongoDB\Driver\Exception\Exception as DriverException;
 use MongoDB\Driver\Exception\WriteException;
+use function array_combine;
+use function array_fill;
+use function array_intersect_key;
+use function array_keys;
+use function array_map;
+use function array_merge;
+use function array_search;
+use function array_slice;
+use function array_values;
+use function count;
+use function explode;
+use function get_class;
+use function get_object_vars;
+use function implode;
+use function in_array;
+use function is_array;
+use function is_object;
+use function is_scalar;
+use function max;
+use function spl_object_hash;
+use function strpos;
+use function strtolower;
 
 /**
  * The DocumentPersister is responsible for persisting documents.
  *
- * @since       1.0
  */
 class DocumentPersister
 {
@@ -81,14 +105,14 @@ class DocumentPersister
      *
      * @var array
      */
-    private $queuedInserts = array();
+    private $queuedInserts = [];
 
     /**
      * Array of queued inserts for the persister to insert.
      *
      * @var array
      */
-    private $queuedUpserts = array();
+    private $queuedUpserts = [];
 
     /**
      * The CriteriaMerger instance.
@@ -114,13 +138,6 @@ class DocumentPersister
     /**
      * Initializes this instance.
      *
-     * @param PersistenceBuilder $pb
-     * @param DocumentManager $dm
-     * @param EventManager $evm
-     * @param UnitOfWork $uow
-     * @param HydratorFactory $hydratorFactory
-     * @param ClassMetadata $class
-     * @param CriteriaMerger $cm
      */
     public function __construct(
         PersistenceBuilder $pb,
@@ -129,7 +146,7 @@ public function __construct(
         UnitOfWork $uow,
         HydratorFactory $hydratorFactory,
         ClassMetadata $class,
-        CriteriaMerger $cm = null
+        ?CriteriaMerger $cm = null
     ) {
         $this->pb = $pb;
         $this->dm = $dm;
@@ -180,7 +197,7 @@ public function getUpserts()
 
     /**
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isQueuedForUpsert($document)
     {
@@ -218,13 +235,13 @@ public function getClassMetadata()
      *
      * @param array $options Options for batchInsert() and update() driver methods
      */
-    public function executeInserts(array $options = array())
+    public function executeInserts(array $options = [])
     {
-        if ( ! $this->queuedInserts) {
+        if (! $this->queuedInserts) {
             return;
         }
 
-        $inserts = array();
+        $inserts = [];
         $options = $this->getWriteOptions($options);
         foreach ($this->queuedInserts as $oid => $document) {
             $data = $this->pb->prepareInsertData($document);
@@ -251,7 +268,7 @@ public function executeInserts(array $options = array())
             try {
                 $this->collection->insertMany($inserts, $options);
             } catch (DriverException $e) {
-                $this->queuedInserts = array();
+                $this->queuedInserts = [];
                 throw $e;
             }
         }
@@ -264,7 +281,7 @@ public function executeInserts(array $options = array())
             $this->handleCollections($document, $options);
         }
 
-        $this->queuedInserts = array();
+        $this->queuedInserts = [];
     }
 
     /**
@@ -276,9 +293,9 @@ public function executeInserts(array $options = array())
      *
      * @param array $options Options for batchInsert() and update() driver methods
      */
-    public function executeUpserts(array $options = array())
+    public function executeUpserts(array $options = [])
     {
-        if ( ! $this->queuedUpserts) {
+        if (! $this->queuedUpserts) {
             return;
         }
 
@@ -347,7 +364,7 @@ private function executeUpsert($document, array $options)
          */
         if (empty($data)) {
             $retry = true;
-            $data = array('$set' => array('_id' => $criteria['_id']));
+            $data = ['$set' => ['_id' => $criteria['_id']]];
         }
 
         try {
@@ -359,17 +376,17 @@ private function executeUpsert($document, array $options)
             }
         }
 
-        $this->collection->updateOne($criteria, array('$set' => new \stdClass), $options);
+        $this->collection->updateOne($criteria, ['$set' => new \stdClass()], $options);
     }
 
     /**
      * Updates the already persisted document if it has any new changesets.
      *
      * @param object $document
-     * @param array $options Array of options to be used with update()
-     * @throws \Doctrine\ODM\MongoDB\LockException
+     * @param array  $options  Array of options to be used with update()
+     * @throws LockException
      */
-    public function update($document, array $options = array())
+    public function update($document, array $options = [])
     {
         $update = $this->pb->prepareUpdateData($document);
 
@@ -383,7 +400,6 @@ public function update($document, array $options = array())
             unset($update['$set']);
         }
 
-
         // Include versioning logic to set the new version value in the database
         // and to ensure the version has not changed since this document object instance
         // was fetched from the database
@@ -402,16 +418,16 @@ public function update($document, array $options = array())
             }
         }
 
-        if ( ! empty($update)) {
+        if (! empty($update)) {
             // Include locking logic so that if the document object in memory is currently
             // locked then it will remove it, otherwise it ensures the document is not locked.
             if ($this->class->isLockable) {
                 $isLocked = $this->class->reflFields[$this->class->lockField]->getValue($document);
                 $lockMapping = $this->class->fieldMappings[$this->class->lockField];
                 if ($isLocked) {
-                    $update['$unset'] = array($lockMapping['name'] => true);
+                    $update['$unset'] = [$lockMapping['name'] => true];
                 } else {
-                    $query[$lockMapping['name']] = array('$exists' => false);
+                    $query[$lockMapping['name']] = ['$exists' => false];
                 }
             }
 
@@ -433,15 +449,15 @@ public function update($document, array $options = array())
      * Removes document from mongo
      *
      * @param mixed $document
-     * @param array $options Array of options to be used with remove()
-     * @throws \Doctrine\ODM\MongoDB\LockException
+     * @param array $options  Array of options to be used with remove()
+     * @throws LockException
      */
-    public function delete($document, array $options = array())
+    public function delete($document, array $options = [])
     {
         $query = $this->getQueryForDocument($document);
 
         if ($this->class->isLockable) {
-            $query[$this->class->lockField] = array('$exists' => false);
+            $query[$this->class->lockField] = ['$exists' => false];
         }
 
         $options = $this->getWriteOptions($options);
@@ -472,20 +488,20 @@ public function refresh($document)
      * If a scalar or MongoDB\BSON\ObjectId is provided for $criteria, it will
      * be used to match an _id value.
      *
-     * @param mixed   $criteria Query criteria
-     * @param object  $document Document to load the data into. If not specified, a new document is created.
-     * @param array   $hints    Hints for document creation
-     * @param integer $lockMode
-     * @param array   $sort     Sort array for Cursor::sort()
-     * @throws \Doctrine\ODM\MongoDB\LockException
+     * @param mixed  $criteria Query criteria
+     * @param object $document Document to load the data into. If not specified, a new document is created.
+     * @param array  $hints    Hints for document creation
+     * @param int    $lockMode
+     * @param array  $sort     Sort array for Cursor::sort()
+     * @throws LockException
      * @return object|null The loaded and managed document instance or null if no document was found
      * @todo Check identity map? loadById method? Try to guess whether $criteria is the id?
      */
-    public function load($criteria, $document = null, array $hints = array(), $lockMode = 0, array $sort = null)
+    public function load($criteria, $document = null, array $hints = [], $lockMode = 0, ?array $sort = null)
     {
         // TODO: remove this
-        if ($criteria === null || is_scalar($criteria) || $criteria instanceof \MongoDB\BSON\ObjectId) {
-            $criteria = array('_id' => $criteria);
+        if ($criteria === null || is_scalar($criteria) || $criteria instanceof ObjectId) {
+            $criteria = ['_id' => $criteria];
         }
 
         $criteria = $this->prepareQueryOrNewObj($criteria);
@@ -493,7 +509,7 @@ public function load($criteria, $document = null, array $hints = array(), $lockM
         $criteria = $this->addFilterToPreparedQuery($criteria);
 
         $options = [];
-        if (null !== $sort) {
+        if ($sort !== null) {
             $options['sort'] = $this->prepareSort($sort);
         }
         $result = $this->collection->findOne($criteria, $options);
@@ -511,28 +527,28 @@ public function load($criteria, $document = null, array $hints = array(), $lockM
     /**
      * Finds documents by a set of criteria.
      *
-     * @param array        $criteria Query criteria
-     * @param array        $sort     Sort array for Cursor::sort()
-     * @param integer|null $limit    Limit for Cursor::limit()
-     * @param integer|null $skip     Skip for Cursor::skip()
+     * @param array    $criteria Query criteria
+     * @param array    $sort     Sort array for Cursor::sort()
+     * @param int|null $limit    Limit for Cursor::limit()
+     * @param int|null $skip     Skip for Cursor::skip()
      * @return Iterator
      */
-    public function loadAll(array $criteria = array(), array $sort = null, $limit = null, $skip = null)
+    public function loadAll(array $criteria = [], ?array $sort = null, $limit = null, $skip = null)
     {
         $criteria = $this->prepareQueryOrNewObj($criteria);
         $criteria = $this->addDiscriminatorToPreparedQuery($criteria);
         $criteria = $this->addFilterToPreparedQuery($criteria);
 
         $options = [];
-        if (null !== $sort) {
+        if ($sort !== null) {
             $options['sort'] = $this->prepareSort($sort);
         }
 
-        if (null !== $limit) {
+        if ($limit !== null) {
             $options['limit'] = $limit;
         }
 
-        if (null !== $skip) {
+        if ($skip !== null) {
             $options['skip'] = $skip;
         }
 
@@ -550,15 +566,15 @@ public function loadAll(array $criteria = array(), array $sort = null, $limit =
      */
     private function getShardKeyQuery($document)
     {
-        if ( ! $this->class->isSharded()) {
-            return array();
+        if (! $this->class->isSharded()) {
+            return [];
         }
 
         $shardKey = $this->class->getShardKey();
         $keys = array_keys($shardKey['keys']);
         $data = $this->uow->getDocumentActualData($document);
 
-        $shardKeyQueryPart = array();
+        $shardKeyQueryPart = [];
         foreach ($keys as $key) {
             $mapping = $this->class->getFieldMappingByDbFieldName($key);
             $this->guardMissingShardKey($document, $key, $data);
@@ -585,8 +601,6 @@ private function getShardKeyQuery($document)
     /**
      * Wraps the supplied base cursor in the corresponding ODM class.
      *
-     * @param Cursor $baseCursor
-     * @return Iterator
      */
     private function wrapCursor(Cursor $baseCursor): Iterator
     {
@@ -597,26 +611,26 @@ private function wrapCursor(Cursor $baseCursor): Iterator
      * Checks whether the given managed document exists in the database.
      *
      * @param object $document
-     * @return boolean TRUE if the document exists in the database, FALSE otherwise.
+     * @return bool TRUE if the document exists in the database, FALSE otherwise.
      */
     public function exists($document)
     {
         $id = $this->class->getIdentifierObject($document);
-        return (boolean) $this->collection->findOne(array('_id' => $id), array('_id'));
+        return (bool) $this->collection->findOne(['_id' => $id], ['_id']);
     }
 
     /**
      * Locks document by storing the lock mode on the mapped lock field.
      *
      * @param object $document
-     * @param int $lockMode
+     * @param int    $lockMode
      */
     public function lock($document, $lockMode)
     {
         $id = $this->uow->getDocumentIdentifier($document);
-        $criteria = array('_id' => $this->class->getDatabaseIdentifierValue($id));
+        $criteria = ['_id' => $this->class->getDatabaseIdentifierValue($id)];
         $lockMapping = $this->class->fieldMappings[$this->class->lockField];
-        $this->collection->updateOne($criteria, array('$set' => array($lockMapping['name'] => $lockMode)));
+        $this->collection->updateOne($criteria, ['$set' => [$lockMapping['name'] => $lockMode]]);
         $this->class->reflFields[$this->class->lockField]->setValue($document, $lockMode);
     }
 
@@ -628,21 +642,21 @@ public function lock($document, $lockMode)
     public function unlock($document)
     {
         $id = $this->uow->getDocumentIdentifier($document);
-        $criteria = array('_id' => $this->class->getDatabaseIdentifierValue($id));
+        $criteria = ['_id' => $this->class->getDatabaseIdentifierValue($id)];
         $lockMapping = $this->class->fieldMappings[$this->class->lockField];
-        $this->collection->updateOne($criteria, array('$unset' => array($lockMapping['name'] => true)));
+        $this->collection->updateOne($criteria, ['$unset' => [$lockMapping['name'] => true]]);
         $this->class->reflFields[$this->class->lockField]->setValue($document, null);
     }
 
     /**
      * Creates or fills a single document object from an query result.
      *
-     * @param object $result The query result.
+     * @param object $result   The query result.
      * @param object $document The document object to fill, if any.
-     * @param array $hints Hints for document creation.
+     * @param array  $hints    Hints for document creation.
      * @return object The filled and managed document object or NULL, if the query result is empty.
      */
-    private function createDocument($result, $document = null, array $hints = array())
+    private function createDocument($result, $document = null, array $hints = [])
     {
         if ($result === null) {
             return null;
@@ -660,7 +674,6 @@ private function createDocument($result, $document = null, array $hints = array(
     /**
      * Loads a PersistentCollection data. Used in the initialize() method.
      *
-     * @param PersistentCollectionInterface $collection
      */
     public function loadCollection(PersistentCollectionInterface $collection)
     {
@@ -698,7 +711,7 @@ private function loadEmbedManyCollection(PersistentCollectionInterface $collecti
                 $this->uow->setParentAssociation($embeddedDocumentObject, $mapping, $owner, $mapping['name'] . '.' . $key);
 
                 $data = $this->hydratorFactory->hydrate($embeddedDocumentObject, $embeddedDocument, $collection->getHints());
-                $id = $embeddedMetadata->identifier && $data[$embeddedMetadata->identifier] ?? null;
+                $id = $data[$embeddedMetadata->identifier] ?? null;
 
                 if (empty($collection->getHints()[Query::HINT_READ_ONLY])) {
                     $this->uow->registerManaged($embeddedDocumentObject, $id, $data);
@@ -716,7 +729,7 @@ private function loadReferenceManyCollectionOwningSide(PersistentCollectionInter
     {
         $hints = $collection->getHints();
         $mapping = $collection->getMapping();
-        $groupedIds = array();
+        $groupedIds = [];
 
         $sorted = isset($mapping['sort']) && $mapping['sort'];
 
@@ -729,7 +742,7 @@ private function loadReferenceManyCollectionOwningSide(PersistentCollectionInter
             $reference = $this->dm->getReference($className, $id);
 
             // no custom sort so add the references right now in the order they are embedded
-            if ( ! $sorted) {
+            if (! $sorted) {
                 if (CollectionHelper::isHash($mapping['strategy'])) {
                     $collection->set($key, $reference);
                 } else {
@@ -746,9 +759,9 @@ private function loadReferenceManyCollectionOwningSide(PersistentCollectionInter
             $class = $this->dm->getClassMetadata($className);
             $mongoCollection = $this->dm->getDocumentCollection($className);
             $criteria = $this->cm->merge(
-                array('_id' => array('$in' => array_values($ids))),
+                ['_id' => ['$in' => array_values($ids)]],
                 $this->dm->getFilterCollection()->getFilterCriteria($class),
-                $mapping['criteria'] ?? array()
+                $mapping['criteria'] ?? []
             );
             $criteria = $this->uow->getDocumentPersister($className)->prepareQueryOrNewObj($criteria);
 
@@ -762,7 +775,7 @@ private function loadReferenceManyCollectionOwningSide(PersistentCollectionInter
             if (isset($mapping['skip'])) {
                 $options['skip'] = $mapping['skip'];
             }
-            if ( ! empty($hints[Query::HINT_READ_PREFERENCE])) {
+            if (! empty($hints[Query::HINT_READ_PREFERENCE])) {
                 $options['readPreference'] = $hints[Query::HINT_READ_PREFERENCE];
             }
 
@@ -792,7 +805,6 @@ private function loadReferenceManyCollectionInverseSide(PersistentCollectionInte
     }
 
     /**
-     * @param PersistentCollectionInterface $collection
      *
      * @return Query
      */
@@ -803,13 +815,13 @@ public function createReferenceManyInverseSideQuery(PersistentCollectionInterfac
         $owner = $collection->getOwner();
         $ownerClass = $this->dm->getClassMetadata(get_class($owner));
         $targetClass = $this->dm->getClassMetadata($mapping['targetDocument']);
-        $mappedByMapping = $targetClass->fieldMappings[$mapping['mappedBy']] ?? array();
+        $mappedByMapping = $targetClass->fieldMappings[$mapping['mappedBy']] ?? [];
         $mappedByFieldName = ClassMetadata::getReferenceFieldName($mappedByMapping['storeAs'] ?? ClassMetadata::REFERENCE_STORE_AS_DB_REF, $mapping['mappedBy']);
 
         $criteria = $this->cm->merge(
-            array($mappedByFieldName => $ownerClass->getIdentifierObject($owner)),
+            [$mappedByFieldName => $ownerClass->getIdentifierObject($owner)],
             $this->dm->getFilterCollection()->getFilterCriteria($targetClass),
-            $mapping['criteria'] ?? array()
+            $mapping['criteria'] ?? []
         );
         $criteria = $this->uow->getDocumentPersister($mapping['targetDocument'])->prepareQueryOrNewObj($criteria);
         $qb = $this->dm->createQueryBuilder($mapping['targetDocument'])
@@ -825,7 +837,7 @@ public function createReferenceManyInverseSideQuery(PersistentCollectionInterfac
             $qb->skip($mapping['skip']);
         }
 
-        if ( ! empty($hints[Query::HINT_READ_PREFERENCE])) {
+        if (! empty($hints[Query::HINT_READ_PREFERENCE])) {
             $qb->setReadPreference($hints[Query::HINT_READ_PREFERENCE]);
         }
 
@@ -851,7 +863,6 @@ private function loadReferenceManyWithRepositoryMethod(PersistentCollectionInter
     }
 
     /**
-     * @param PersistentCollectionInterface $collection
      *
      * @return \Iterator
      */
@@ -862,11 +873,11 @@ public function createReferenceManyWithRepositoryMethodCursor(PersistentCollecti
         $cursor = $this->dm->getRepository($mapping['targetDocument'])
             ->$repositoryMethod($collection->getOwner());
 
-        if ( ! $cursor instanceof Iterator) {
+        if (! $cursor instanceof Iterator) {
             throw new \BadMethodCallException("Expected repository method {$repositoryMethod} to return an iterable object");
         }
 
-        if (!empty($mapping['prime'])) {
+        if (! empty($mapping['prime'])) {
             $referencePrimer = new ReferencePrimer($this->dm, $this->dm->getUnitOfWork());
             $primers = array_combine($mapping['prime'], array_fill(0, count($mapping['prime']), true));
             $class = $this->dm->getClassMetadata($mapping['targetDocument']);
@@ -886,7 +897,7 @@ public function createReferenceManyWithRepositoryMethodCursor(PersistentCollecti
      */
     public function prepareProjection(array $fields)
     {
-        $preparedFields = array();
+        $preparedFields = [];
 
         foreach ($fields as $key => $value) {
             $preparedFields[$this->prepareFieldName($key)] = $value;
@@ -901,7 +912,7 @@ public function prepareProjection(array $fields)
      */
     private function getSortDirection($sort)
     {
-        switch (strtolower($sort)) {
+        switch (strtolower((string) $sort)) {
             case 'desc':
                 return -1;
 
@@ -963,7 +974,7 @@ public function addDiscriminatorToPreparedQuery(array $preparedQuery)
             if (count($discriminatorValues) === 1) {
                 $preparedQuery[$this->class->discriminatorField] = $discriminatorValues[0];
             } else {
-                $preparedQuery[$this->class->discriminatorField] = array('$in' => $discriminatorValues);
+                $preparedQuery[$this->class->discriminatorField] = ['$in' => $discriminatorValues];
             }
         }
 
@@ -1001,16 +1012,16 @@ public function addFilterToPreparedQuery(array $preparedQuery)
      * PHP field names and types will be converted to those used by MongoDB.
      *
      * @param array $query
-     * @param bool $isNewObj
+     * @param bool  $isNewObj
      * @return array
      */
     public function prepareQueryOrNewObj(array $query, $isNewObj = false)
     {
-        $preparedQuery = array();
+        $preparedQuery = [];
 
         foreach ($query as $key => $value) {
             // Recursively prepare logical query clauses
-            if (in_array($key, array('$and', '$or', '$nor')) && is_array($value)) {
+            if (in_array($key, ['$and', '$or', '$nor']) && is_array($value)) {
                 foreach ($value as $k2 => $v2) {
                     $preparedQuery[$key][$k2] = $this->prepareQueryOrNewObj($v2, $isNewObj);
                 }
@@ -1022,7 +1033,7 @@ public function prepareQueryOrNewObj(array $query, $isNewObj = false)
                 continue;
             }
 
-            $preparedQueryElements = $this->prepareQueryElement($key, $value, null, true, $isNewObj);
+            $preparedQueryElements = $this->prepareQueryElement((string) $key, $value, null, true, $isNewObj);
             foreach ($preparedQueryElements as list($preparedKey, $preparedValue)) {
                 $preparedQuery[$preparedKey] = is_array($preparedValue)
                     ? array_map('\Doctrine\ODM\MongoDB\Types\Type::convertPHPToDatabaseValue', $preparedValue)
@@ -1039,11 +1050,11 @@ public function prepareQueryOrNewObj(array $query, $isNewObj = false)
      *
      * It also handles converting $fieldName to the database name if they are different.
      *
-     * @param string $fieldName
-     * @param mixed $value
+     * @param string        $fieldName
+     * @param mixed         $value
      * @param ClassMetadata $class        Defaults to $this->class
-     * @param bool $prepareValue Whether or not to prepare the value
-     * @param bool $inNewObj Whether or not newObj is being prepared
+     * @param bool          $prepareValue Whether or not to prepare the value
+     * @param bool          $inNewObj     Whether or not newObj is being prepared
      * @return array An array of tuples containing prepared field names and values
      */
     private function prepareQueryElement($fieldName, $value = null, $class = null, $prepareValue = true, $inNewObj = false)
@@ -1057,17 +1068,17 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
             $mapping = $class->fieldMappings[$fieldName];
             $fieldName = $mapping['name'];
 
-            if ( ! $prepareValue) {
+            if (! $prepareValue) {
                 return [[$fieldName, $value]];
             }
 
             // Prepare mapped, embedded objects
-            if ( ! empty($mapping['embedded']) && is_object($value) &&
+            if (! empty($mapping['embedded']) && is_object($value) &&
                 ! $this->dm->getMetadataFactory()->isTransient(get_class($value))) {
                 return [[$fieldName, $this->pb->prepareEmbeddedDocumentValue($mapping, $value)]];
             }
 
-            if (! empty($mapping['reference']) && is_object($value) && ! ($value instanceof \MongoDB\BSON\ObjectId)) {
+            if (! empty($mapping['reference']) && is_object($value) && ! ($value instanceof ObjectId)) {
                 try {
                     return $this->prepareReference($fieldName, $value, $mapping, $inNewObj);
                 } catch (MappingException $e) {
@@ -1085,12 +1096,12 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
             // Additional preparation for one or more simple reference values
             $targetClass = $this->dm->getClassMetadata($mapping['targetDocument']);
 
-            if ( ! is_array($value)) {
+            if (! is_array($value)) {
                 return [[$fieldName, $targetClass->getDatabaseIdentifierValue($value)]];
             }
 
             // Objects without operators or with DBRef fields can be converted immediately
-            if ( ! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
+            if (! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
                 return [[$fieldName, $targetClass->getDatabaseIdentifierValue($value)]];
             }
 
@@ -1101,16 +1112,16 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
         if (($class->hasField($fieldName) && $class->isIdentifier($fieldName)) || $fieldName === '_id') {
             $fieldName = '_id';
 
-            if ( ! $prepareValue) {
+            if (! $prepareValue) {
                 return [[$fieldName, $value]];
             }
 
-            if ( ! is_array($value)) {
+            if (! is_array($value)) {
                 return [[$fieldName, $class->getDatabaseIdentifierValue($value)]];
             }
 
             // Objects without operators or with DBRef fields can be converted immediately
-            if ( ! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
+            if (! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
                 return [[$fieldName, $class->getDatabaseIdentifierValue($value)]];
             }
 
@@ -1131,7 +1142,7 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
         $e = explode('.', $fieldName, 4);
 
         // No further processing for unmapped fields
-        if ( ! isset($class->fieldMappings[$e[0]])) {
+        if (! isset($class->fieldMappings[$e[0]])) {
             return [[$fieldName, $value]];
         }
 
@@ -1145,12 +1156,12 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
             return [[$fieldName, $value]];
         }
 
-        if ($mapping['type'] == 'many' && CollectionHelper::isHash($mapping['strategy'])
+        if ($mapping['type'] === 'many' && CollectionHelper::isHash($mapping['strategy'])
                 && isset($e[2])) {
             $objectProperty = $e[2];
             $objectPropertyPrefix = $e[1] . '.';
             $nextObjectProperty = implode('.', array_slice($e, 3));
-        } elseif ($e[1] != '$') {
+        } elseif ($e[1] !== '$') {
             $fieldName = $e[0] . '.' . $e[1];
             $objectProperty = $e[1];
             $objectPropertyPrefix = '';
@@ -1167,9 +1178,9 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
         }
 
         // No further processing for fields without a targetDocument mapping
-        if ( ! isset($mapping['targetDocument'])) {
+        if (! isset($mapping['targetDocument'])) {
             if ($nextObjectProperty) {
-                $fieldName .= '.'.$nextObjectProperty;
+                $fieldName .= '.' . $nextObjectProperty;
             }
 
             return [[$fieldName, $value]];
@@ -1178,9 +1189,9 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
         $targetClass = $this->dm->getClassMetadata($mapping['targetDocument']);
 
         // No further processing for unmapped targetDocument fields
-        if ( ! $targetClass->hasField($objectProperty)) {
+        if (! $targetClass->hasField($objectProperty)) {
             if ($nextObjectProperty) {
-                $fieldName .= '.'.$nextObjectProperty;
+                $fieldName .= '.' . $nextObjectProperty;
             }
 
             return [[$fieldName, $value]];
@@ -1196,16 +1207,16 @@ private function prepareQueryElement($fieldName, $value = null, $class = null, $
 
         // Process targetDocument identifier fields
         if ($objectPropertyIsId) {
-            if ( ! $prepareValue) {
+            if (! $prepareValue) {
                 return [[$fieldName, $value]];
             }
 
-            if ( ! is_array($value)) {
+            if (! is_array($value)) {
                 return [[$fieldName, $targetClass->getDatabaseIdentifierValue($value)]];
             }
 
             // Objects without operators or with DBRef fields can be converted immediately
-            if ( ! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
+            if (! $this->hasQueryOperators($value) || $this->hasDBRefFields($value)) {
                 return [[$fieldName, $targetClass->getDatabaseIdentifierValue($value)]];
             }
 
@@ -1245,12 +1256,12 @@ private function prepareQueryExpression($expression, $class)
     {
         foreach ($expression as $k => $v) {
             // Ignore query operators whose arguments need no type conversion
-            if (in_array($k, array('$exists', '$type', '$mod', '$size'))) {
+            if (in_array($k, ['$exists', '$type', '$mod', '$size'])) {
                 continue;
             }
 
             // Process query operators whose argument arrays need type conversion
-            if (in_array($k, array('$in', '$nin', '$all')) && is_array($v)) {
+            if (in_array($k, ['$in', '$nin', '$all']) && is_array($v)) {
                 foreach ($v as $k2 => $v2) {
                     $expression[$k][$k2] = $class->getDatabaseIdentifierValue($v2);
                 }
@@ -1278,11 +1289,11 @@ private function prepareQueryExpression($expression, $class)
      * $elemMatch criteria for matching a DBRef.
      *
      * @param mixed $value
-     * @return boolean
+     * @return bool
      */
     private function hasDBRefFields($value)
     {
-        if ( ! is_array($value) && ! is_object($value)) {
+        if (! is_array($value) && ! is_object($value)) {
             return false;
         }
 
@@ -1303,11 +1314,11 @@ private function hasDBRefFields($value)
      * Checks whether the value has query operators.
      *
      * @param mixed $value
-     * @return boolean
+     * @return bool
      */
     private function hasQueryOperators($value)
     {
-        if ( ! is_array($value) && ! is_object($value)) {
+        if (! is_array($value) && ! is_object($value)) {
             return false;
         }
 
@@ -1327,12 +1338,11 @@ private function hasQueryOperators($value)
     /**
      * Gets the array of discriminator values for the given ClassMetadata
      *
-     * @param ClassMetadata $metadata
      * @return array
      */
     private function getClassDiscriminatorValues(ClassMetadata $metadata)
     {
-        $discriminatorValues = array($metadata->discriminatorValue);
+        $discriminatorValues = [$metadata->discriminatorValue];
         foreach ($metadata->subClasses as $className) {
             if ($key = array_search($className, $metadata->discriminatorMap)) {
                 $discriminatorValues[] = $key;
@@ -1385,11 +1395,11 @@ private function guardMissingShardKey($document, $shardKeyField, $actualDocument
         $fieldMapping = $this->class->getFieldMappingByDbFieldName($shardKeyField);
         $fieldName = $fieldMapping['fieldName'];
 
-        if ($isUpdate && isset($dcs[$fieldName]) && $dcs[$fieldName][0] != $dcs[$fieldName][1]) {
+        if ($isUpdate && isset($dcs[$fieldName]) && $dcs[$fieldName][0] !== $dcs[$fieldName][1]) {
             throw MongoDBException::shardKeyFieldCannotBeChanged($shardKeyField, $this->class->getName());
         }
 
-        if (!isset($actualDocumentData[$fieldName])) {
+        if (! isset($actualDocumentData[$fieldName])) {
             throw MongoDBException::shardKeyFieldMissing($shardKeyField, $this->class->getName());
         }
     }
@@ -1407,7 +1417,7 @@ private function getQueryForDocument($document)
         $id = $this->class->getDatabaseIdentifierValue($id);
 
         $shardKeyQueryPart = $this->getShardKeyQuery($document);
-        $query = array_merge(array('_id' => $id), $shardKeyQueryPart);
+        $query = array_merge(['_id' => $id], $shardKeyQueryPart);
 
         return $query;
     }
@@ -1417,7 +1427,7 @@ private function getQueryForDocument($document)
      *
      * @return array
      */
-    private function getWriteOptions(array $options = array())
+    private function getWriteOptions(array $options = [])
     {
         $defaultOptions = $this->dm->getConfiguration()->getDefaultCommitOptions();
         $documentOptions = [];
@@ -1430,9 +1440,9 @@ private function getWriteOptions(array $options = array())
 
     /**
      * @param string $fieldName
-     * @param mixed $value
-     * @param array $mapping
-     * @param bool $inNewObj
+     * @param mixed  $value
+     * @param array  $mapping
+     * @param bool   $inNewObj
      * @return array
      */
     private function prepareReference($fieldName, $value, array $mapping, $inNewObj)
@@ -1451,7 +1461,7 @@ private function prepareReference($fieldName, $value, array $mapping, $inNewObj)
             case ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB:
                 $keys = ['$ref' => true, '$id' => true, '$db' => true];
 
-            if ($mapping['storeAs'] === ClassMetadata::REFERENCE_STORE_AS_DB_REF) {
+                if ($mapping['storeAs'] === ClassMetadata::REFERENCE_STORE_AS_DB_REF) {
                     unset($keys['$db']);
                 }
 
diff --git a/lib/Doctrine/ODM/MongoDB/Persisters/PersistenceBuilder.php b/lib/Doctrine/ODM/MongoDB/Persisters/PersistenceBuilder.php
index 0b9368cc75..0dbd45ad70 100644
--- a/lib/Doctrine/ODM/MongoDB/Persisters/PersistenceBuilder.php
+++ b/lib/Doctrine/ODM/MongoDB/Persisters/PersistenceBuilder.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Persisters;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -7,13 +10,16 @@
 use Doctrine\ODM\MongoDB\Types\Type;
 use Doctrine\ODM\MongoDB\UnitOfWork;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
+use function array_search;
+use function array_values;
+use function get_class;
+use function is_null;
 
 /**
  * PersistenceBuilder builds the queries used by the persisters to update and insert
  * documents when a DocumentManager is flushed. It uses the changeset information in the
  * UnitOfWork to build queries using atomic operators like $set, $unset, etc.
  *
- * @since       1.0
  */
 class PersistenceBuilder
 {
@@ -34,8 +40,6 @@ class PersistenceBuilder
     /**
      * Initializes a new PersistenceBuilder instance.
      *
-     * @param DocumentManager $dm
-     * @param UnitOfWork $uow
      */
     public function __construct(DocumentManager $dm, UnitOfWork $uow)
     {
@@ -54,9 +58,8 @@ public function prepareInsertData($document)
         $class = $this->dm->getClassMetadata(get_class($document));
         $changeset = $this->uow->getDocumentChangeSet($document);
 
-        $insertData = array();
+        $insertData = [];
         foreach ($class->fieldMappings as $mapping) {
-
             $new = $changeset[$mapping['fieldName']][1] ?? null;
 
             if ($new === null && $mapping['nullable']) {
@@ -71,7 +74,7 @@ public function prepareInsertData($document)
             }
 
             // @Field, @String, @Date, etc.
-            if ( ! isset($mapping['association'])) {
+            if (! isset($mapping['association'])) {
                 $insertData[$mapping['name']] = Type::getType($mapping['type'])->convertToDatabaseValue($new);
 
             // @ReferenceOne
@@ -110,19 +113,19 @@ public function prepareUpdateData($document)
         $class = $this->dm->getClassMetadata(get_class($document));
         $changeset = $this->uow->getDocumentChangeSet($document);
 
-        $updateData = array();
+        $updateData = [];
         foreach ($changeset as $fieldName => $change) {
             $mapping = $class->fieldMappings[$fieldName];
 
             // skip non embedded document identifiers
-            if ( ! $class->isEmbeddedDocument && ! empty($mapping['id'])) {
+            if (! $class->isEmbeddedDocument && ! empty($mapping['id'])) {
                 continue;
             }
 
             list($old, $new) = $change;
 
             // Scalar fields
-            if ( ! isset($mapping['association'])) {
+            if (! isset($mapping['association'])) {
                 if ($new === null && $mapping['nullable'] !== true) {
                     $updateData['$unset'][$mapping['name']] = true;
                 } else {
@@ -144,7 +147,7 @@ public function prepareUpdateData($document)
                     $updateData['$set'][$mapping['name']] = $this->prepareEmbeddedDocumentValue($mapping, $new);
 
                 // If we don't have a new value then lets unset the embedded document
-                } elseif ( ! $new) {
+                } elseif (! $new) {
                     $updateData['$unset'][$mapping['name']] = true;
 
                 // Update existing embedded document
@@ -169,7 +172,7 @@ public function prepareUpdateData($document)
                     $this->uow->unscheduleCollectionDeletion($old);
                 } elseif ($mapping['association'] === ClassMetadata::EMBED_MANY) {
                     foreach ($new as $key => $embeddedDoc) {
-                        if ( ! $this->uow->isScheduledForInsert($embeddedDoc)) {
+                        if (! $this->uow->isScheduledForInsert($embeddedDoc)) {
                             $update = $this->prepareUpdateData($embeddedDoc);
                             foreach ($update as $cmd => $values) {
                                 foreach ($values as $name => $value) {
@@ -215,14 +218,14 @@ public function prepareUpsertData($document)
         $class = $this->dm->getClassMetadata(get_class($document));
         $changeset = $this->uow->getDocumentChangeSet($document);
 
-        $updateData = array();
+        $updateData = [];
         foreach ($changeset as $fieldName => $change) {
             $mapping = $class->fieldMappings[$fieldName];
 
             list($old, $new) = $change;
 
             // Scalar fields
-            if ( ! isset($mapping['association'])) {
+            if (! isset($mapping['association'])) {
                 if ($new !== null || $mapping['nullable'] === true) {
                     if ($new !== null && empty($mapping['id']) && isset($mapping['strategy']) && $mapping['strategy'] === ClassMetadata::STORAGE_STRATEGY_INCREMENT) {
                         $operator = '$inc';
@@ -280,7 +283,7 @@ public function prepareUpsertData($document)
      * If the document does not have an identifier and the mapping calls for a
      * simple reference, null may be returned.
      *
-     * @param array $referenceMapping
+     * @param array  $referenceMapping
      * @param object $document
      * @return array|null
      */
@@ -303,20 +306,20 @@ public function prepareReferencedDocumentValue(array $referenceMapping, $documen
      * within this value were previously scheduled for deletion or update, they
      * will also be unscheduled.
      *
-     * @param array $embeddedMapping
+     * @param array  $embeddedMapping
      * @param object $embeddedDocument
-     * @param boolean $includeNestedCollections
+     * @param bool   $includeNestedCollections
      * @return array|object
      * @throws \UnexpectedValueException if an unsupported associating mapping is found
      */
     public function prepareEmbeddedDocumentValue(array $embeddedMapping, $embeddedDocument, $includeNestedCollections = false)
     {
-        $embeddedDocumentValue = array();
+        $embeddedDocumentValue = [];
         $class = $this->dm->getClassMetadata(get_class($embeddedDocument));
 
         foreach ($class->fieldMappings as $mapping) {
             // Skip notSaved fields
-            if ( ! empty($mapping['notSaved'])) {
+            if (! empty($mapping['notSaved'])) {
                 continue;
             }
 
@@ -341,7 +344,7 @@ public function prepareEmbeddedDocumentValue(array $embeddedMapping, $embeddedDo
                     case ClassMetadata::EMBED_MANY:
                     case ClassMetadata::REFERENCE_MANY:
                         // Skip PersistentCollections already scheduled for deletion
-                        if ( ! $includeNestedCollections && $rawValue instanceof PersistentCollectionInterface
+                        if (! $includeNestedCollections && $rawValue instanceof PersistentCollectionInterface
                             && $this->uow->isCollectionScheduledForDeletion($rawValue)) {
                             break;
                         }
@@ -365,7 +368,7 @@ public function prepareEmbeddedDocumentValue(array $embeddedMapping, $embeddedDo
         /* Add a discriminator value if the embedded document is not mapped
          * explicitly to a targetDocument class.
          */
-        if ( ! isset($embeddedMapping['targetDocument'])) {
+        if (! isset($embeddedMapping['targetDocument'])) {
             $discriminatorField = $embeddedMapping['discriminatorField'];
             $discriminatorValue = isset($embeddedMapping['discriminatorMap'])
                 ? array_search($class->name, $embeddedMapping['discriminatorMap'])
@@ -430,7 +433,6 @@ public function prepareAssociatedDocumentValue(array $mapping, $document, $inclu
     /**
      * Returns the collection representation to be stored and unschedules it afterwards.
      *
-     * @param PersistentCollectionInterface $coll
      * @param bool $includeNestedCollections
      * @return array
      */
@@ -439,10 +441,12 @@ public function prepareAssociatedCollectionValue(PersistentCollectionInterface $
         $mapping = $coll->getMapping();
         $pb = $this;
         $callback = isset($mapping['embedded'])
-            ? function($v) use ($pb, $mapping, $includeNestedCollections) {
+            ? function ($v) use ($pb, $mapping, $includeNestedCollections) {
                 return $pb->prepareEmbeddedDocumentValue($mapping, $v, $includeNestedCollections);
             }
-            : function($v) use ($pb, $mapping) { return $pb->prepareReferencedDocumentValue($mapping, $v); };
+            : function ($v) use ($pb, $mapping) {
+                return $pb->prepareReferencedDocumentValue($mapping, $v);
+            };
 
         $setData = $coll->map($callback)->toArray();
         if (CollectionHelper::isList($mapping['strategy'])) {
diff --git a/lib/Doctrine/ODM/MongoDB/Proxy/Proxy.php b/lib/Doctrine/ODM/MongoDB/Proxy/Proxy.php
index 88e970434a..994872b847 100644
--- a/lib/Doctrine/ODM/MongoDB/Proxy/Proxy.php
+++ b/lib/Doctrine/ODM/MongoDB/Proxy/Proxy.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Proxy;
 
 use Doctrine\Common\Proxy\Proxy as BaseProxy;
@@ -7,6 +9,7 @@
 /**
  * Document Proxy interface.
  *
- * @since       1.0
  */
-interface Proxy extends BaseProxy {}
+interface Proxy extends BaseProxy
+{
+}
diff --git a/lib/Doctrine/ODM/MongoDB/Proxy/ProxyFactory.php b/lib/Doctrine/ODM/MongoDB/Proxy/ProxyFactory.php
index e6b330511b..6dfb52d57c 100644
--- a/lib/Doctrine/ODM/MongoDB/Proxy/ProxyFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Proxy/ProxyFactory.php
@@ -1,34 +1,39 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Proxy;
 
+use Doctrine\Common\EventManager;
 use Doctrine\Common\NotifyPropertyChanged;
+use Doctrine\Common\Persistence\Mapping\ClassMetadata as BaseClassMetadata;
 use Doctrine\Common\Proxy\AbstractProxyFactory;
+use Doctrine\Common\Proxy\Proxy as BaseProxy;
 use Doctrine\Common\Proxy\ProxyDefinition;
-use Doctrine\ODM\MongoDB\DocumentManager;
-use Doctrine\ODM\MongoDB\DocumentNotFoundException;
 use Doctrine\Common\Proxy\ProxyGenerator;
 use Doctrine\Common\Util\ClassUtils;
-use Doctrine\Common\Proxy\Proxy as BaseProxy;
-use Doctrine\Common\Persistence\Mapping\ClassMetadata as BaseClassMetadata;
+use Doctrine\ODM\MongoDB\DocumentManager;
+use Doctrine\ODM\MongoDB\DocumentNotFoundException;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
+use Doctrine\ODM\MongoDB\UnitOfWork;
 use Doctrine\ODM\MongoDB\Utility\LifecycleEventManager;
 use ReflectionProperty;
+use function get_class;
 
 /**
  * This factory is used to create proxy objects for documents at runtime.
  *
- * @since       1.0
  */
 class ProxyFactory extends AbstractProxyFactory
 {
     /**
-     * @var \Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory
+     * @var ClassMetadataFactory
      */
     private $metadataFactory;
 
     /**
-     * @var \Doctrine\ODM\MongoDB\UnitOfWork The UnitOfWork this factory is bound to.
+     * @var UnitOfWork The UnitOfWork this factory is bound to.
      */
     private $uow;
 
@@ -38,7 +43,7 @@ class ProxyFactory extends AbstractProxyFactory
     private $proxyNamespace;
 
     /**
-     * @var \Doctrine\Common\EventManager
+     * @var EventManager
      */
     private $lifecycleEventManager;
 
@@ -46,11 +51,11 @@ class ProxyFactory extends AbstractProxyFactory
      * Initializes a new instance of the <tt>ProxyFactory</tt> class that is
      * connected to the given <tt>DocumentManager</tt>.
      *
-     * @param \Doctrine\ODM\MongoDB\DocumentManager $documentManager The DocumentManager the new factory works for.
-     * @param string                                $proxyDir        The directory to use for the proxy classes. It
-     *                                                               must exist.
-     * @param string                                $proxyNamespace  The namespace to use for the proxy classes.
-     * @param integer                               $autoGenerate    Whether to automatically generate proxy classes.
+     * @param DocumentManager $documentManager The DocumentManager the new factory works for.
+     * @param string          $proxyDir        The directory to use for the proxy classes. It
+     *                                         must exist.
+     * @param string          $proxyNamespace  The namespace to use for the proxy classes.
+     * @param int             $autoGenerate    Whether to automatically generate proxy classes.
      */
     public function __construct(DocumentManager $documentManager, $proxyDir, $proxyNamespace, $autoGenerate = AbstractProxyFactory::AUTOGENERATE_NEVER)
     {
@@ -96,13 +101,10 @@ public function createProxyDefinition($className)
     /**
      * Generates a closure capable of initializing a proxy
      *
-     * @param \Doctrine\Common\Persistence\Mapping\ClassMetadata $classMetadata
-     * @param \Doctrine\ODM\MongoDB\Persisters\DocumentPersister $documentPersister
-     * @param \ReflectionProperty                                $reflectionId
      *
      * @return \Closure
      *
-     * @throws \Doctrine\ODM\MongoDB\DocumentNotFoundException
+     * @throws DocumentNotFoundException
      */
     private function createInitializer(
         BaseClassMetadata $classMetadata,
@@ -121,7 +123,7 @@ private function createInitializer(
                 $properties = $proxy->__getLazyProperties();
 
                 foreach ($properties as $propertyName => $property) {
-                    if ( ! isset($proxy->$propertyName)) {
+                    if (! isset($proxy->$propertyName)) {
                         $proxy->$propertyName = $properties[$propertyName];
                     }
                 }
@@ -131,8 +133,8 @@ private function createInitializer(
 
                 $id = $reflectionId->getValue($proxy);
 
-                if (null === $documentPersister->load(array('_id' => $id), $proxy)) {
-                    if ( ! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
+                if ($documentPersister->load(['_id' => $id], $proxy) === null) {
+                    if (! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
                         throw DocumentNotFoundException::documentNotFound(get_class($proxy), $id);
                     }
                 }
@@ -154,7 +156,7 @@ private function createInitializer(
             $properties = $proxy->__getLazyProperties();
 
             foreach ($properties as $propertyName => $property) {
-                if ( ! isset($proxy->$propertyName)) {
+                if (! isset($proxy->$propertyName)) {
                     $proxy->$propertyName = $properties[$propertyName];
                 }
             }
@@ -163,8 +165,8 @@ private function createInitializer(
 
             $id = $reflectionId->getValue($proxy);
 
-            if (null === $documentPersister->load(array('_id' => $id), $proxy)) {
-                if ( ! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
+            if ($documentPersister->load(['_id' => $id], $proxy) === null) {
+                if (! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
                     throw DocumentNotFoundException::documentNotFound(get_class($proxy), $id);
                 }
             }
@@ -178,13 +180,10 @@ private function createInitializer(
     /**
      * Generates a closure capable of finalizing a cloned proxy
      *
-     * @param \Doctrine\Common\Persistence\Mapping\ClassMetadata $classMetadata
-     * @param \Doctrine\ODM\MongoDB\Persisters\DocumentPersister $documentPersister
-     * @param \ReflectionProperty                                $reflectionId
      *
      * @return \Closure
      *
-     * @throws \Doctrine\ODM\MongoDB\DocumentNotFoundException
+     * @throws DocumentNotFoundException
      */
     private function createCloner(
         BaseClassMetadata $classMetadata,
@@ -200,10 +199,10 @@ private function createCloner(
             $proxy->__setInitializer(null);
 
             $id       = $reflectionId->getValue($proxy);
-            $original = $documentPersister->load(array('_id' => $id));
+            $original = $documentPersister->load(['_id' => $id]);
 
-            if (null === $original) {
-                if ( ! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
+            if ($original === null) {
+                if (! $this->lifecycleEventManager->documentNotFound($proxy, $id)) {
                     throw DocumentNotFoundException::documentNotFound(get_class($proxy), $id);
                 }
             }
diff --git a/lib/Doctrine/ODM/MongoDB/Query/Builder.php b/lib/Doctrine/ODM/MongoDB/Query/Builder.php
index 8af027e822..104c03e59e 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/Builder.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/Builder.php
@@ -1,18 +1,31 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use GeoJson\Geometry\Geometry;
 use GeoJson\Geometry\Point;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\Javascript;
 use MongoDB\Collection;
 use MongoDB\Driver\ReadPreference;
+use function array_filter;
+use function array_key_exists;
+use function array_search;
+use function count;
+use function func_get_args;
+use function is_array;
+use function is_bool;
+use function is_callable;
+use function is_string;
+use function strtolower;
 
 /**
  * Query builder for ODM.
  *
- * @since       1.0
  */
 class Builder
 {
@@ -26,7 +39,7 @@ class Builder
     /**
      * The ClassMetadata instance.
      *
-     * @var \Doctrine\ODM\MongoDB\Mapping\ClassMetadata
+     * @var ClassMetadata
      */
     private $class;
 
@@ -41,14 +54,14 @@ class Builder
     /**
      * Whether or not to hydrate the data to documents.
      *
-     * @var boolean
+     * @var bool
      */
     private $hydrate = true;
 
     /**
      * Whether or not to refresh the data for documents that are already in the identity map.
      *
-     * @var boolean
+     * @var bool
      */
     private $refresh = false;
 
@@ -57,7 +70,7 @@ class Builder
      *
      * @var array
      */
-    private $primers = array();
+    private $primers = [];
 
     /**
      * Whether or not to register documents in UnitOfWork.
@@ -93,7 +106,6 @@ class Builder
     /**
      * Construct a Builder
      *
-     * @param DocumentManager $dm
      * @param string[]|string|null $documentName (optional) an array of document names, the document name, or none
      */
     public function __construct(DocumentManager $dm, $documentName = null)
@@ -232,7 +244,7 @@ public function bitOr($value)
      *
      * @see Expr::bitsAllClear()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAllClear/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAllClear($value)
@@ -247,7 +259,7 @@ public function bitsAllClear($value)
      *
      * @see Expr::bitsAllSet()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAllSet/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAllSet($value)
@@ -262,7 +274,7 @@ public function bitsAllSet($value)
      *
      * @see Expr::bitsAnyClear()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAnyClear/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAnyClear($value)
@@ -277,7 +289,7 @@ public function bitsAnyClear($value)
      *
      * @see Expr::bitsAnySet()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAnySet/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAnySet($value)
@@ -312,7 +324,6 @@ public function bitXor($value)
      * @return $this
      * @throws \BadMethodCallException if the query does not already have $text criteria
      *
-     * @since 1.3
      */
     public function caseSensitive($caseSensitive)
     {
@@ -386,7 +397,6 @@ public function debug($name = null)
      * @return $this
      * @throws \BadMethodCallException if the query does not already have $text criteria
      *
-     * @since 1.3
      */
     public function diacriticSensitive($diacriticSensitive)
     {
@@ -411,16 +421,16 @@ public function distinct($field)
     /**
      * Set whether the query should return its result as an EagerCursor.
      *
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function eagerCursor($bool = true)
     {
-        if ( ! $bool && ! empty($this->primers)) {
+        if (! $bool && ! empty($this->primers)) {
             throw new \BadMethodCallException("Can't set eagerCursor to false when using reference primers");
         }
 
-        $this->query['eagerCursor'] = (boolean) $bool;
+        $this->query['eagerCursor'] = (bool) $bool;
         return $this;
     }
 
@@ -464,7 +474,7 @@ public function equals($value)
      */
     public function exclude($fieldName = null)
     {
-        if ( ! isset($this->query['select'])) {
+        if (! isset($this->query['select'])) {
             $this->query['select'] = [];
         }
 
@@ -482,12 +492,12 @@ public function exclude($fieldName = null)
      *
      * @see Expr::exists()
      * @see http://docs.mongodb.org/manual/reference/operator/exists/
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function exists($bool)
     {
-        $this->expr->exists((boolean) $bool);
+        $this->expr->exists((bool) $bool);
         return $this;
     }
 
@@ -521,7 +531,7 @@ public function field($field)
     /**
      * Set the "finalize" option for a mapReduce or group command.
      *
-     * @param string|\MongoDB\BSON\Javascript $finalize
+     * @param string|Javascript $finalize
      * @return $this
      * @throws \BadMethodCallException if the query is not a mapReduce or group command
      */
@@ -688,9 +698,9 @@ public function geoWithinCenterSphere($x, $y, $radius)
      *
      * @see Expr::geoWithinPolygon()
      * @see http://docs.mongodb.org/manual/reference/operator/polygon/
-     * @param array $point1 First point of the polygon
-     * @param array $point2 Second point of the polygon
-     * @param array $point3 Third point of the polygon
+     * @param array $point1    First point of the polygon
+     * @param array $point2    Second point of the polygon
+     * @param array $point3    Third point of the polygon
      * @param array ...$points Additional points of the polygon
      * @return $this
      */
@@ -717,7 +727,7 @@ public function getNewObj()
      * @param array $options
      * @return Query $query
      */
-    public function getQuery(array $options = array())
+    public function getQuery(array $options = [])
     {
         if ($this->query['type'] === Query::TYPE_MAP_REDUCE) {
             $this->hydrate = false;
@@ -743,11 +753,13 @@ public function getQuery(array $options = array())
                 'discriminator. Either not use base class or set \'' . $this->class->discriminatorField . '\' field manually.');
         }
 
-        if ( ! empty($query['select'])) {
+        if (! empty($query['select'])) {
             $query['select'] = $documentPersister->prepareProjection($query['select']);
             if ($this->hydrate && $this->class->inheritanceType === ClassMetadata::INHERITANCE_TYPE_SINGLE_COLLECTION
                 && ! isset($query['select'][$this->class->discriminatorField])) {
-                $includeMode = 0 < count(array_filter($query['select'], function($mode) { return $mode == 1; }));
+                $includeMode = 0 < count(array_filter($query['select'], function ($mode) {
+                    return $mode === 1;
+                }));
                 if ($includeMode && ! isset($query['select'][$this->class->discriminatorField])) {
                     $query['select'][$this->class->discriminatorField] = 1;
                 }
@@ -789,7 +801,7 @@ public function getQueryArray()
     /**
      * Get the type of this query.
      *
-     * @return integer $type
+     * @return int $type
      */
     public function getType()
     {
@@ -849,12 +861,12 @@ public function hydrate($bool = true)
     /**
      * Set the immortal cursor flag.
      *
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function immortal($bool = true)
     {
-        $this->query['immortal'] = (boolean) $bool;
+        $this->query['immortal'] = (bool) $bool;
         return $this;
     }
 
@@ -879,7 +891,7 @@ public function in(array $values)
      *
      * @see Expr::inc()
      * @see http://docs.mongodb.org/manual/reference/operator/inc/
-     * @param float|integer $value
+     * @param float|int $value
      * @return $this
      */
     public function inc($value)
@@ -933,12 +945,12 @@ public function language($language)
      * commands.
      *
      * @see Query::prepareCursor()
-     * @param integer $limit
+     * @param int $limit
      * @return $this
      */
     public function limit($limit)
     {
-        $this->query['limit'] = (integer) $limit;
+        $this->query['limit'] = (int) $limit;
         return $this;
     }
 
@@ -979,7 +991,7 @@ public function lte($value)
      * The "out" option defaults to inline, like {@link Builder::mapReduce()}.
      *
      * @see http://docs.mongodb.org/manual/reference/command/mapReduce/
-     * @param string|\MongoDB\BSON\Javascript $map
+     * @param string|Javascript $map
      * @return $this
      */
     public function map($map)
@@ -998,10 +1010,10 @@ public function map($map)
      * Change the query type to a mapReduce command.
      *
      * @see http://docs.mongodb.org/manual/reference/command/mapReduce/
-     * @param string|\MongoDB\BSON\Javascript $map
-     * @param string|\MongoDB\BSON\Javascript $reduce
-     * @param array|string $out
-     * @param array $options
+     * @param string|Javascript $map
+     * @param string|Javascript $reduce
+     * @param array|string      $out
+     * @param array             $options
      * @return $this
      */
     public function mapReduce($map, $reduce, $out = ['inline' => true], array $options = [])
@@ -1011,7 +1023,7 @@ public function mapReduce($map, $reduce, $out = ['inline' => true], array $optio
             'map' => $map,
             'reduce' => $reduce,
             'out' => $out,
-            'options' => $options
+            'options' => $options,
         ];
         return $this;
     }
@@ -1078,8 +1090,8 @@ public function min($value)
      *
      * @see Expr::mod()
      * @see http://docs.mongodb.org/manual/reference/operator/mod/
-     * @param float|integer $divisor
-     * @param float|integer $remainder
+     * @param float|int $divisor
+     * @param float|int $remainder
      * @return $this
      */
     public function mod($divisor, $remainder = 0)
@@ -1095,7 +1107,7 @@ public function mod($divisor, $remainder = 0)
      *
      * @see Expr::mul()
      * @see http://docs.mongodb.org/manual/reference/operator/mul/
-     * @param float|integer $value
+     * @param float|int $value
      * @return $this
      */
     public function mul($value)
@@ -1114,7 +1126,7 @@ public function mul($value)
      * @see Expr::near()
      * @see http://docs.mongodb.org/manual/reference/operator/near/
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return $this
      */
     public function near($x, $y = null)
@@ -1133,7 +1145,7 @@ public function near($x, $y = null)
      * @see Expr::nearSphere()
      * @see http://docs.mongodb.org/manual/reference/operator/nearSphere/
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return $this
      */
     public function nearSphere($x, $y = null)
@@ -1243,13 +1255,13 @@ public function popLast()
      * If a custom callable is used, its signature should conform to the default
      * Closure defined in {@link ReferencePrimer::__construct()}.
      *
-     * @param boolean|callable $primer
+     * @param bool|callable $primer
      * @return $this
      * @throws \InvalidArgumentException If $primer is not boolean or callable
      */
     public function prime($primer = true)
     {
-        if ( ! is_bool($primer) && ! is_callable($primer)) {
+        if (! is_bool($primer) && ! is_callable($primer)) {
             throw new \InvalidArgumentException('$primer is not a boolean or callable');
         }
 
@@ -1259,7 +1271,7 @@ public function prime($primer = true)
             return $this;
         }
 
-        if (array_key_exists('eagerCursor', $this->query) && !$this->query['eagerCursor']) {
+        if (array_key_exists('eagerCursor', $this->query) && ! $this->query['eagerCursor']) {
             throw new \BadMethodCallException("Can't call prime() when setting eagerCursor to false");
         }
 
@@ -1352,7 +1364,7 @@ public function readOnly($bool = true)
     /**
      * Set the "reduce" option for a mapReduce or group command.
      *
-     * @param string|\MongoDB\BSON\Javascript $reduce
+     * @param string|Javascript $reduce
      * @return $this
      * @throws \BadMethodCallException if the query is not a mapReduce or group command
      */
@@ -1427,7 +1439,7 @@ public function rename($name)
     public function returnNew($bool = true)
     {
         $this->refresh(true);
-        $this->query['new'] = (boolean) $bool;
+        $this->query['new'] = (bool) $bool;
 
         return $this;
     }
@@ -1440,7 +1452,7 @@ public function returnNew($bool = true)
      */
     public function select($fieldName = null)
     {
-        if ( ! isset($this->query['select'])) {
+        if (! isset($this->query['select'])) {
             $this->query['select'] = [];
         }
 
@@ -1458,7 +1470,7 @@ public function select($fieldName = null)
      * projection.
      *
      * @see http://docs.mongodb.org/manual/reference/projection/elemMatch/
-     * @param string $fieldName
+     * @param string     $fieldName
      * @param array|Expr $expression
      * @return $this
      */
@@ -1494,8 +1506,8 @@ public function selectMeta($fieldName, $metaDataKeyword)
      *
      * @see http://docs.mongodb.org/manual/reference/projection/slice/
      * @param string $fieldName
-     * @param integer $countOrSkip Count parameter, or skip if limit is specified
-     * @param integer $limit       Limit parameter used in conjunction with skip
+     * @param int    $countOrSkip Count parameter, or skip if limit is specified
+     * @param int    $limit       Limit parameter used in conjunction with skip
      * @return $this
      */
     public function selectSlice($fieldName, $countOrSkip, $limit = null)
@@ -1518,7 +1530,7 @@ public function selectSlice($fieldName, $countOrSkip, $limit = null)
      * @see Expr::set()
      * @see http://docs.mongodb.org/manual/reference/operator/set/
      * @param mixed $value
-     * @param boolean $atomic
+     * @param bool  $atomic
      * @return $this
      */
     public function set($value, $atomic = true)
@@ -1566,7 +1578,6 @@ public function setOnInsert($value)
      * This is only relevant for read-only queries and commands.
      *
      * @see http://docs.mongodb.org/manual/core/read-preference/
-     * @param ReadPreference $readPreference
      * @return $this
      */
     public function setReadPreference(ReadPreference $readPreference)
@@ -1593,12 +1604,12 @@ public function setQueryArray(array $query)
      *
      * @see Expr::size()
      * @see http://docs.mongodb.org/manual/reference/operator/size/
-     * @param integer $size
+     * @param int $size
      * @return $this
      */
     public function size($size)
     {
-        $this->expr->size((integer) $size);
+        $this->expr->size((int) $size);
         return $this;
     }
 
@@ -1609,24 +1620,24 @@ public function size($size)
      * results in an output collecton and return a cursor.
      *
      * @see Query::prepareCursor()
-     * @param integer $skip
+     * @param int $skip
      * @return $this
      */
     public function skip($skip)
     {
-        $this->query['skip'] = (integer) $skip;
+        $this->query['skip'] = (int) $skip;
         return $this;
     }
 
     /**
      * Set the snapshot cursor flag.
      *
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function snapshot($bool = true)
     {
-        $this->query['snapshot'] = (boolean) $bool;
+        $this->query['snapshot'] = (bool) $bool;
         return $this;
     }
 
@@ -1637,12 +1648,12 @@ public function snapshot($bool = true)
      * field name (key) and order (value) pairs.
      *
      * @param array|string $fieldName Field name or array of field/order pairs
-     * @param int|string $order       Field order (if one field is specified)
+     * @param int|string   $order     Field order (if one field is specified)
      * @return $this
      */
     public function sort($fieldName, $order = 1)
     {
-        if ( ! isset($this->query['sort'])) {
+        if (! isset($this->query['sort'])) {
             $this->query['sort'] = [];
         }
 
@@ -1652,7 +1663,7 @@ public function sort($fieldName, $order = 1)
             if (is_string($order)) {
                 $order = strtolower($order) === 'asc' ? 1 : -1;
             }
-            $this->query['sort'][$fieldName] = (integer) $order;
+            $this->query['sort'][$fieldName] = (int) $order;
         }
 
         return $this;
@@ -1677,7 +1688,7 @@ public function sortMeta($fieldName, $metaDataKeyword)
          * operator. We'll assume that the user knows what they're doing in that
          * case and will not attempt to override the projection.
          */
-        if ( ! isset($this->query['select'][$fieldName])) {
+        if (! isset($this->query['select'][$fieldName])) {
             $this->selectMeta($fieldName, $metaDataKeyword);
         }
 
@@ -1707,7 +1718,7 @@ public function text($search)
      *
      * @see Expr::type()
      * @see http://docs.mongodb.org/manual/reference/operator/type/
-     * @param integer $type
+     * @param int $type
      * @return $this
      */
     public function type($type)
@@ -1760,12 +1771,12 @@ public function updateMany($documentName = null)
     /**
      * Set the "upsert" option for an update or findAndUpdate query.
      *
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function upsert($bool = true)
     {
-        $this->query['upsert'] = (boolean) $bool;
+        $this->query['upsert'] = (bool) $bool;
         return $this;
     }
 
@@ -1774,7 +1785,7 @@ public function upsert($bool = true)
      *
      * @see Expr::where()
      * @see http://docs.mongodb.org/manual/reference/operator/where/
-     * @param string|\MongoDB\BSON\Javascript $javascript
+     * @param string|Javascript $javascript
      * @return $this
      */
     public function where($javascript)
@@ -1792,8 +1803,8 @@ public function where($javascript)
      */
     private function getDiscriminatorValues($classNames)
     {
-        $discriminatorValues = array();
-        $collections = array();
+        $discriminatorValues = [];
+        $collections = [];
         foreach ($classNames as $className) {
             $class = $this->dm->getClassMetadata($className);
             $discriminatorValues[] = $class->discriminatorValue;
diff --git a/lib/Doctrine/ODM/MongoDB/Query/CriteriaMerger.php b/lib/Doctrine/ODM/MongoDB/Query/CriteriaMerger.php
index a6a6a284f5..d531890f9a 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/CriteriaMerger.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/CriteriaMerger.php
@@ -1,7 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
+use function array_filter;
+use function array_values;
+use function count;
+
 /**
  * Utility class for merging query criteria.
  *
@@ -21,7 +27,7 @@ class CriteriaMerger
     public function merge(...$criterias)
     {
         $nonEmptyCriterias = array_values(array_filter($criterias, function (array $criteria) {
-            return !empty($criteria);
+            return ! empty($criteria);
         }));
 
         switch (count($nonEmptyCriterias)) {
diff --git a/lib/Doctrine/ODM/MongoDB/Query/Expr.php b/lib/Doctrine/ODM/MongoDB/Query/Expr.php
index e07374fad5..c39b2fc3ba 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/Expr.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/Expr.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -7,11 +9,24 @@
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
 use GeoJson\Geometry\Geometry;
 use GeoJson\Geometry\Point;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\Javascript;
+use function array_key_exists;
+use function array_map;
+use function array_merge;
+use function array_values;
+use function explode;
+use function func_get_args;
+use function in_array;
+use function is_array;
+use function is_string;
+use function key;
+use function strpos;
+use function strtolower;
 
 /**
  * Query expression builder for ODM.
  *
- * @since       1.0
  */
 class Expr
 {
@@ -52,9 +67,6 @@ class Expr
      */
     private $class;
 
-    /**
-     * @param DocumentManager $dm
-     */
     public function __construct(DocumentManager $dm)
     {
         $this->dm = $dm;
@@ -105,7 +117,9 @@ public function addNor($expression, ...$expressions)
 
         $this->query['$nor'] = array_merge(
             $this->query['$nor'],
-            array_map(function ($expression) { return $expression instanceof Expr ? $expression->getQuery() : $expression; }, func_get_args())
+            array_map(function ($expression) {
+                return $expression instanceof Expr ? $expression->getQuery() : $expression;
+            }, func_get_args())
         );
 
         return $this;
@@ -128,7 +142,9 @@ public function addOr($expression, ...$expressions)
 
         $this->query['$or'] = array_merge(
             $this->query['$or'],
-            array_map(function ($expression) { return $expression instanceof Expr ? $expression->getQuery() : $expression; }, func_get_args())
+            array_map(function ($expression) {
+                return $expression instanceof Expr ? $expression->getQuery() : $expression;
+            }, func_get_args())
         );
 
         return $this;
@@ -180,7 +196,7 @@ public function all(array $values)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/update/bit/
      * @param string $operator
-     * @param int $value
+     * @param int    $value
      * @return $this
      */
     protected function bit($operator, $value)
@@ -222,7 +238,7 @@ public function bitOr($value)
      *
      * @see Builder::bitsAllClear()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAllClear/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAllClear($value)
@@ -237,7 +253,7 @@ public function bitsAllClear($value)
      *
      * @see Builder::bitsAllSet()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAllSet/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAllSet($value)
@@ -252,7 +268,7 @@ public function bitsAllSet($value)
      *
      * @see Builder::bitsAnyClear()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAnyClear/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAnyClear($value)
@@ -267,7 +283,7 @@ public function bitsAnyClear($value)
      *
      * @see Builder::bitsAnySet()
      * @see https://docs.mongodb.org/manual/reference/operator/query/bitsAnySet/
-     * @param int|array|\MongoDB\BSON\Binary $value
+     * @param int|array|Binary $value
      * @return $this
      */
     public function bitsAnySet($value)
@@ -301,11 +317,10 @@ public function bitXor($value)
      * @return $this
      * @throws \BadMethodCallException if the query does not already have $text criteria
      *
-     * @since 1.3
      */
     public function caseSensitive($caseSensitive)
     {
-        if ( ! isset($this->query['$text'])) {
+        if (! isset($this->query['$text'])) {
             throw new \BadMethodCallException('This method requires a $text operator (call text() first)');
         }
 
@@ -365,11 +380,10 @@ public function currentDate($type = 'date')
      * @return $this
      * @throws \BadMethodCallException if the query does not already have $text criteria
      *
-     * @since 1.3
      */
     public function diacriticSensitive($diacriticSensitive)
     {
-        if ( ! isset($this->query['$text'])) {
+        if (! isset($this->query['$text'])) {
             throw new \BadMethodCallException('This method requires a $text operator (call text() first)');
         }
 
@@ -431,12 +445,12 @@ public function equals($value)
      *
      * @see Builder::exists()
      * @see http://docs.mongodb.org/manual/reference/operator/exists/
-     * @param boolean $bool
+     * @param bool $bool
      * @return $this
      */
     public function exists($bool)
     {
-        return $this->operator('$exists', (boolean) $bool);
+        return $this->operator('$exists', (bool) $bool);
     }
 
     /**
@@ -568,9 +582,9 @@ public function geoWithinCenterSphere($x, $y, $radius)
      *
      * @see Builder::geoWithinPolygon()
      * @see http://docs.mongodb.org/manual/reference/operator/polygon/
-     * @param array $point1 First point of the polygon
-     * @param array $point2 Second point of the polygon
-     * @param array $point3 Third point of the polygon
+     * @param array $point1    First point of the polygon
+     * @param array $point2    Second point of the polygon
+     * @param array $point3    Third point of the polygon
      * @param array ...$points Additional points of the polygon
      * @return $this
      * @throws \InvalidArgumentException if less than three points are given
@@ -662,7 +676,7 @@ public function in(array $values)
      *
      * @see Builder::inc()
      * @see http://docs.mongodb.org/manual/reference/operator/inc/
-     * @param float|integer $value
+     * @param float|int $value
      * @return $this
      */
     public function inc($value)
@@ -733,7 +747,7 @@ public function includesReferenceTo($document)
      */
     public function language($language)
     {
-        if ( ! isset($this->query['$text'])) {
+        if (! isset($this->query['$text'])) {
             throw new \BadMethodCallException('This method requires a $text operator (call text() first)');
         }
 
@@ -803,8 +817,8 @@ public function min($value)
      *
      * @see Builder::mod()
      * @see http://docs.mongodb.org/manual/reference/operator/mod/
-     * @param float|integer $divisor
-     * @param float|integer $remainder
+     * @param float|int $divisor
+     * @param float|int $remainder
      * @return $this
      */
     public function mod($divisor, $remainder = 0)
@@ -819,7 +833,7 @@ public function mod($divisor, $remainder = 0)
      *
      * @see Builder::mul()
      * @see http://docs.mongodb.org/manual/reference/operator/mul/
-     * @param float|integer $value
+     * @param float|int $value
      * @return $this
      */
     public function mul($value)
@@ -839,7 +853,7 @@ public function mul($value)
      * @see Builder::near()
      * @see http://docs.mongodb.org/manual/reference/operator/near/
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return $this
      */
     public function near($x, $y = null)
@@ -865,7 +879,7 @@ public function near($x, $y = null)
      * @see Builder::nearSphere()
      * @see http://docs.mongodb.org/manual/reference/operator/nearSphere/
      * @param float|array|Point $x
-     * @param float $y
+     * @param float             $y
      * @return $this
      */
     public function nearSphere($x, $y = null)
@@ -927,7 +941,7 @@ public function notIn(array $values)
      * the operator is set at the top level of the query.
      *
      * @param string $operator
-     * @param mixed $value
+     * @param mixed  $value
      * @return $this
      */
     public function operator($operator, $value)
@@ -977,7 +991,7 @@ public function popLast()
      * {@link Expr::push()} operation.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/update/position/
-     * @param integer $position
+     * @param int $position
      * @return $this
      */
     public function position($position)
@@ -1143,7 +1157,7 @@ public function rename($name)
      * @see Builder::set()
      * @see http://docs.mongodb.org/manual/reference/operator/set/
      * @param mixed $value
-     * @param boolean $atomic
+     * @param bool  $atomic
      * @return $this
      */
     public function set($value, $atomic = true)
@@ -1173,7 +1187,6 @@ public function set($value, $atomic = true)
     /**
      * Sets ClassMetadata for document being queried.
      *
-     * @param ClassMetadata $class
      */
     public function setClassMetadata(ClassMetadata $class)
     {
@@ -1233,12 +1246,12 @@ public function setQuery(array $query)
      *
      * @see Builder::size()
      * @see http://docs.mongodb.org/manual/reference/operator/size/
-     * @param integer $size
+     * @param int $size
      * @return $this
      */
     public function size($size)
     {
-        return $this->operator('$size', (integer) $size);
+        return $this->operator('$size', (int) $size);
     }
 
     /**
@@ -1249,7 +1262,7 @@ public function size($size)
      * used for specifying $slice for a query projection.
      *
      * @see http://docs.mongodb.org/manual/reference/operator/slice/
-     * @param integer $slice
+     * @param int $slice
      * @return $this
      */
     public function slice($slice)
@@ -1269,7 +1282,7 @@ public function slice($slice)
      *
      * @see http://docs.mongodb.org/manual/reference/operator/sort/
      * @param array|string $fieldName Field name or array of field/order pairs
-     * @param int|string $order       Field order (if one field is specified)
+     * @param int|string   $order     Field order (if one field is specified)
      * @return $this
      */
     public function sort($fieldName, $order = null)
@@ -1301,7 +1314,7 @@ public function text($search)
      * @todo Remove support for string $type argument in 2.0
      * @see Builder::type()
      * @see http://docs.mongodb.org/manual/reference/operator/type/
-     * @param integer $type
+     * @param int $type
      * @return $this
      */
     public function type($type)
@@ -1356,7 +1369,7 @@ public function unsetField()
      *
      * @see Builder::where()
      * @see http://docs.mongodb.org/manual/reference/operator/where/
-     * @param string|\MongoDB\BSON\Javascript $javascript
+     * @param string|Javascript $javascript
      * @return $this
      */
     public function where($javascript)
@@ -1401,7 +1414,6 @@ private function getReferenceMapping()
     /**
      * @param int|string $order
      *
-     * @return int
      */
     private function normalizeSortOrder($order): int
     {
@@ -1419,7 +1431,7 @@ private function normalizeSortOrder($order): int
      */
     private function requiresCurrentField()
     {
-        if ( ! $this->currentField) {
+        if (! $this->currentField) {
             throw new \LogicException('This method requires you set a current field using field().');
         }
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Query/Filter/BsonFilter.php b/lib/Doctrine/ODM/MongoDB/Query/Filter/BsonFilter.php
index 2068acd85f..b8bf5762ba 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/Filter/BsonFilter.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/Filter/BsonFilter.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query\Filter;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use function array_key_exists;
 
 /**
  * The base class that user defined filters should extend.
@@ -22,7 +25,7 @@ abstract class BsonFilter
      * Parameters for the filter.
      * @var array
      */
-    protected $parameters = array();
+    protected $parameters = [];
 
     /**
      * Constructs the BsonFilter object.
@@ -37,8 +40,8 @@ final public function __construct(DocumentManager $dm)
     /**
      * Sets a parameter that can be used by the filter.
      *
-     * @param string $name Name of the parameter.
-     * @param mixed $value Value of the parameter.
+     * @param string $name  Name of the parameter.
+     * @param mixed  $value Value of the parameter.
      *
      * @return BsonFilter The current Bson filter.
      */
@@ -61,7 +64,7 @@ final public function setParameter($name, $value)
      */
     final public function getParameter($name)
     {
-        if ( ! array_key_exists($name, $this->parameters)) {
+        if (! array_key_exists($name, $this->parameters)) {
             throw new \InvalidArgumentException("Filter parameter '" . $name . "' is not set.");
         }
         return $this->parameters[$name];
@@ -72,7 +75,6 @@ final public function getParameter($name)
      *
      * If there is no criteria for the class, an empty array should be returned.
      *
-     * @param ClassMetadata $class
      * @return array
      */
     abstract public function addFilterCriteria(ClassMetadata $class);
diff --git a/lib/Doctrine/ODM/MongoDB/Query/FilterCollection.php b/lib/Doctrine/ODM/MongoDB/Query/FilterCollection.php
index 75f93985d3..d1d03b4f6d 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/FilterCollection.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/FilterCollection.php
@@ -1,10 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
+use Doctrine\ODM\MongoDB\Configuration;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
-use Doctrine\ODM\MongoDB\Query\CriteriaMerger;
+use Doctrine\ODM\MongoDB\Query\Filter\BsonFilter;
+use function array_map;
+use function call_user_func_array;
 
 /**
  * Collection class for all the query filters.
@@ -14,14 +19,14 @@ class FilterCollection
     /**
      * The used Configuration.
      *
-     * @var \Doctrine\ODM\MongoDB\Configuration
+     * @var Configuration
      */
     private $config;
 
     /**
      * The DocumentManager that "owns" this FilterCollection instance.
      *
-     * @var \Doctrine\ODM\MongoDB\DocumentManager
+     * @var DocumentManager
      */
     private $dm;
 
@@ -30,7 +35,7 @@ class FilterCollection
      *
      * @var array
      */
-    private $enabledFilters = array();
+    private $enabledFilters = [];
 
     /**
      * The CriteriaMerger instance.
@@ -39,13 +44,7 @@ class FilterCollection
      */
     private $cm;
 
-    /**
-     * Constructor.
-     *
-     * @param DocumentManager $dm
-     * @param CriteriaMerger  $cm
-     */
-    public function __construct(DocumentManager $dm, CriteriaMerger $cm = null)
+    public function __construct(DocumentManager $dm, ?CriteriaMerger $cm = null)
     {
         $this->dm = $dm;
         $this->cm = $cm ?: new CriteriaMerger();
@@ -70,15 +69,15 @@ public function getEnabledFilters()
      *
      * @throws \InvalidArgumentException If the filter does not exist.
      *
-     * @return \Doctrine\ODM\MongoDB\Query\Filter\BsonFilter The enabled filter.
+     * @return BsonFilter The enabled filter.
      */
     public function enable($name)
     {
-        if ( ! $this->has($name)) {
+        if (! $this->has($name)) {
             throw new \InvalidArgumentException("Filter '" . $name . "' does not exist.");
         }
 
-        if ( ! $this->isEnabled($name)) {
+        if (! $this->isEnabled($name)) {
             $filterClass = $this->config->getFilterClassName($name);
             $filterParameters = $this->config->getFilterParameters($name);
             $filter = new $filterClass($this->dm);
@@ -98,7 +97,7 @@ public function enable($name)
      *
      * @param string $name Name of the filter.
      *
-     * @return \Doctrine\ODM\MongoDB\Query\Filter\BsonFilter The disabled filter.
+     * @return BsonFilter The disabled filter.
      *
      * @throws \InvalidArgumentException If the filter does not exist.
      */
@@ -117,13 +116,13 @@ public function disable($name)
      *
      * @param string $name Name of the filter.
      *
-     * @return \Doctrine\ODM\MongoDB\Query\Filter\BsonFilter The filter.
+     * @return BsonFilter The filter.
      *
      * @throws \InvalidArgumentException If the filter is not enabled.
      */
     public function getFilter($name)
     {
-        if ( ! $this->isEnabled($name)) {
+        if (! $this->isEnabled($name)) {
             throw new \InvalidArgumentException("Filter '" . $name . "' is not enabled.");
         }
         return $this->enabledFilters[$name];
@@ -137,7 +136,7 @@ public function getFilter($name)
      */
     public function has($name)
     {
-        return null !== $this->config->getFilterClassName($name);
+        return $this->config->getFilterClassName($name) !== null;
     }
 
     /**
@@ -154,19 +153,20 @@ public function isEnabled($name)
     /**
      * Gets enabled filter criteria.
      *
-     * @param ClassMetadata $class
      * @return array
      */
     public function getFilterCriteria(ClassMetadata $class)
     {
         if (empty($this->enabledFilters)) {
-            return array();
+            return [];
         }
 
         return call_user_func_array(
-            array($this->cm, 'merge'),
+            [$this->cm, 'merge'],
             array_map(
-                function($filter) use ($class) { return $filter->addFilterCriteria($class); },
+                function ($filter) use ($class) {
+                    return $filter->addFilterCriteria($class);
+                },
                 $this->enabledFilters
             )
         );
diff --git a/lib/Doctrine/ODM/MongoDB/Query/Query.php b/lib/Doctrine/ODM/MongoDB/Query/Query.php
index 42a61a7e63..e1074633af 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/Query.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/Query.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -8,39 +10,48 @@
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
 use Doctrine\ODM\MongoDB\Iterator\PrimingIterator;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\MongoDBException;
 use MongoDB\Collection;
 use MongoDB\Driver\Cursor;
 use MongoDB\Operation\FindOneAndUpdate;
-
+use function array_combine;
+use function array_filter;
+use function array_flip;
+use function array_intersect_key;
+use function array_keys;
+use function array_map;
+use function array_merge;
+use function array_values;
+use function is_array;
+use function is_callable;
 
 /**
  * ODM Query wraps the raw Doctrine MongoDB queries to add additional functionality
  * and to hydrate the raw arrays of data to Doctrine document objects.
  *
- * @since       1.0
  */
 class Query implements \IteratorAggregate
 {
-    const TYPE_FIND            = 1;
-    const TYPE_FIND_AND_UPDATE = 2;
-    const TYPE_FIND_AND_REMOVE = 3;
-    const TYPE_INSERT          = 4;
-    const TYPE_UPDATE          = 5;
-    const TYPE_REMOVE          = 6;
-    const TYPE_GROUP           = 7;
-    const TYPE_MAP_REDUCE      = 8;
-    const TYPE_DISTINCT        = 9;
-    const TYPE_COUNT           = 11;
+    public const TYPE_FIND            = 1;
+    public const TYPE_FIND_AND_UPDATE = 2;
+    public const TYPE_FIND_AND_REMOVE = 3;
+    public const TYPE_INSERT          = 4;
+    public const TYPE_UPDATE          = 5;
+    public const TYPE_REMOVE          = 6;
+    public const TYPE_GROUP           = 7;
+    public const TYPE_MAP_REDUCE      = 8;
+    public const TYPE_DISTINCT        = 9;
+    public const TYPE_COUNT           = 11;
 
     /**
      * @deprecated 1.1 Will be removed for 2.0
      */
-    const TYPE_GEO_LOCATION = 10;
+    public const TYPE_GEO_LOCATION = 10;
 
-    const HINT_REFRESH = 1;
+    public const HINT_REFRESH = 1;
     // 2 was used for HINT_SLAVE_OKAY, which was removed in 2.0
-    const HINT_READ_PREFERENCE = 3;
-    const HINT_READ_ONLY = 5;
+    public const HINT_READ_PREFERENCE = 3;
+    public const HINT_READ_ONLY = 5;
 
     /**
      * The DocumentManager instance.
@@ -59,7 +70,7 @@ class Query implements \IteratorAggregate
     /**
      * Whether to hydrate results as document class instances.
      *
-     * @var boolean
+     * @var bool
      */
     private $hydrate = true;
 
@@ -68,14 +79,14 @@ class Query implements \IteratorAggregate
      *
      * @var array
      */
-    private $primers = array();
+    private $primers = [];
 
     /**
      * Hints for UnitOfWork behavior.
      *
      * @var array
      */
-    private $unitOfWorkHints = array();
+    private $unitOfWorkHints = [];
 
     /**
      * The Collection instance.
@@ -104,29 +115,26 @@ class Query implements \IteratorAggregate
     private $options;
 
     /**
-     * Constructor.
+     *
      *
      * Please note that $requireIndexes was deprecated in 1.2 and will be removed in 2.0
      *
-     * @param DocumentManager $dm
-     * @param ClassMetadata $class
-     * @param Collection $collection
      * @param array $query
      * @param array $options
-     * @param boolean $hydrate
-     * @param boolean $refresh
+     * @param bool  $hydrate
+     * @param bool  $refresh
      * @param array $primers
-     * @param boolean $readOnly
+     * @param bool  $readOnly
      */
-    public function __construct(DocumentManager $dm, ClassMetadata $class, Collection $collection, array $query = array(), array $options = array(), $hydrate = true, $refresh = false, array $primers = array(), $readOnly = false)
+    public function __construct(DocumentManager $dm, ClassMetadata $class, Collection $collection, array $query = [], array $options = [], $hydrate = true, $refresh = false, array $primers = [], $readOnly = false)
     {
         $primers = array_filter($primers);
 
-        if ( ! empty($primers)) {
+        if (! empty($primers)) {
             $query['eagerCursor'] = true;
         }
 
-        if ( ! empty($query['eagerCursor'])) {
+        if (! empty($query['eagerCursor'])) {
             $query['useIdentifierKeys'] = false;
         }
 
@@ -186,14 +194,14 @@ public function debug($name = null)
     /**
      * Execute the query and returns the results.
      *
-     * @throws \Doctrine\ODM\MongoDB\MongoDBException
+     * @throws MongoDBException
      * @return Iterator|int|string|array
      */
     public function execute()
     {
         $results = $this->runQuery();
 
-        if ( ! $this->hydrate) {
+        if (! $this->hydrate) {
             return $results;
         }
 
@@ -209,15 +217,14 @@ public function execute()
         if (($this->query['type'] === self::TYPE_FIND_AND_UPDATE ||
                 $this->query['type'] === self::TYPE_FIND_AND_REMOVE) &&
             is_array($results) && isset($results['_id'])) {
-
             $results = $uow->getOrCreateDocument($this->class->name, $results, $this->unitOfWorkHints);
 
-            if ( ! empty($this->primers)) {
+            if (! empty($this->primers)) {
                 $referencePrimer = new ReferencePrimer($this->dm, $uow);
 
                 foreach ($this->primers as $fieldName => $primer) {
                     $primer = is_callable($primer) ? $primer : null;
-                    $referencePrimer->primeReferences($this->class, array($results), $fieldName, $this->unitOfWorkHints, $primer);
+                    $referencePrimer->primeReferences($this->class, [$results], $fieldName, $this->unitOfWorkHints, $primer);
                 }
             }
         }
@@ -303,7 +310,7 @@ public function getSingleResult()
     /**
      * Return the query type.
      *
-     * @return integer
+     * @return int
      */
     public function getType()
     {
@@ -313,11 +320,11 @@ public function getType()
     /**
      * Sets whether or not to hydrate the documents to objects.
      *
-     * @param boolean $hydrate
+     * @param bool $hydrate
      */
     public function setHydrate($hydrate)
     {
-        $this->hydrate = (boolean) $hydrate;
+        $this->hydrate = (bool) $hydrate;
     }
 
     /**
@@ -326,11 +333,11 @@ public function setHydrate($hydrate)
      *
      * This option has no effect if hydration is disabled.
      *
-     * @param boolean $readOnly
+     * @param bool $readOnly
      */
     public function setReadOnly($readOnly)
     {
-        $this->unitOfWorkHints[Query::HINT_READ_ONLY] = (boolean) $readOnly;
+        $this->unitOfWorkHints[self::HINT_READ_ONLY] = (bool) $readOnly;
     }
 
     /**
@@ -339,11 +346,11 @@ public function setReadOnly($readOnly)
      *
      * This option has no effect if hydration is disabled.
      *
-     * @param boolean $refresh
+     * @param bool $refresh
      */
     public function setRefresh($refresh)
     {
-        $this->unitOfWorkHints[Query::HINT_REFRESH] = (boolean) $refresh;
+        $this->unitOfWorkHints[self::HINT_REFRESH] = (bool) $refresh;
     }
 
     /**
@@ -368,7 +375,9 @@ private function getQueryOptions(string ...$keys)
     {
         return array_filter(
             array_intersect_key($this->query, array_flip($keys)),
-            function($value) { return $value !== null; }
+            function ($value) {
+                return $value !== null;
+            }
         );
     }
 
@@ -380,7 +389,7 @@ private function makeIterator(Cursor $cursor): Iterator
 
         $cursor = new CachingIterator($cursor);
 
-        if ( ! empty($this->primers)) {
+        if (! empty($this->primers)) {
             $referencePrimer = new ReferencePrimer($this->dm, $this->dm->getUnitOfWork());
             $cursor = new PrimingIterator($cursor, $this->class, $referencePrimer, $this->primers, $this->unitOfWorkHints);
         }
@@ -402,7 +411,9 @@ private function renameQueryOptions(array $options, array $rename)
 
         return array_combine(
             array_map(
-                function($key) use ($rename) { return $rename[$key] ?? $key; },
+                function ($key) use ($rename) {
+                    return $rename[$key] ?? $key;
+                },
                 array_keys($options)
             ),
             array_values($options)
diff --git a/lib/Doctrine/ODM/MongoDB/Query/QueryExpressionVisitor.php b/lib/Doctrine/ODM/MongoDB/Query/QueryExpressionVisitor.php
index 2ec17e8c3e..8cdc2fdfcb 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/QueryExpressionVisitor.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/QueryExpressionVisitor.php
@@ -1,16 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
 use Doctrine\Common\Collections\Expr\Comparison;
 use Doctrine\Common\Collections\Expr\CompositeExpression;
 use Doctrine\Common\Collections\Expr\ExpressionVisitor;
 use Doctrine\Common\Collections\Expr\Value;
+use MongoDB\BSON\Regex;
 
 /**
  * Converts Collection expressions to query expressions.
  *
- * @since  1.0
  */
 class QueryExpressionVisitor extends ExpressionVisitor
 {
@@ -20,7 +22,7 @@ class QueryExpressionVisitor extends ExpressionVisitor
      * @todo Implement support for Comparison::CONTAINS
      * @var array
      */
-    private static $operatorMethods = array(
+    private static $operatorMethods = [
         Comparison::EQ => 'equals',
         Comparison::GT => 'gt',
         Comparison::GTE => 'gte',
@@ -30,28 +32,23 @@ class QueryExpressionVisitor extends ExpressionVisitor
         Comparison::LTE => 'lte',
         Comparison::NEQ => 'notEqual',
         Comparison::NIN => 'notIn',
-    );
+    ];
 
     /**
      * Map Criteria API composite types to query builder methods
      *
      * @var array
      */
-    private static $compositeMethods = array(
+    private static $compositeMethods = [
         CompositeExpression::TYPE_AND => 'addAnd',
         CompositeExpression::TYPE_OR => 'addOr',
-    );
+    ];
 
     /**
      * @var Builder
      */
     protected $builder;
 
-    /**
-     * Constructor.
-     *
-     * @param Builder $builder
-     */
     public function __construct(Builder $builder)
     {
         $this->builder = $builder;
@@ -61,8 +58,7 @@ public function __construct(Builder $builder)
      * Converts a comparison expression into the target query language output.
      *
      * @see ExpressionVisitor::walkComparison()
-     * @param Comparison $comparison
-     * @return \Doctrine\ODM\MongoDB\Query\Expr
+     * @return Expr
      */
     public function walkComparison(Comparison $comparison)
     {
@@ -87,7 +83,7 @@ public function walkComparison(Comparison $comparison)
 
                 return $this->builder->expr()
                     ->field($comparison->getField())
-                    ->equals(new \MongoDB\BSON\Regex($value, ''));
+                    ->equals(new Regex($value, ''));
 
             default:
                 throw new \RuntimeException('Unknown comparison operator: ' . $comparison->getOperator());
@@ -98,12 +94,11 @@ public function walkComparison(Comparison $comparison)
      * Converts a composite expression into the target query language output.
      *
      * @see ExpressionVisitor::walkCompositeExpression()
-     * @param CompositeExpression $compositeExpr
-     * @return \Doctrine\ODM\MongoDB\Query\Expr
+     * @return Expr
      */
     public function walkCompositeExpression(CompositeExpression $compositeExpr)
     {
-        if ( ! isset(self::$compositeMethods[$compositeExpr->getType()])) {
+        if (! isset(self::$compositeMethods[$compositeExpr->getType()])) {
             throw new \RuntimeException('Unknown composite ' . $compositeExpr->getType());
         }
 
@@ -121,7 +116,6 @@ public function walkCompositeExpression(CompositeExpression $compositeExpr)
      * Converts a value expression into the target query language part.
      *
      * @see ExpressionVisitor::walkValue()
-     * @param Value $value
      * @return mixed
      */
     public function walkValue(Value $value)
diff --git a/lib/Doctrine/ODM/MongoDB/Query/ReferencePrimer.php b/lib/Doctrine/ODM/MongoDB/Query/ReferencePrimer.php
index 29c3cb6c5b..bcbca29d4b 100644
--- a/lib/Doctrine/ODM/MongoDB/Query/ReferencePrimer.php
+++ b/lib/Doctrine/ODM/MongoDB/Query/ReferencePrimer.php
@@ -1,14 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Query;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
-use Doctrine\ODM\MongoDB\PersistentCollection;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\UnitOfWork;
-use MongoDB\Driver\ReadPreference;
+use function array_push;
+use function array_shift;
+use function array_values;
+use function call_user_func;
+use function count;
+use function explode;
+use function get_class;
+use function implode;
+use function is_callable;
+use function is_object;
+use function serialize;
+use function sprintf;
 
 /**
  * The ReferencePrimer is responsible for priming reference relationships.
@@ -20,7 +32,6 @@
  * Priming can only be used for the owning side side of a relationship, since
  * the referenced identifiers are not immediately available on an inverse side.
  *
- * @since  1.0
  */
 class ReferencePrimer
 {
@@ -48,19 +59,19 @@ class ReferencePrimer
     /**
      * Initializes this instance with the specified document manager and unit of work.
      *
-     * @param DocumentManager $dm Document manager.
-     * @param UnitOfWork $uow Unit of work.
+     * @param DocumentManager $dm  Document manager.
+     * @param UnitOfWork      $uow Unit of work.
      */
     public function __construct(DocumentManager $dm, UnitOfWork $uow)
     {
         $this->dm = $dm;
         $this->uow = $uow;
 
-        $this->defaultPrimer = function(DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) {
+        $this->defaultPrimer = function (DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) {
             $qb = $dm->createQueryBuilder($class->name)
                 ->field($class->identifier)->in($ids);
 
-            if ( ! empty($hints[Query::HINT_READ_PREFERENCE])) {
+            if (! empty($hints[Query::HINT_READ_PREFERENCE])) {
                 $qb->setReadPreference($hints[Query::HINT_READ_PREFERENCE]);
             }
 
@@ -87,7 +98,7 @@ public function __construct(DocumentManager $dm, UnitOfWork $uow)
      * @throws \LogicException If the mapped field is a simple reference and is
      *                         missing a target document class.
      */
-    public function primeReferences(ClassMetadata $class, $documents, $fieldName, array $hints = array(), $primer = null)
+    public function primeReferences(ClassMetadata $class, $documents, $fieldName, array $hints = [], $primer = null)
     {
         $data = $this->parseDotSyntaxForPrimer($fieldName, $class, $documents);
         $mapping = $data['mapping'];
@@ -98,7 +109,7 @@ public function primeReferences(ClassMetadata $class, $documents, $fieldName, ar
         /* Inverse-side references would need to be populated before we can
          * collect references to be primed. This is not supported.
          */
-        if ( ! isset($mapping['reference']) || ! $mapping['isOwningSide']) {
+        if (! isset($mapping['reference']) || ! $mapping['isOwningSide']) {
             throw new \InvalidArgumentException(sprintf('Field "%s" is not the owning side of a reference relationship in class "%s"', $fieldName, $class->name));
         }
 
@@ -114,7 +125,7 @@ public function primeReferences(ClassMetadata $class, $documents, $fieldName, ar
         }
 
         $primer = $primer ?: $this->defaultPrimer;
-        $groupedIds = array();
+        $groupedIds = [];
 
         /* @var $document PersistentCollectionInterface */
         foreach ($documents as $document) {
@@ -123,7 +134,7 @@ public function primeReferences(ClassMetadata $class, $documents, $fieldName, ar
             /* The field will need to be either a Proxy (reference-one) or
              * PersistentCollection (reference-many) in order to prime anything.
              */
-            if ( ! is_object($fieldValue)) {
+            if (! is_object($fieldValue)) {
                 continue;
             }
 
@@ -131,7 +142,7 @@ public function primeReferences(ClassMetadata $class, $documents, $fieldName, ar
                 $refClass = $this->dm->getClassMetadata(get_class($fieldValue));
                 $id = $this->uow->getDocumentIdentifier($fieldValue);
                 $groupedIds[$refClass->name][serialize($id)] = $id;
-            } elseif ($mapping['type'] == 'many' && $fieldValue instanceof PersistentCollectionInterface) {
+            } elseif ($mapping['type'] === 'many' && $fieldValue instanceof PersistentCollectionInterface) {
                 $this->addManyReferences($fieldValue, $groupedIds);
             }
         }
@@ -159,14 +170,14 @@ public function primeReferences(ClassMetadata $class, $documents, $fieldName, ar
     private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mapping = null)
     {
         // Recursion passthrough:
-        if ($mapping != null) {
-            return array('fieldName' => $fieldName, 'class' => $class, 'documents' => $documents, 'mapping' => $mapping);
+        if ($mapping !== null) {
+            return ['fieldName' => $fieldName, 'class' => $class, 'documents' => $documents, 'mapping' => $mapping];
         }
 
         // Gather mapping data:
         $e = explode('.', $fieldName);
 
-        if ( ! isset($class->fieldMappings[$e[0]])) {
+        if (! isset($class->fieldMappings[$e[0]])) {
             throw new \InvalidArgumentException(sprintf('Field %s cannot be further parsed for priming because it is unmapped.', $fieldName));
         }
 
@@ -174,16 +185,16 @@ private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mappin
         $e[0] = $mapping['fieldName'];
 
         // Case of embedded document(s) to recurse through:
-        if ( ! isset($mapping['reference'])) {
+        if (! isset($mapping['reference'])) {
             if (empty($mapping['embedded'])) {
                 throw new \InvalidArgumentException(sprintf('Field "%s" of fieldName "%s" is not an embedded document, therefore no children can be primed. Aborting. This feature does not support traversing nested referenced documents at this time.', $e[0], $fieldName));
             }
 
-            if ( ! isset($mapping['targetDocument'])) {
+            if (! isset($mapping['targetDocument'])) {
                 throw new \InvalidArgumentException(sprintf('No target document class has been specified for this embedded document. However, targetDocument mapping must be specified in order for prime to work on fieldName "%s" for mapping of field "%s".', $fieldName, $mapping['fieldName']));
             }
 
-            $childDocuments = array();
+            $childDocuments = [];
 
             foreach ($documents as $document) {
                 $fieldValue = $class->getFieldValue($document, $e[0]);
@@ -193,7 +204,7 @@ private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mappin
                         array_push($childDocuments, $elemDocument);
                     }
                 } else {
-                    array_push($childDocuments,$fieldValue);
+                    array_push($childDocuments, $fieldValue);
                 }
             }
 
@@ -201,11 +212,11 @@ private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mappin
 
             $childClass = $this->dm->getClassMetadata($mapping['targetDocument']);
 
-            if ( ! $childClass->hasField($e[0])) {
+            if (! $childClass->hasField($e[0])) {
                 throw new \InvalidArgumentException(sprintf('Field to prime must exist in embedded target document. Reference fieldName "%s" for mapping of target document class "%s".', $fieldName, $mapping['targetDocument']));
             }
 
-            $childFieldName = implode('.',$e);
+            $childFieldName = implode('.', $e);
 
             return $this->parseDotSyntaxForPrimer($childFieldName, $childClass, $childDocuments);
         }
@@ -216,7 +227,7 @@ private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mappin
                 throw new \InvalidArgumentException(sprintf('Cannot prime more than one layer deep but field "%s" is a reference and has children in fieldName "%s".', $e[0], $fieldName));
             }
 
-            return array('fieldName' => $fieldName, 'class' => $class, 'documents' => $documents, 'mapping' => $mapping);
+            return ['fieldName' => $fieldName, 'class' => $class, 'documents' => $documents, 'mapping' => $mapping];
         }
     }
 
@@ -227,8 +238,7 @@ private function parseDotSyntaxForPrimer($fieldName, $class, $documents, $mappin
      * have a target document class defined. Without that, there is no way to
      * infer the class of the referenced documents.
      *
-     * @param PersistentCollectionInterface $persistentCollection
-     * @param array                $groupedIds
+     * @param array $groupedIds
      */
     private function addManyReferences(PersistentCollectionInterface $persistentCollection, array &$groupedIds)
     {
@@ -251,7 +261,7 @@ private function addManyReferences(PersistentCollectionInterface $persistentColl
 
             $document = $this->uow->tryGetById($id, $class);
 
-            if ( ! $document || ($document instanceof Proxy && ! $document->__isInitialized())) {
+            if (! $document || ($document instanceof Proxy && ! $document->__isInitialized())) {
                 $id = $class->getPHPIdentifierValue($id);
                 $groupedIds[$className][serialize($id)] = $id;
             }
diff --git a/lib/Doctrine/ODM/MongoDB/Repository/AbstractRepositoryFactory.php b/lib/Doctrine/ODM/MongoDB/Repository/AbstractRepositoryFactory.php
index 9c3f555fcf..6b05f65508 100644
--- a/lib/Doctrine/ODM/MongoDB/Repository/AbstractRepositoryFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Repository/AbstractRepositoryFactory.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Repository;
 
 use Doctrine\Common\Persistence\ObjectRepository;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use function ltrim;
+use function spl_object_hash;
 
 /**
  * Abstract factory for creating document repositories.
  *
- * @since 1.2
  */
 abstract class AbstractRepositoryFactory implements RepositoryFactory
 {
@@ -18,7 +21,7 @@ abstract class AbstractRepositoryFactory implements RepositoryFactory
      *
      * @var ObjectRepository[]
      */
-    private $repositoryList = array();
+    private $repositoryList = [];
 
     /**
      * {@inheritdoc}
@@ -59,8 +62,6 @@ protected function createRepository(DocumentManager $documentManager, $documentN
      * Instantiates requested repository.
      *
      * @param string $repositoryClassName
-     * @param DocumentManager $documentManager
-     * @param ClassMetadata $metadata
      * @return ObjectRepository
      */
     abstract protected function instantiateRepository($repositoryClassName, DocumentManager $documentManager, ClassMetadata $metadata);
diff --git a/lib/Doctrine/ODM/MongoDB/Repository/DefaultRepositoryFactory.php b/lib/Doctrine/ODM/MongoDB/Repository/DefaultRepositoryFactory.php
index cd934eac82..e5e79bcc18 100644
--- a/lib/Doctrine/ODM/MongoDB/Repository/DefaultRepositoryFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Repository/DefaultRepositoryFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Repository;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
diff --git a/lib/Doctrine/ODM/MongoDB/Repository/RepositoryFactory.php b/lib/Doctrine/ODM/MongoDB/Repository/RepositoryFactory.php
index 5314f81dd6..da7c653499 100644
--- a/lib/Doctrine/ODM/MongoDB/Repository/RepositoryFactory.php
+++ b/lib/Doctrine/ODM/MongoDB/Repository/RepositoryFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Repository;
 
 use Doctrine\Common\Persistence\ObjectRepository;
diff --git a/lib/Doctrine/ODM/MongoDB/SchemaManager.php b/lib/Doctrine/ODM/MongoDB/SchemaManager.php
index 7aed337961..5290d81263 100644
--- a/lib/Doctrine/ODM/MongoDB/SchemaManager.php
+++ b/lib/Doctrine/ODM/MongoDB/SchemaManager.php
@@ -1,12 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use MongoDB\Driver\Exception\RuntimeException;
-use MongoDB\Driver\WriteConcern;
 use MongoDB\Model\IndexInfo;
+use function array_filter;
+use function array_unique;
+use function iterator_to_array;
+use function strpos;
 
 class SchemaManager
 {
@@ -21,10 +26,6 @@ class SchemaManager
      */
     protected $metadataFactory;
 
-    /**
-     * @param DocumentManager $dm
-     * @param ClassMetadataFactory $cmf
-     */
     public function __construct(DocumentManager $dm, ClassMetadataFactory $cmf)
     {
         $this->dm = $dm;
@@ -35,7 +36,7 @@ public function __construct(DocumentManager $dm, ClassMetadataFactory $cmf)
      * Ensure indexes are created for all documents that can be loaded with the
      * metadata factory.
      *
-     * @param integer $timeout Timeout (ms) for acknowledged index creation
+     * @param int $timeout Timeout (ms) for acknowledged index creation
      */
     public function ensureIndexes($timeout = null)
     {
@@ -53,7 +54,7 @@ public function ensureIndexes($timeout = null)
      * Indexes that exist in MongoDB but not the document metadata will be
      * deleted.
      *
-     * @param integer $timeout Timeout (ms) for acknowledged index creation
+     * @param int $timeout Timeout (ms) for acknowledged index creation
      */
     public function updateIndexes($timeout = null)
     {
@@ -72,7 +73,7 @@ public function updateIndexes($timeout = null)
      * deleted.
      *
      * @param string $documentName
-     * @param integer $timeout Timeout (ms) for acknowledged index creation
+     * @param int    $timeout      Timeout (ms) for acknowledged index creation
      * @throws \InvalidArgumentException
      */
     public function updateDocumentIndexes($documentName, $timeout = null)
@@ -92,7 +93,7 @@ public function updateDocumentIndexes($documentName, $timeout = null)
          */
         $self = $this;
         $mongoIndexes = array_filter($mongoIndexes, function (IndexInfo $mongoIndex) use ($documentIndexes, $self) {
-            if ('_id_' === $mongoIndex['name']) {
+            if ($mongoIndex['name'] === '_id_') {
                 return false;
             }
 
@@ -123,32 +124,32 @@ public function updateDocumentIndexes($documentName, $timeout = null)
      */
     public function getDocumentIndexes($documentName)
     {
-        $visited = array();
+        $visited = [];
         return $this->doGetDocumentIndexes($documentName, $visited);
     }
 
     /**
      * @param string $documentName
-     * @param array $visited
+     * @param array  $visited
      * @return array
      */
     private function doGetDocumentIndexes($documentName, array &$visited)
     {
         if (isset($visited[$documentName])) {
-            return array();
+            return [];
         }
 
         $visited[$documentName] = true;
 
         $class = $this->dm->getClassMetadata($documentName);
         $indexes = $this->prepareIndexes($class);
-        $embeddedDocumentIndexes = array();
+        $embeddedDocumentIndexes = [];
 
         // Add indexes from embedded & referenced documents
         foreach ($class->fieldMappings as $fieldMapping) {
             if (isset($fieldMapping['embedded'])) {
                 if (isset($fieldMapping['targetDocument'])) {
-                    $possibleEmbeds = array($fieldMapping['targetDocument']);
+                    $possibleEmbeds = [$fieldMapping['targetDocument']];
                 } elseif (isset($fieldMapping['discriminatorMap'])) {
                     $possibleEmbeds = array_unique($fieldMapping['discriminatorMap']);
                 } else {
@@ -171,9 +172,9 @@ private function doGetDocumentIndexes($documentName, array &$visited)
                 }
             } elseif (isset($fieldMapping['reference']) && isset($fieldMapping['targetDocument'])) {
                 foreach ($indexes as $idx => $index) {
-                    $newKeys = array();
+                    $newKeys = [];
                     foreach ($index['keys'] as $key => $v) {
-                        if ($key == $fieldMapping['name']) {
+                        if ($key === $fieldMapping['name']) {
                             $key = ClassMetadata::getReferenceFieldName($fieldMapping['storeAs'], $key);
                         }
                         $newKeys[$key] = $v;
@@ -186,20 +187,19 @@ private function doGetDocumentIndexes($documentName, array &$visited)
     }
 
     /**
-     * @param ClassMetadata $class
      * @return array
      */
     private function prepareIndexes(ClassMetadata $class)
     {
         $persister = $this->dm->getUnitOfWork()->getDocumentPersister($class->name);
         $indexes = $class->getIndexes();
-        $newIndexes = array();
+        $newIndexes = [];
 
         foreach ($indexes as $index) {
-            $newIndex = array(
-                'keys' => array(),
-                'options' => $index['options']
-            );
+            $newIndex = [
+                'keys' => [],
+                'options' => $index['options'],
+            ];
             foreach ($index['keys'] as $key => $value) {
                 $key = $persister->prepareFieldName($key);
                 if ($class->hasField($key)) {
@@ -220,7 +220,7 @@ private function prepareIndexes(ClassMetadata $class)
      * Ensure the given document's indexes are created.
      *
      * @param string $documentName
-     * @param integer $timeout Timeout (ms) for acknowledged index creation
+     * @param int    $timeout      Timeout (ms) for acknowledged index creation
      * @throws \InvalidArgumentException
      */
     public function ensureDocumentIndexes($documentName, $timeout = null)
@@ -235,7 +235,7 @@ public function ensureDocumentIndexes($documentName, $timeout = null)
                 $keys = $index['keys'];
                 $options = $index['options'];
 
-                if ( ! isset($options['timeout']) && isset($timeout)) {
+                if (! isset($options['timeout']) && isset($timeout)) {
                     $options['timeout'] = $timeout;
                 }
 
@@ -384,15 +384,15 @@ public function dropDocumentDatabase($documentName)
      * the unique index. Additionally, the background option is only
      * relevant to index creation and is not considered.
      *
-     * @param array|IndexInfo $mongoIndex Mongo index data.
-     * @param array $documentIndex Document index data.
+     * @param array|IndexInfo $mongoIndex    Mongo index data.
+     * @param array           $documentIndex Document index data.
      * @return bool True if the indexes are equivalent, otherwise false.
      */
     public function isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentIndex)
     {
         $documentIndexOptions = $documentIndex['options'];
 
-        if ($mongoIndex['key'] != $documentIndex['keys']) {
+        if ($mongoIndex['key'] !== $documentIndex['keys']) {
             return false;
         }
 
@@ -404,20 +404,18 @@ public function isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentInde
             return false;
         }
 
-        if ( ! empty($mongoIndex['unique']) && empty($mongoIndex['dropDups']) &&
+        if (! empty($mongoIndex['unique']) && empty($mongoIndex['dropDups']) &&
             ! empty($documentIndexOptions['unique']) && ! empty($documentIndexOptions['dropDups'])) {
-
             return false;
         }
 
-        foreach (array('bits', 'max', 'min') as $option) {
+        foreach (['bits', 'max', 'min'] as $option) {
             if (isset($mongoIndex[$option]) xor isset($documentIndexOptions[$option])) {
                 return false;
             }
 
             if (isset($mongoIndex[$option]) && isset($documentIndexOptions[$option]) &&
                 $mongoIndex[$option] !== $documentIndexOptions[$option]) {
-
                 return false;
             }
         }
@@ -428,7 +426,6 @@ public function isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentInde
 
         if (isset($mongoIndex['partialFilterExpression']) && isset($documentIndexOptions['partialFilterExpression']) &&
             $mongoIndex['partialFilterExpression'] !== $documentIndexOptions['partialFilterExpression']) {
-
             return false;
         }
 
@@ -443,10 +440,10 @@ public function isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentInde
      *
      * @throws MongoDBException
      */
-    public function ensureSharding(array $indexOptions = array())
+    public function ensureSharding(array $indexOptions = [])
     {
         foreach ($this->metadataFactory->getAllMetadata() as $class) {
-            if ($class->isMappedSuperclass || !$class->isSharded()) {
+            if ($class->isMappedSuperclass || ! $class->isSharded()) {
                 continue;
             }
 
@@ -462,10 +459,10 @@ public function ensureSharding(array $indexOptions = array())
      *
      * @throws MongoDBException
      */
-    public function ensureDocumentSharding($documentName, array $indexOptions = array())
+    public function ensureDocumentSharding($documentName, array $indexOptions = [])
     {
         $class = $this->dm->getClassMetadata($documentName);
-        if ( ! $class->isSharded()) {
+        if (! $class->isSharded()) {
             return;
         }
 
@@ -478,7 +475,7 @@ public function ensureDocumentSharding($documentName, array $indexOptions = arra
                 $done = true;
 
                 // Need to check error message because MongoDB 3.0 does not return a code for this error
-                if ($result['ok'] != 1 && strpos($result['errmsg'], 'please create an index that starts') !== false) {
+                if (! (bool) $result['ok'] && strpos($result['errmsg'], 'please create an index that starts') !== false) {
                     // The proposed key is not returned when using mongo-php-adapter with ext-mongodb.
                     // See https://github.com/mongodb/mongo-php-driver/issues/296 for details
                     $key = $result['proposedKey'] ?? $this->dm->getClassMetadata($documentName)->getShardKey()['keys'];
@@ -487,7 +484,7 @@ public function ensureDocumentSharding($documentName, array $indexOptions = arra
                     $done = false;
                 }
             } catch (RuntimeException $e) {
-                if ($e->getCode() === 20 || $e->getMessage() == 'already sharded') {
+                if ($e->getCode() === 20 || $e->getCode() === 23 || $e->getMessage() === 'already sharded') {
                     return;
                 }
 
@@ -497,7 +494,7 @@ public function ensureDocumentSharding($documentName, array $indexOptions = arra
 
         // Starting with MongoDB 3.2, this command returns code 20 when a collection is already sharded.
         // For older MongoDB versions, check the error message
-        if ($result['ok'] == 1 || (isset($result['code']) && $result['code'] == 20) || $result['errmsg'] == 'already sharded') {
+        if ((bool) $result['ok'] || (isset($result['code']) && $result['code'] === 20) || $result['errmsg'] === 'already sharded') {
             return;
         }
 
@@ -517,7 +514,7 @@ public function enableShardingForDbByDocumentName($documentName)
         $adminDb = $this->dm->getClient()->selectDatabase('admin');
 
         try {
-            $adminDb->command(array('enableSharding' => $dbName));
+            $adminDb->command(['enableSharding' => $dbName]);
         } catch (RuntimeException $e) {
             if ($e->getCode() !== 23 || $e->getMessage() === 'already enabled') {
                 throw MongoDBException::failedToEnableSharding($dbName, $e->getMessage());
@@ -538,10 +535,10 @@ private function runShardCollectionCommand($documentName)
         $adminDb = $this->dm->getClient()->selectDatabase('admin');
 
         $result = $adminDb->command(
-            array(
+            [
                 'shardCollection' => $dbName . '.' . $class->getCollection(),
-                'key'             => $shardKey['keys']
-            )
+                'key'             => $shardKey['keys'],
+            ]
         )->toArray()[0];
 
         return $result;
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/ClearCache/MetadataCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/ClearCache/MetadataCommand.php
index c7b3cab89f..e7c4bca4a5 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/ClearCache/MetadataCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/ClearCache/MetadataCommand.php
@@ -1,17 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\ClearCache;
 
 use Doctrine\Common\Cache\ApcCache;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
+use const PHP_EOL;
 
 /**
  * Command to clear the metadata cache of the various cache drivers.
  *
- * @since   1.0
- * @version $Revision$
  */
 class MetadataCommand extends Command
 {
@@ -23,7 +24,7 @@ protected function configure()
         $this
         ->setName('odm:clear-cache:metadata')
         ->setDescription('Clear all metadata cache of the various cache drivers.')
-        ->setDefinition(array())
+        ->setDefinition([])
         ->setHelp(<<<EOT
 Clear all metadata cache of the various cache drivers.
 EOT
@@ -38,12 +39,12 @@ protected function execute(InputInterface $input, OutputInterface $output)
         $dm = $this->getHelper('documentManager')->getDocumentManager();
         $cacheDriver = $dm->getConfiguration()->getMetadataCacheImpl();
 
-        if ( ! $cacheDriver) {
+        if (! $cacheDriver) {
             throw new \InvalidArgumentException('No Metadata cache driver is configured on given DocumentManager.');
         }
 
         if ($cacheDriver instanceof ApcCache) {
-            throw new \LogicException("Cannot clear APC Cache from Console, its shared in the Webserver memory and not accessible from the CLI.");
+            throw new \LogicException('Cannot clear APC Cache from Console, its shared in the Webserver memory and not accessible from the CLI.');
         }
 
         $output->write('Clearing ALL Metadata cache entries' . PHP_EOL);
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateHydratorsCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateHydratorsCommand.php
index d2c3d4feaa..cb52181060 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateHydratorsCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateHydratorsCommand.php
@@ -1,16 +1,25 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command;
 
+use Doctrine\ODM\MongoDB\Tools\Console\MetadataFilter;
+use Symfony\Component\Console;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputOption;
-use Symfony\Component\Console;
-use Doctrine\ODM\MongoDB\Tools\Console\MetadataFilter;
+use const PHP_EOL;
+use function count;
+use function file_exists;
+use function is_dir;
+use function is_writable;
+use function mkdir;
+use function realpath;
+use function sprintf;
 
 /**
  * Command to (re)generate the hydrator classes used by doctrine.
  *
- * @since   1.0
  */
 class GenerateHydratorsCommand extends Console\Command\Command
 {
@@ -22,16 +31,19 @@ protected function configure()
         $this
         ->setName('odm:generate:hydrators')
         ->setDescription('Generates hydrator classes for document classes.')
-        ->setDefinition(array(
+        ->setDefinition([
             new InputOption(
-                'filter', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
+                'filter',
+                null,
+                InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
                 'A string pattern used to match documents that should be processed.'
             ),
             new InputArgument(
-                'dest-path', InputArgument::OPTIONAL,
+                'dest-path',
+                InputArgument::OPTIONAL,
                 'The path to generate your hydrator classes. If none is provided, it will attempt to grab from configuration.'
             ),
-        ))
+        ])
         ->setHelp(<<<EOT
 Generates hydrator classes for document classes.
 EOT
@@ -44,7 +56,7 @@ protected function configure()
     protected function execute(Console\Input\InputInterface $input, Console\Output\OutputInterface $output)
     {
         $dm = $this->getHelper('documentManager')->getDocumentManager();
-        
+
         $metadatas = $dm->getMetadataFactory()->getAllMetadata();
         $metadatas = MetadataFilter::filter($metadatas, $input->getOption('filter'));
 
@@ -53,17 +65,17 @@ protected function execute(Console\Input\InputInterface $input, Console\Output\O
             $destPath = $dm->getConfiguration()->getHydratorDir();
         }
 
-        if ( ! is_dir($destPath)) {
+        if (! is_dir($destPath)) {
             mkdir($destPath, 0775, true);
         }
 
         $destPath = realpath($destPath);
 
-        if ( ! file_exists($destPath)) {
+        if (! file_exists($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Hydrators destination directory '<info>%s</info>' does not exist.", $destPath)
             );
-        } elseif ( ! is_writable($destPath)) {
+        } elseif (! is_writable($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Hydrators destination directory '<info>%s</info>' does not have write permissions.", $destPath)
             );
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GeneratePersistentCollectionsCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GeneratePersistentCollectionsCommand.php
index ead7e9054d..48b90f7776 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GeneratePersistentCollectionsCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GeneratePersistentCollectionsCommand.php
@@ -1,16 +1,25 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command;
 
 use Doctrine\ODM\MongoDB\Tools\Console\MetadataFilter;
+use Symfony\Component\Console;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputOption;
-use Symfony\Component\Console;
+use const PHP_EOL;
+use function count;
+use function file_exists;
+use function is_dir;
+use function is_writable;
+use function mkdir;
+use function realpath;
+use function sprintf;
 
 /**
  * Command to (re)generate the persistent collection classes used by doctrine.
  *
- * @since 1.1
  */
 class GeneratePersistentCollectionsCommand extends Console\Command\Command
 {
@@ -22,16 +31,19 @@ protected function configure()
         $this
             ->setName('odm:generate:persistent-collections')
             ->setDescription('Generates persistent collection classes for custom collections.')
-            ->setDefinition(array(
+            ->setDefinition([
                 new InputOption(
-                    'filter', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
+                    'filter',
+                    null,
+                    InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
                     'A string pattern used to match documents that should be processed.'
                 ),
                 new InputArgument(
-                    'dest-path', InputArgument::OPTIONAL,
+                    'dest-path',
+                    InputArgument::OPTIONAL,
                     'The path to generate your proxy classes. If none is provided, it will attempt to grab from configuration.'
                 ),
-            ))
+            ])
             ->setHelp(<<<EOT
 Generates persistent collection classes for custom collections.
 EOT
@@ -53,17 +65,17 @@ protected function execute(Console\Input\InputInterface $input, Console\Output\O
             $destPath = $dm->getConfiguration()->getPersistentCollectionDir();
         }
 
-        if ( ! is_dir($destPath)) {
+        if (! is_dir($destPath)) {
             mkdir($destPath, 0775, true);
         }
 
         $destPath = realpath($destPath);
 
-        if ( ! file_exists($destPath)) {
+        if (! file_exists($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Persistent collections destination directory '<info>%s</info>' does not exist.", $destPath)
             );
-        } elseif ( ! is_writable($destPath)) {
+        } elseif (! is_writable($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Persistent collections destination directory '<info>%s</info>' does not have write permissions.", $destPath)
             );
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateProxiesCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateProxiesCommand.php
index b5f650dc7c..043c3ba7a1 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateProxiesCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/GenerateProxiesCommand.php
@@ -1,17 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Tools\Console\MetadataFilter;
+use Symfony\Component\Console;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputOption;
-use Symfony\Component\Console;
-use Doctrine\ODM\MongoDB\Tools\Console\MetadataFilter;
+use const PHP_EOL;
+use function array_filter;
+use function count;
+use function file_exists;
+use function is_dir;
+use function is_writable;
+use function mkdir;
+use function realpath;
+use function sprintf;
 
 /**
  * Command to (re)generate the proxy classes used by doctrine.
  *
- * @since   1.0
  */
 class GenerateProxiesCommand extends Console\Command\Command
 {
@@ -23,16 +33,19 @@ protected function configure()
         $this
         ->setName('odm:generate:proxies')
         ->setDescription('Generates proxy classes for document classes.')
-        ->setDefinition(array(
+        ->setDefinition([
             new InputOption(
-                'filter', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
+                'filter',
+                null,
+                InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
                 'A string pattern used to match documents that should be processed.'
             ),
             new InputArgument(
-                'dest-path', InputArgument::OPTIONAL,
+                'dest-path',
+                InputArgument::OPTIONAL,
                 'The path to generate your proxy classes. If none is provided, it will attempt to grab from configuration.'
             ),
-        ))
+        ])
         ->setHelp(<<<EOT
 Generates proxy classes for document classes.
 EOT
@@ -45,9 +58,9 @@ protected function configure()
     protected function execute(Console\Input\InputInterface $input, Console\Output\OutputInterface $output)
     {
         $dm = $this->getHelper('documentManager')->getDocumentManager();
-        
+
         $metadatas = array_filter($dm->getMetadataFactory()->getAllMetadata(), function (ClassMetadata $classMetadata) {
-            return !$classMetadata->isEmbeddedDocument && !$classMetadata->isMappedSuperclass && !$classMetadata->isQueryResultDocument;
+            return ! $classMetadata->isEmbeddedDocument && ! $classMetadata->isMappedSuperclass && ! $classMetadata->isQueryResultDocument;
         });
         $metadatas = MetadataFilter::filter($metadatas, $input->getOption('filter'));
 
@@ -56,17 +69,17 @@ protected function execute(Console\Input\InputInterface $input, Console\Output\O
             $destPath = $dm->getConfiguration()->getProxyDir();
         }
 
-        if ( ! is_dir($destPath)) {
+        if (! is_dir($destPath)) {
             mkdir($destPath, 0775, true);
         }
 
         $destPath = realpath($destPath);
 
-        if ( ! file_exists($destPath)) {
+        if (! file_exists($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Proxies destination directory '<info>%s</info>' does not exist.", $destPath)
             );
-        } elseif ( ! is_writable($destPath)) {
+        } elseif (! is_writable($destPath)) {
             throw new \InvalidArgumentException(
                 sprintf("Proxies destination directory '<info>%s</info>' does not have write permissions.", $destPath)
             );
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/QueryCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/QueryCommand.php
index 3c65f500be..f4372b6919 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/QueryCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/QueryCommand.php
@@ -1,16 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command;
 
 use Doctrine\Common\Util\Debug;
+use Symfony\Component\Console;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputOption;
-use Symfony\Component\Console;
+use function is_numeric;
+use function json_decode;
 
 /**
  * Command to query mongodb and inspect the outputted results from your document classes.
  *
- * @since   1.0
  */
 class QueryCommand extends Console\Command\Command
 {
@@ -22,32 +25,43 @@ protected function configure()
         $this
         ->setName('odm:query')
         ->setDescription('Query mongodb and inspect the outputted results from your document classes.')
-        ->setDefinition(array(
+        ->setDefinition([
             new InputArgument(
-                'class', InputArgument::REQUIRED,
+                'class',
+                InputArgument::REQUIRED,
                 'The class to query.'
             ),
             new InputArgument(
-                'query', InputArgument::REQUIRED,
+                'query',
+                InputArgument::REQUIRED,
                 'The query to execute and output the results for.'
             ),
             new InputOption(
-                'hydrate', null, InputOption::VALUE_NONE,
+                'hydrate',
+                null,
+                InputOption::VALUE_NONE,
                 'Whether or not to hydrate the results in to document objects.'
             ),
             new InputOption(
-                'skip', null, InputOption::VALUE_REQUIRED,
+                'skip',
+                null,
+                InputOption::VALUE_REQUIRED,
                 'The number of documents to skip in the cursor.'
             ),
             new InputOption(
-                'limit', null, InputOption::VALUE_REQUIRED,
+                'limit',
+                null,
+                InputOption::VALUE_REQUIRED,
                 'The number of documents to return.'
             ),
             new InputOption(
-                'depth', null, InputOption::VALUE_REQUIRED,
-                'Dumping depth of Document graph.', 7
-            )
-        ))
+                'depth',
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Dumping depth of Document graph.',
+                7
+            ),
+        ])
         ->setHelp(<<<EOT
 Execute a query and output the results.
 EOT
@@ -66,12 +80,12 @@ protected function execute(Console\Input\InputInterface $input, Console\Output\O
 
         $depth = $input->getOption('depth');
 
-        if ( ! is_numeric($depth)) {
+        if (! is_numeric($depth)) {
             throw new \LogicException("Option 'depth' must contain an integer value");
         }
 
         if (($skip = $input->getOption('skip')) !== null) {
-            if ( ! is_numeric($skip)) {
+            if (! is_numeric($skip)) {
                 throw new \LogicException("Option 'skip' must contain an integer value");
             }
 
@@ -79,7 +93,7 @@ protected function execute(Console\Input\InputInterface $input, Console\Output\O
         }
 
         if (($limit = $input->getOption('limit')) !== null) {
-            if ( ! is_numeric($limit)) {
+            if (! is_numeric($limit)) {
                 throw new \LogicException("Option 'limit' must contain an integer value");
             }
 
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/AbstractCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/AbstractCommand.php
index d20bd4cda9..133bf00aef 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/AbstractCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/AbstractCommand.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
 
+use Doctrine\ODM\MongoDB\DocumentManager;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use Doctrine\ODM\MongoDB\SchemaManager;
 use Symfony\Component\Console\Command\Command;
 
 abstract class AbstractCommand extends Command
 {
-    const DB = 'db';
-    const COLLECTION = 'collection';
-    const INDEX = 'index';
+    public const DB = 'db';
+    public const COLLECTION = 'collection';
+    public const INDEX = 'index';
 
     abstract protected function processDocumentCollection(SchemaManager $sm, $document);
 
@@ -32,7 +36,7 @@ protected function getSchemaManager()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     protected function getDocumentManager()
     {
@@ -40,7 +44,7 @@ protected function getDocumentManager()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory
+     * @return ClassMetadataFactory
      */
     protected function getMetadataFactory()
     {
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/CreateCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/CreateCommand.php
index 521c407a53..f25f6d8cde 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/CreateCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/CreateCommand.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
@@ -7,10 +9,13 @@
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
+use function array_filter;
+use function sprintf;
+use function ucfirst;
 
 class CreateCommand extends AbstractCommand
 {
-    private $createOrder = array(self::COLLECTION, self::INDEX);
+    private $createOrder = [self::COLLECTION, self::INDEX];
 
     private $timeout;
 
@@ -53,10 +58,10 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $output->writeln(sprintf(
                     'Created <comment>%s%s</comment> for <info>%s</info>',
                     $option,
-                    (isset($class) ? (self::INDEX === $option ? '(es)' : '') : (self::INDEX === $option ? 'es' : 's')),
+                    (isset($class) ? ($option === self::INDEX ? '(es)' : '') : ($option === self::INDEX ? 'es' : 's')),
                     ($class ?? 'all classes')
                 ));
-            } catch (\Exception $e) {
+            } catch (\Throwable $e) {
                 $output->writeln('<error>' . $e->getMessage() . '</error>');
                 $isErrored = true;
             }
@@ -99,15 +104,15 @@ protected function processDocumentProxy(SchemaManager $sm, $document)
     {
         $classMetadata = $this->getMetadataFactory()->getMetadataFor($document);
 
-        if (!$classMetadata->isEmbeddedDocument && !$classMetadata->isMappedSuperclass && !$classMetadata->isQueryResultDocument) {
-            $this->getDocumentManager()->getProxyFactory()->generateProxyClasses(array($classMetadata));
+        if (! $classMetadata->isEmbeddedDocument && ! $classMetadata->isMappedSuperclass && ! $classMetadata->isQueryResultDocument) {
+            $this->getDocumentManager()->getProxyFactory()->generateProxyClasses([$classMetadata]);
         }
     }
 
     protected function processProxy(SchemaManager $sm)
     {
         $classes = array_filter($this->getMetadataFactory()->getAllMetadata(), function (ClassMetadata $classMetadata) {
-            return !$classMetadata->isEmbeddedDocument && !$classMetadata->isMappedSuperclass && !$classMetadata->isQueryResultDocument;
+            return ! $classMetadata->isEmbeddedDocument && ! $classMetadata->isMappedSuperclass && ! $classMetadata->isQueryResultDocument;
         });
 
         $this->getDocumentManager()->getProxyFactory()->generateProxyClasses($classes);
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/DropCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/DropCommand.php
index f5c099d418..e09d437dec 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/DropCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/DropCommand.php
@@ -1,15 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
 
 use Doctrine\ODM\MongoDB\SchemaManager;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
+use function array_filter;
+use function sprintf;
+use function ucfirst;
 
 class DropCommand extends AbstractCommand
 {
-    private $dropOrder = array(self::INDEX, self::COLLECTION, self::DB);
+    private $dropOrder = [self::INDEX, self::COLLECTION, self::DB];
 
     protected function configure()
     {
@@ -46,10 +51,10 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $output->writeln(sprintf(
                     'Dropped <comment>%s%s</comment> for <info>%s</info>',
                     $option,
-                    (isset($class) ? (self::INDEX === $option ? '(es)' : '') : (self::INDEX === $option ? 'es' : 's')),
+                    (isset($class) ? ($option === self::INDEX ? '(es)' : '') : ($option === self::INDEX ? 'es' : 's')),
                     ($class ?? 'all classes')
                 ));
-            } catch (\Exception $e) {
+            } catch (\Throwable $e) {
                 $output->writeln('<error>' . $e->getMessage() . '</error>');
                 $isErrored = true;
             }
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ShardCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ShardCommand.php
index e95921e122..be3d959209 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ShardCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ShardCommand.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
 
 use Doctrine\ODM\MongoDB\SchemaManager;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
+use function sprintf;
 
 class ShardCommand extends AbstractCommand
 {
@@ -19,8 +22,6 @@ protected function configure()
     }
 
     /**
-     * @param InputInterface $input
-     * @param OutputInterface $output
      * @return int|null|void
      */
     protected function execute(InputInterface $input, OutputInterface $output)
@@ -38,7 +39,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $this->processIndex($sm);
                 $output->writeln('Enabled sharding for <info>all classes</info>');
             }
-        } catch (\Exception $e) {
+        } catch (\Throwable $e) {
             $output->writeln('<error>' . $e->getMessage() . '</error>');
             $isErrored = true;
         }
@@ -47,7 +48,6 @@ protected function execute(InputInterface $input, OutputInterface $output)
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      */
     protected function processDocumentIndex(SchemaManager $sm, $document)
@@ -55,16 +55,12 @@ protected function processDocumentIndex(SchemaManager $sm, $document)
         $sm->ensureDocumentSharding($document);
     }
 
-    /**
-     * @param SchemaManager $sm
-     */
     protected function processIndex(SchemaManager $sm)
     {
         $sm->ensureSharding();
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      * @throws \BadMethodCallException
      */
@@ -74,7 +70,6 @@ protected function processDocumentCollection(SchemaManager $sm, $document)
     }
 
     /**
-     * @param SchemaManager $sm
      * @throws \BadMethodCallException
      */
     protected function processCollection(SchemaManager $sm)
@@ -83,7 +78,6 @@ protected function processCollection(SchemaManager $sm)
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      * @throws \BadMethodCallException
      */
@@ -93,7 +87,6 @@ protected function processDocumentDb(SchemaManager $sm, $document)
     }
 
     /**
-     * @param SchemaManager $sm
      * @throws \BadMethodCallException
      */
     protected function processDb(SchemaManager $sm)
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/UpdateCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/UpdateCommand.php
index fafd67ab16..bf177ba8f0 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/UpdateCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/UpdateCommand.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
 
 use Doctrine\ODM\MongoDB\SchemaManager;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
+use function sprintf;
 
 class UpdateCommand extends AbstractCommand
 {
@@ -22,8 +25,6 @@ protected function configure()
     }
 
     /**
-     * @param InputInterface $input
-     * @param OutputInterface $output
      * @return int|null|void
      */
     protected function execute(InputInterface $input, OutputInterface $output)
@@ -44,7 +45,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $this->processIndex($sm);
                 $output->writeln('Updated <comment>indexes</comment> for <info>all classes</info>');
             }
-        } catch (\Exception $e) {
+        } catch (\Throwable $e) {
             $output->writeln('<error>' . $e->getMessage() . '</error>');
             $isErrored = true;
         }
@@ -53,7 +54,6 @@ protected function execute(InputInterface $input, OutputInterface $output)
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      */
     protected function processDocumentIndex(SchemaManager $sm, $document)
@@ -61,16 +61,12 @@ protected function processDocumentIndex(SchemaManager $sm, $document)
         $sm->updateDocumentIndexes($document, $this->timeout);
     }
 
-    /**
-     * @param SchemaManager $sm
-     */
     protected function processIndex(SchemaManager $sm)
     {
         $sm->updateIndexes($this->timeout);
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      * @throws \BadMethodCallException
      */
@@ -80,7 +76,6 @@ protected function processDocumentCollection(SchemaManager $sm, $document)
     }
 
     /**
-     * @param SchemaManager $sm
      * @throws \BadMethodCallException
      */
     protected function processCollection(SchemaManager $sm)
@@ -89,7 +84,6 @@ protected function processCollection(SchemaManager $sm)
     }
 
     /**
-     * @param SchemaManager $sm
      * @param object $document
      * @throws \BadMethodCallException
      */
@@ -99,7 +93,6 @@ protected function processDocumentDb(SchemaManager $sm, $document)
     }
 
     /**
-     * @param SchemaManager $sm
      * @throws \BadMethodCallException
      */
     protected function processDb(SchemaManager $sm)
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ValidateCommand.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ValidateCommand.php
index 0fe1e3c907..144e3e2c1e 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ValidateCommand.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Command/Schema/ValidateCommand.php
@@ -1,53 +1,58 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
-
-use Doctrine\Common\Cache\VoidCache;
-use Doctrine\ODM\MongoDB\DocumentManager;
-use Symfony\Component\Console\Command\Command;
-use Symfony\Component\Console\Input\InputInterface;
-use Symfony\Component\Console\Output\OutputInterface;
-
-class ValidateCommand extends Command
-{
-    /**
-     * @see \Symfony\Component\Console\Command\Command
-     */
-    protected function configure()
-    {
-        $this
-            ->setName('odm:schema:validate')
-            ->setDescription('Validates if document mapping stays the same after serializing into cache.')
-            ->setDefinition(array())
-            ->setHelp(<<<EOT
-Validates if document mapping stays the same after serializing into cache.
-EOT
-            );
-    }
-
-    /**
-     * @see \Symfony\Component\Console\Command\Command
-     */
-    protected function execute(InputInterface $input, OutputInterface $output)
-    {
-        /** @var DocumentManager $dm */
-        $dm = $this->getHelper('documentManager')->getDocumentManager();
-        $metadataFactory = $dm->getMetadataFactory();
-        $metadataFactory->setCacheDriver(new VoidCache());
-
-        $errors = 0;
-        foreach ($metadataFactory->getAllMetadata() as $meta) {
-            if ($meta != unserialize(serialize($meta))) {
-                ++$errors;
-                $output->writeln(sprintf("%s has mapping issues.", $meta->name));
-            }
-        }
-        if ($errors) {
-            $output->writeln(sprintf('<error>%d document(s) have mapping issues.</error>', $errors));
-        } else {
-            $output->writeln('All documents are OK!');
-        }
-
-        return $errors ? 255 : 0;
-    }
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tools\Console\Command\Schema;
+
+use Doctrine\Common\Cache\VoidCache;
+use Doctrine\ODM\MongoDB\DocumentManager;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use function serialize;
+use function sprintf;
+use function unserialize;
+
+class ValidateCommand extends Command
+{
+    /**
+     * @see \Symfony\Component\Console\Command\Command
+     */
+    protected function configure()
+    {
+        $this
+            ->setName('odm:schema:validate')
+            ->setDescription('Validates if document mapping stays the same after serializing into cache.')
+            ->setDefinition([])
+            ->setHelp(<<<EOT
+Validates if document mapping stays the same after serializing into cache.
+EOT
+            );
+    }
+
+    /**
+     * @see \Symfony\Component\Console\Command\Command
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        /** @var DocumentManager $dm */
+        $dm = $this->getHelper('documentManager')->getDocumentManager();
+        $metadataFactory = $dm->getMetadataFactory();
+        $metadataFactory->setCacheDriver(new VoidCache());
+
+        $errors = 0;
+        foreach ($metadataFactory->getAllMetadata() as $meta) {
+            if ($meta !== unserialize(serialize($meta))) {
+                ++$errors;
+                $output->writeln(sprintf('%s has mapping issues.', $meta->name));
+            }
+        }
+        if ($errors) {
+            $output->writeln(sprintf('<error>%d document(s) have mapping issues.</error>', $errors));
+        } else {
+            $output->writeln('All documents are OK!');
+        }
+
+        return $errors ? 255 : 0;
+    }
+}
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/Helper/DocumentManagerHelper.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/Helper/DocumentManagerHelper.php
index 2bc2f4770b..e1f608ac1f 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/Helper/DocumentManagerHelper.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/Helper/DocumentManagerHelper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console\Helper;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -8,17 +10,11 @@
 /**
  * Symfony console component helper for accessing a DocumentManager instance.
  *
- * @since  1.0
  */
 class DocumentManagerHelper extends Helper
 {
     protected $dm;
 
-    /**
-     * Constructor.
-     *
-     * @param DocumentManager $dm
-     */
     public function __construct(DocumentManager $dm)
     {
         $this->dm = $dm;
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/Console/MetadataFilter.php b/lib/Doctrine/ODM/MongoDB/Tools/Console/MetadataFilter.php
index 6ba3a183e3..96a2d81221 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/Console/MetadataFilter.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/Console/MetadataFilter.php
@@ -1,18 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools\Console;
 
+use function count;
+use function iterator_to_array;
+use function strpos;
+
 /**
  * Used by CLI Tools to restrict entity-based commands to given patterns.
  *
- * @since       1.0
  */
 class MetadataFilter extends \FilterIterator implements \Countable
 {
     /**
      * Filter Metadatas by one or more filter options.
      *
-     * @param array $metadatas
+     * @param array        $metadatas
      * @param array|string $filter
      * @return array
      */
@@ -25,10 +30,9 @@ public static function filter(array $metadatas, $filter)
     /**
      * @var array
      */
-    private $_filter = array();
+    private $_filter = [];
 
     /**
-     * @param \ArrayIterator $metadata
      * @param array|string $filter
      */
     public function __construct(\ArrayIterator $metadata, $filter)
@@ -42,7 +46,7 @@ public function __construct(\ArrayIterator $metadata, $filter)
      */
     public function accept()
     {
-        if (count($this->_filter) == 0) {
+        if (count($this->_filter) === 0) {
             return true;
         }
 
diff --git a/lib/Doctrine/ODM/MongoDB/Tools/ResolveTargetDocumentListener.php b/lib/Doctrine/ODM/MongoDB/Tools/ResolveTargetDocumentListener.php
index 12985b10f8..912b9d1933 100644
--- a/lib/Doctrine/ODM/MongoDB/Tools/ResolveTargetDocumentListener.php
+++ b/lib/Doctrine/ODM/MongoDB/Tools/ResolveTargetDocumentListener.php
@@ -1,9 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tools;
 
 use Doctrine\ODM\MongoDB\Event\LoadClassMetadataEventArgs;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use function array_replace_recursive;
+use function ltrim;
 
 /**
  * ResolveTargetDocumentListener
@@ -15,27 +19,24 @@ class ResolveTargetDocumentListener
     /**
      * @var array
      */
-    private $resolveTargetDocuments = array();
+    private $resolveTargetDocuments = [];
 
     /**
      * Add a target-document class name to resolve to a new class name.
      *
      * @param string $originalDocument
      * @param string $newDocument
-     * @param array $mapping
-     * @return void
+     * @param array  $mapping
      */
     public function addResolveTargetDocument($originalDocument, $newDocument, array $mapping)
     {
-        $mapping['targetDocument'] = ltrim($newDocument, "\\");
-        $this->resolveTargetDocuments[ltrim($originalDocument, "\\")] = $mapping;
+        $mapping['targetDocument'] = ltrim($newDocument, '\\');
+        $this->resolveTargetDocuments[ltrim($originalDocument, '\\')] = $mapping;
     }
 
     /**
      * Process event and resolve new target document names.
      *
-     * @param LoadClassMetadataEventArgs $args
-     * @return void
      */
     public function loadClassMetadata(LoadClassMetadataEventArgs $args)
     {
@@ -49,7 +50,6 @@ public function loadClassMetadata(LoadClassMetadataEventArgs $args)
     }
 
     /**
-     * @param ClassMetadata $classMetadata
      * @param array $mapping
      */
     private function remapAssociation(ClassMetadata $classMetadata, array $mapping)
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataByteArrayType.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataByteArrayType.php
index b581b86fa2..5b57833d5b 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataByteArrayType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataByteArrayType.php
@@ -1,16 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for byte array data.
  *
  * Per the BSON specification, this sub-type is deprecated in favor of the
  * generic sub-type (BinDataType class).
  *
- * @since       1.0
  */
 class BinDataByteArrayType extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_OLD_BINARY;
+    protected $binDataType = Binary::TYPE_OLD_BINARY;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataCustomType.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataCustomType.php
index cad7621737..8fc696a750 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataCustomType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataCustomType.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for custom binary data.
  *
- * @since       1.0
  */
 class BinDataCustomType extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_USER_DEFINED;
+    protected $binDataType = Binary::TYPE_USER_DEFINED;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataFuncType.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataFuncType.php
index d71290305f..038993aec0 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataFuncType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataFuncType.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for function data.
  *
- * @since       1.0
  */
 class BinDataFuncType extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_FUNCTION;
+    protected $binDataType = Binary::TYPE_FUNCTION;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataMD5Type.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataMD5Type.php
index 3ec0cc3bc1..2979d55b4b 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataMD5Type.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataMD5Type.php
@@ -1,16 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for binary MD5 data.
  *
  * Note: This sub-type is intended to store binary MD5 data. Considering using
  * the basic string field type for storing hexadecimal MD5 strings.
  *
- * @since       1.0
  */
 class BinDataMD5Type extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_MD5;
+    protected $binDataType = Binary::TYPE_MD5;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataType.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataType.php
index 93864cc4c8..5203121962 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataType.php
@@ -1,21 +1,25 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+use function sprintf;
+
 /**
  * The BinData type for generic data.
  *
- * @since       1.0
  */
 class BinDataType extends Type
 {
     /**
      * Data type for binary data
      *
-     * @var integer
+     * @var int
      * @see http://bsonspec.org/#/specification
      */
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_GENERIC;
+    protected $binDataType = Binary::TYPE_GENERIC;
 
     public function convertToDatabaseValue($value)
     {
@@ -23,12 +27,12 @@ public function convertToDatabaseValue($value)
             return null;
         }
 
-        if ( ! $value instanceof \MongoDB\BSON\Binary) {
-            return new \MongoDB\BSON\Binary($value, $this->binDataType);
+        if (! $value instanceof Binary) {
+            return new Binary($value, $this->binDataType);
         }
 
         if ($value->getType() !== $this->binDataType) {
-            return new \MongoDB\BSON\Binary($value->getData(), $this->binDataType);
+            return new Binary($value->getData(), $this->binDataType);
         }
 
         return $value;
@@ -36,7 +40,7 @@ public function convertToDatabaseValue($value)
 
     public function convertToPHPValue($value)
     {
-        return $value !== null ? ($value instanceof \MongoDB\BSON\Binary ? $value->getData() : $value) : null;
+        return $value !== null ? ($value instanceof Binary ? $value->getData() : $value) : null;
     }
 
     public function closureToMongo()
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDRFC4122Type.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDRFC4122Type.php
index 6c2d3ce671..496fbb56f9 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDRFC4122Type.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDRFC4122Type.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for binary UUID data, which follows RFC 4122.
  *
- * @since       1.0
  */
 class BinDataUUIDRFC4122Type extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_UUID;
+    protected $binDataType = Binary::TYPE_UUID;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDType.php b/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDType.php
index c5e7569bf2..937a555d18 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BinDataUUIDType.php
@@ -1,16 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Binary;
+
 /**
  * The BinData type for binary UUID data.
  *
  * Per the BSON specification, this sub-type is deprecated in favor of the
  * RFC 4122 UUID sub-type (BinDataUUIDRFC4122Type class).
  *
- * @since       1.0
  */
 class BinDataUUIDType extends BinDataType
 {
-    protected $binDataType = \MongoDB\BSON\Binary::TYPE_OLD_UUID;
+    protected $binDataType = Binary::TYPE_OLD_UUID;
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/BooleanType.php b/lib/Doctrine/ODM/MongoDB/Types/BooleanType.php
index 3d9ea1db20..d56fa9674c 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/BooleanType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/BooleanType.php
@@ -1,22 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The Boolean type.
  *
- * @since       1.0
  */
 class BooleanType extends Type
 {
     public function convertToDatabaseValue($value)
     {
-        return $value !== null ? (boolean) $value : null;
+        return $value !== null ? (bool) $value : null;
     }
 
     public function convertToPHPValue($value)
     {
-        return $value !== null ? (boolean) $value : null;
+        return $value !== null ? (bool) $value : null;
     }
 
     public function closureToMongo()
diff --git a/lib/Doctrine/ODM/MongoDB/Types/ClosureToPHP.php b/lib/Doctrine/ODM/MongoDB/Types/ClosureToPHP.php
index 8ec7f8502d..a571067ff7 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/ClosureToPHP.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/ClosureToPHP.php
@@ -1,7 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use function sprintf;
+
 trait ClosureToPHP
 {
     /**
diff --git a/lib/Doctrine/ODM/MongoDB/Types/CollectionType.php b/lib/Doctrine/ODM/MongoDB/Types/CollectionType.php
index 42abe6a82b..a079578b01 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/CollectionType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/CollectionType.php
@@ -1,20 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 use Doctrine\ODM\MongoDB\MongoDBException;
+use function array_values;
+use function is_array;
 
 /**
  * The Collection type.
  *
- * @since       1.0
  */
 class CollectionType extends Type
 {
     public function convertToDatabaseValue($value)
     {
         if ($value !== null && ! is_array($value)) {
-            throw MongoDBException::invalidValueForType('Collection', array('array', 'null'), $value);
+            throw MongoDBException::invalidValueForType('Collection', ['array', 'null'], $value);
         }
         return $value !== null ? array_values($value) : null;
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/CustomIdType.php b/lib/Doctrine/ODM/MongoDB/Types/CustomIdType.php
index ecada66a92..cc30d27ad8 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/CustomIdType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/CustomIdType.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The Id type.
  *
- * @since       1.0
  */
 class CustomIdType extends Type
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Types/DateType.php b/lib/Doctrine/ODM/MongoDB/Types/DateType.php
index 63f2ed0dc8..33779f706e 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/DateType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/DateType.php
@@ -1,11 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\UTCDateTime;
+use function date_default_timezone_get;
+use function explode;
+use function get_class;
+use function gettype;
+use function is_numeric;
+use function is_scalar;
+use function is_string;
+use function sprintf;
+use function str_pad;
+use function strpos;
+
 /**
  * The Date type.
  *
- * @since       1.0
  */
 class DateType extends Type
 {
@@ -24,35 +37,37 @@ public static function getDateTime($value)
 
         if ($value instanceof \DateTimeInterface) {
             return $value;
-        } elseif ($value instanceof \MongoDB\BSON\UTCDateTime) {
+        } elseif ($value instanceof UTCDateTime) {
             $datetime = $value->toDateTime();
             $datetime->setTimezone(new \DateTimeZone(date_default_timezone_get()));
         } elseif (is_numeric($value)) {
             $seconds = $value;
+            $value = (string) $value;
             $microseconds = 0;
 
-            if (false !== strpos($value, '.')) {
+            if (strpos($value, '.') !== false) {
                 list($seconds, $microseconds) = explode('.', $value);
                 $microseconds = str_pad($microseconds, 6, '0'); // ensure microseconds
             }
 
-            $datetime = static::craftDateTime($seconds, $microseconds);
+            $datetime = static::craftDateTime((int) $seconds, $microseconds);
         } elseif (is_string($value)) {
             try {
                 $datetime = new \DateTime($value);
-            } catch (\Exception $e) {
+            } catch (\Throwable $e) {
                 $exception = $e;
             }
         }
 
         if ($datetime === false) {
-            throw new \InvalidArgumentException(sprintf('Could not convert %s to a date value', is_scalar($value) ? '"'.$value.'"' : gettype($value)), 0, $exception);
+            throw new \InvalidArgumentException(sprintf('Could not convert %s to a date value', is_scalar($value) ? '"' . $value . '"' : gettype($value)), 0, $exception);
         }
 
         return $datetime;
     }
 
-    private static function craftDateTime($seconds, $microseconds = 0)
+    // @todo fix typing for $microseconds
+    private static function craftDateTime(int $seconds, $microseconds = 0)
     {
         $datetime = new \DateTime();
         $datetime->setTimestamp($seconds);
@@ -65,13 +80,13 @@ private static function craftDateTime($seconds, $microseconds = 0)
 
     public function convertToDatabaseValue($value)
     {
-        if ($value === null || $value instanceof \MongoDB\BSON\UTCDateTime) {
+        if ($value === null || $value instanceof UTCDateTime) {
             return $value;
         }
 
         $datetime = static::getDateTime($value);
 
-        return new \MongoDB\BSON\UTCDateTime((int) $datetime->format('Uv'));
+        return new UTCDateTime((int) $datetime->format('Uv'));
     }
 
     public function convertToPHPValue($value)
@@ -85,11 +100,11 @@ public function convertToPHPValue($value)
 
     public function closureToMongo()
     {
-        return 'if ($value === null || $value instanceof \MongoDB\BSON\UTCDateTime) { $return = $value; } else { $datetime = \\'.get_class($this).'::getDateTime($value); $return = new \MongoDB\BSON\UTCDateTime((int) $datetime->format(\'Uv\')); }';
+        return 'if ($value === null || $value instanceof \MongoDB\BSON\UTCDateTime) { $return = $value; } else { $datetime = \\' . get_class($this) . '::getDateTime($value); $return = new \MongoDB\BSON\UTCDateTime((int) $datetime->format(\'Uv\')); }';
     }
 
     public function closureToPHP()
     {
-        return 'if ($value === null) { $return = null; } else { $return = \\'.get_class($this).'::getDateTime($value); }';
+        return 'if ($value === null) { $return = null; } else { $return = \\' . get_class($this) . '::getDateTime($value); }';
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/FileType.php b/lib/Doctrine/ODM/MongoDB/Types/FileType.php
index 5e3ca82e94..284351d1dc 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/FileType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/FileType.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The File type.
  *
- * @since       1.0
  */
 class FileType extends Type
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Types/FloatType.php b/lib/Doctrine/ODM/MongoDB/Types/FloatType.php
index 048d3e0b52..a70f3401c8 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/FloatType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/FloatType.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The Float type.
  *
- * @since       1.0
  */
 class FloatType extends Type
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Types/HashType.php b/lib/Doctrine/ODM/MongoDB/Types/HashType.php
index 02c6035bbc..00f2528102 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/HashType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/HashType.php
@@ -1,20 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 use Doctrine\ODM\MongoDB\MongoDBException;
+use function is_array;
 
 /**
  * The Hash type.
  *
- * @since       1.0
  */
 class HashType extends Type
 {
     public function convertToDatabaseValue($value)
     {
         if ($value !== null && ! is_array($value)) {
-            throw MongoDBException::invalidValueForType('Hash', array('array', 'null'), $value);
+            throw MongoDBException::invalidValueForType('Hash', ['array', 'null'], $value);
         }
         return $value !== null ? (object) $value : null;
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/IdType.php b/lib/Doctrine/ODM/MongoDB/Types/IdType.php
index 13e872fafd..88eb0a3f5a 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/IdType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/IdType.php
@@ -1,13 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\ObjectId;
 use MongoDB\Driver\Exception\InvalidArgumentException;
 
 /**
  * The Id type.
  *
- * @since       1.0
  */
 class IdType extends Type
 {
@@ -16,11 +18,11 @@ public function convertToDatabaseValue($value)
         if ($value === null) {
             return null;
         }
-        if ( ! $value instanceof \MongoDB\BSON\ObjectId) {
+        if (! $value instanceof ObjectId) {
             try {
-                $value = new \MongoDB\BSON\ObjectId($value);
+                $value = new ObjectId((string) $value);
             } catch (InvalidArgumentException $e) {
-                $value = new \MongoDB\BSON\ObjectId();
+                $value = new ObjectId();
             }
         }
         return $value;
@@ -28,7 +30,7 @@ public function convertToDatabaseValue($value)
 
     public function convertToPHPValue($value)
     {
-        return $value instanceof \MongoDB\BSON\ObjectId ? (string) $value : $value;
+        return $value instanceof ObjectId ? (string) $value : $value;
     }
 
     public function closureToMongo()
diff --git a/lib/Doctrine/ODM/MongoDB/Types/IntIdType.php b/lib/Doctrine/ODM/MongoDB/Types/IntIdType.php
index 03dbd423d4..fd8fbf083e 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/IntIdType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/IntIdType.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The Integer Id type.
  *
- * @since       1.0
  */
 class IntIdType extends IntType
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Types/IntType.php b/lib/Doctrine/ODM/MongoDB/Types/IntType.php
index 7be088fd4c..8eb53f89e9 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/IntType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/IntType.php
@@ -1,22 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * The Int type.
  *
- * @since       1.0
  */
 class IntType extends Type
 {
     public function convertToDatabaseValue($value)
     {
-        return $value !== null ? (integer) $value : null;
+        return $value !== null ? (int) $value : null;
     }
 
     public function convertToPHPValue($value)
     {
-        return $value !== null ? (integer) $value : null;
+        return $value !== null ? (int) $value : null;
     }
 
     public function closureToMongo()
diff --git a/lib/Doctrine/ODM/MongoDB/Types/KeyType.php b/lib/Doctrine/ODM/MongoDB/Types/KeyType.php
index ef67034f9e..74cd5a9160 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/KeyType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/KeyType.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\MaxKey;
+use MongoDB\BSON\MinKey;
+
 /**
  * The Key type.
  *
- * @since       1.0
  */
 class KeyType extends Type
 {
@@ -14,7 +18,7 @@ public function convertToDatabaseValue($value)
         if ($value === null) {
             return null;
         }
-        return $value ? new \MongoDB\BSON\MaxKey : new \MongoDB\BSON\MinKey;
+        return $value ? new MaxKey() : new MinKey();
     }
 
     public function convertToPHPValue($value)
@@ -22,6 +26,6 @@ public function convertToPHPValue($value)
         if ($value === null) {
             return null;
         }
-        return $value instanceof \MongoDB\BSON\MaxKey ? 1 : 0;
+        return $value instanceof MaxKey ? 1 : 0;
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/ObjectIdType.php b/lib/Doctrine/ODM/MongoDB/Types/ObjectIdType.php
index 228667c66f..cd33ca176b 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/ObjectIdType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/ObjectIdType.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\ObjectId;
+
 /**
  * The ObjectId type.
  *
- * @since       1.0
  */
 class ObjectIdType extends Type
 {
@@ -14,8 +17,8 @@ public function convertToDatabaseValue($value)
         if ($value === null) {
             return null;
         }
-        if ( ! $value instanceof \MongoDB\BSON\ObjectId) {
-            $value = new \MongoDB\BSON\ObjectId($value);
+        if (! $value instanceof ObjectId) {
+            $value = new ObjectId($value);
         }
         return $value;
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Types/RawType.php b/lib/Doctrine/ODM/MongoDB/Types/RawType.php
index d16334a92f..5fb9ba9ee0 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/RawType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/RawType.php
@@ -1,11 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 /**
  * Raw data type.
  *
- * @since       1.0
  */
 class RawType extends Type
 {
diff --git a/lib/Doctrine/ODM/MongoDB/Types/StringType.php b/lib/Doctrine/ODM/MongoDB/Types/StringType.php
index e18ad0f074..44e0f045ec 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/StringType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/StringType.php
@@ -1,17 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
+use MongoDB\BSON\Regex;
+
 /**
  * The String type.
  *
- * @since       1.0
  */
 class StringType extends Type
 {
     public function convertToDatabaseValue($value)
     {
-        return ($value === null || $value instanceof \MongoDB\BSON\Regex) ? $value : (string) $value;
+        return ($value === null || $value instanceof Regex) ? $value : (string) $value;
     }
 
     public function convertToPHPValue($value)
diff --git a/lib/Doctrine/ODM/MongoDB/Types/TimestampType.php b/lib/Doctrine/ODM/MongoDB/Types/TimestampType.php
index 389ed21446..8a4399e912 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/TimestampType.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/TimestampType.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 use MongoDB\BSON\Timestamp;
+use function explode;
+use function substr;
 
 /**
  * The Timestamp type.
  *
- * @since       1.0
  */
 class TimestampType extends Type
 {
@@ -26,7 +29,6 @@ public function convertToPHPValue($value)
     }
 
     /**
-     * @param Timestamp $timestamp
      * @return int
      */
     private function extractSeconds(Timestamp $timestamp)
diff --git a/lib/Doctrine/ODM/MongoDB/Types/Type.php b/lib/Doctrine/ODM/MongoDB/Types/Type.php
index 2206db17c3..2f2a7db860 100644
--- a/lib/Doctrine/ODM/MongoDB/Types/Type.php
+++ b/lib/Doctrine/ODM/MongoDB/Types/Type.php
@@ -1,46 +1,55 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Types;
 
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
 use Doctrine\ODM\MongoDB\Types;
+use MongoDB\BSON\ObjectId;
+use function end;
+use function explode;
+use function get_class;
+use function gettype;
+use function is_object;
+use function sprintf;
+use function str_replace;
 
 /**
  * The Type interface.
  *
- * @since       1.0
  */
 abstract class Type
 {
-    const ID = 'id';
-    const INTID = 'int_id';
-    const CUSTOMID = 'custom_id';
-    const BOOL = 'bool';
-    const BOOLEAN = 'boolean';
-    const INT = 'int';
-    const INTEGER = 'integer';
-    const FLOAT = 'float';
-    const STRING = 'string';
-    const DATE = 'date';
-    const KEY = 'key';
-    const TIMESTAMP = 'timestamp';
-    const BINDATA = 'bin';
-    const BINDATAFUNC = 'bin_func';
-    const BINDATABYTEARRAY = 'bin_bytearray';
-    const BINDATAUUID = 'bin_uuid';
-    const BINDATAUUIDRFC4122 = 'bin_uuid_rfc4122';
-    const BINDATAMD5 = 'bin_md5';
-    const BINDATACUSTOM = 'bin_custom';
-    const HASH = 'hash';
-    const COLLECTION = 'collection';
-    const OBJECTID = 'object_id';
-    const RAW = 'raw';
+    public const ID = 'id';
+    public const INTID = 'int_id';
+    public const CUSTOMID = 'custom_id';
+    public const BOOL = 'bool';
+    public const BOOLEAN = 'boolean';
+    public const INT = 'int';
+    public const INTEGER = 'integer';
+    public const FLOAT = 'float';
+    public const STRING = 'string';
+    public const DATE = 'date';
+    public const KEY = 'key';
+    public const TIMESTAMP = 'timestamp';
+    public const BINDATA = 'bin';
+    public const BINDATAFUNC = 'bin_func';
+    public const BINDATABYTEARRAY = 'bin_bytearray';
+    public const BINDATAUUID = 'bin_uuid';
+    public const BINDATAUUIDRFC4122 = 'bin_uuid_rfc4122';
+    public const BINDATAMD5 = 'bin_md5';
+    public const BINDATACUSTOM = 'bin_custom';
+    public const HASH = 'hash';
+    public const COLLECTION = 'collection';
+    public const OBJECTID = 'object_id';
+    public const RAW = 'raw';
 
     /** Map of already instantiated type objects. One instance per type (flyweight). */
-    private static $typeObjects = array();
+    private static $typeObjects = [];
 
     /** The map of supported doctrine mapping types. */
-    private static $typesMap = array(
+    private static $typesMap = [
         self::ID => Types\IdType::class,
         self::INTID => Types\IntIdType::class,
         self::CUSTOMID => Types\CustomIdType::class,
@@ -64,10 +73,12 @@ abstract class Type
         self::COLLECTION => Types\CollectionType::class,
         self::OBJECTID => Types\ObjectIdType::class,
         self::RAW => Types\RawType::class,
-    );
+    ];
 
     /* Prevent instantiation and force use of the factory method. */
-    final private function __construct() {}
+    final private function __construct()
+    {
+    }
 
     /**
      * Converts a value from its PHP representation to its database representation
@@ -106,7 +117,7 @@ public function closureToPHP()
     /**
      * Register a new type in the type map.
      *
-     * @param string $name The name of the type.
+     * @param string $name  The name of the type.
      * @param string $class The class name.
      */
     public static function registerType($name, $class)
@@ -123,12 +134,12 @@ public static function registerType($name, $class)
      */
     public static function getType($type)
     {
-        if ( ! isset(self::$typesMap[$type])) {
+        if (! isset(self::$typesMap[$type])) {
             throw new \InvalidArgumentException(sprintf('Invalid type specified "%s".', $type));
         }
-        if ( ! isset(self::$typeObjects[$type])) {
+        if (! isset(self::$typeObjects[$type])) {
             $className = self::$typesMap[$type];
-            self::$typeObjects[$type] = new $className;
+            self::$typeObjects[$type] = new $className();
         }
         return self::$typeObjects[$type];
     }
@@ -145,7 +156,7 @@ public static function getTypeFromPHPVariable($variable)
         if (is_object($variable)) {
             if ($variable instanceof \DateTimeInterface) {
                 return self::getType('date');
-            } elseif ($variable instanceof \MongoDB\BSON\ObjectId) {
+            } elseif ($variable instanceof ObjectId) {
                 return self::getType('id');
             }
         } else {
@@ -171,7 +182,7 @@ public static function convertPHPToDatabaseValue($value)
      * Adds a custom type to the type map.
      *
      * @static
-     * @param string $name Name of the type. This should correspond to what getName() returns.
+     * @param string $name      Name of the type. This should correspond to what getName() returns.
      * @param string $className The class name of the custom type.
      * @throws MappingException
      */
@@ -189,7 +200,7 @@ public static function addType($name, $className)
      *
      * @static
      * @param string $name Name of the type
-     * @return boolean TRUE if type is supported; FALSE otherwise
+     * @return bool TRUE if type is supported; FALSE otherwise
      */
     public static function hasType($name)
     {
@@ -206,7 +217,7 @@ public static function hasType($name)
      */
     public static function overrideType($name, $className)
     {
-        if ( ! isset(self::$typesMap[$name])) {
+        if (! isset(self::$typesMap[$name])) {
             throw MappingException::typeNotFound($name);
         }
 
diff --git a/lib/Doctrine/ODM/MongoDB/UnitOfWork.php b/lib/Doctrine/ODM/MongoDB/UnitOfWork.php
index 2c136a87ce..c066b26600 100644
--- a/lib/Doctrine/ODM/MongoDB/UnitOfWork.php
+++ b/lib/Doctrine/ODM/MongoDB/UnitOfWork.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -10,45 +12,58 @@
 use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
+use Doctrine\ODM\MongoDB\Persisters\CollectionPersister;
 use Doctrine\ODM\MongoDB\Persisters\PersistenceBuilder;
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Doctrine\ODM\MongoDB\Types\DateType;
 use Doctrine\ODM\MongoDB\Types\Type;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
 use Doctrine\ODM\MongoDB\Utility\LifecycleEventManager;
+use MongoDB\BSON\UTCDateTime;
+use function array_filter;
+use function count;
+use function get_class;
+use function in_array;
+use function is_array;
+use function is_object;
+use function method_exists;
+use function preg_match;
+use function serialize;
+use function spl_object_hash;
+use function sprintf;
 
 /**
  * The UnitOfWork is responsible for tracking changes to objects during an
  * "object-level" transaction and for writing out changes to the database
  * in the correct order.
  *
- * @since       1.0
  */
 class UnitOfWork implements PropertyChangedListener
 {
     /**
      * A document is in MANAGED state when its persistence is managed by a DocumentManager.
      */
-    const STATE_MANAGED = 1;
+    public const STATE_MANAGED = 1;
 
     /**
      * A document is new if it has just been instantiated (i.e. using the "new" operator)
      * and is not (yet) managed by a DocumentManager.
      */
-    const STATE_NEW = 2;
+    public const STATE_NEW = 2;
 
     /**
      * A detached document is an instance with a persistent identity that is not
      * (or no longer) associated with a DocumentManager (and a UnitOfWork).
      */
-    const STATE_DETACHED = 3;
+    public const STATE_DETACHED = 3;
 
     /**
      * A removed document instance is an instance with a persistent identity,
      * associated with a DocumentManager, whose persistent state has been
      * deleted (or is scheduled for deletion).
      */
-    const STATE_REMOVED = 4;
+    public const STATE_REMOVED = 4;
 
     /**
      * The identity map holds references to all managed documents.
@@ -64,7 +79,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $identityMap = array();
+    private $identityMap = [];
 
     /**
      * Map of all identifiers of managed documents.
@@ -72,7 +87,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $documentIdentifiers = array();
+    private $documentIdentifiers = [];
 
     /**
      * Map of the original document data of managed documents.
@@ -84,7 +99,7 @@ class UnitOfWork implements PropertyChangedListener
      *           A value will only really be copied if the value in the document is modified
      *           by the user.
      */
-    private $originalDocumentData = array();
+    private $originalDocumentData = [];
 
     /**
      * Map of document changes. Keys are object ids (spl_object_hash).
@@ -92,7 +107,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $documentChangeSets = array();
+    private $documentChangeSets = [];
 
     /**
      * The (cached) states of any known documents.
@@ -100,7 +115,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $documentStates = array();
+    private $documentStates = [];
 
     /**
      * Map of documents that are scheduled for dirty checking at commit time.
@@ -112,56 +127,56 @@ class UnitOfWork implements PropertyChangedListener
      * @var array
      * @todo rename: scheduledForSynchronization
      */
-    private $scheduledForDirtyCheck = array();
+    private $scheduledForDirtyCheck = [];
 
     /**
      * A list of all pending document insertions.
      *
      * @var array
      */
-    private $documentInsertions = array();
+    private $documentInsertions = [];
 
     /**
      * A list of all pending document updates.
      *
      * @var array
      */
-    private $documentUpdates = array();
+    private $documentUpdates = [];
 
     /**
      * A list of all pending document upserts.
      *
      * @var array
      */
-    private $documentUpserts = array();
+    private $documentUpserts = [];
 
     /**
      * A list of all pending document deletions.
      *
      * @var array
      */
-    private $documentDeletions = array();
+    private $documentDeletions = [];
 
     /**
      * All pending collection deletions.
      *
      * @var array
      */
-    private $collectionDeletions = array();
+    private $collectionDeletions = [];
 
     /**
      * All pending collection updates.
      *
      * @var array
      */
-    private $collectionUpdates = array();
+    private $collectionUpdates = [];
 
     /**
      * A list of documents related to collections scheduled for update or deletion
      *
      * @var array
      */
-    private $hasScheduledCollections = array();
+    private $hasScheduledCollections = [];
 
     /**
      * List of collections visited during changeset calculation on a commit-phase of a UnitOfWork.
@@ -170,7 +185,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $visitedCollections = array();
+    private $visitedCollections = [];
 
     /**
      * The DocumentManager that "owns" this UnitOfWork instance.
@@ -191,7 +206,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $orphanRemovals = array();
+    private $orphanRemovals = [];
 
     /**
      * The HydratorFactory used for hydrating array Mongo documents to Doctrine object documents.
@@ -205,7 +220,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $persisters = array();
+    private $persisters = [];
 
     /**
      * The collection persister instance used to persist changes to collections.
@@ -226,7 +241,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $parentAssociations = array();
+    private $parentAssociations = [];
 
     /**
      * @var LifecycleEventManager
@@ -240,7 +255,7 @@ class UnitOfWork implements PropertyChangedListener
      *
      * @var array
      */
-    private $embeddedDocumentsRegistry = array();
+    private $embeddedDocumentsRegistry = [];
 
     /**
      * @var int
@@ -250,9 +265,6 @@ class UnitOfWork implements PropertyChangedListener
     /**
      * Initializes a new UnitOfWork instance, bound to the given DocumentManager.
      *
-     * @param DocumentManager $dm
-     * @param EventManager $evm
-     * @param HydratorFactory $hydratorFactory
      */
     public function __construct(DocumentManager $dm, EventManager $evm, HydratorFactory $hydratorFactory)
     {
@@ -270,7 +282,7 @@ public function __construct(DocumentManager $dm, EventManager $evm, HydratorFact
      */
     public function getPersistenceBuilder()
     {
-        if ( ! $this->persistenceBuilder) {
+        if (! $this->persistenceBuilder) {
             $this->persistenceBuilder = new PersistenceBuilder($this->dm, $this);
         }
         return $this->persistenceBuilder;
@@ -280,7 +292,7 @@ public function getPersistenceBuilder()
      * Sets the parent association for a given embedded document.
      *
      * @param object $document
-     * @param array $mapping
+     * @param array  $mapping
      * @param object $parent
      * @param string $propertyPath
      */
@@ -288,7 +300,7 @@ public function setParentAssociation($document, $mapping, $parent, $propertyPath
     {
         $oid = spl_object_hash($document);
         $this->embeddedDocumentsRegistry[$oid] = $document;
-        $this->parentAssociations[$oid] = array($mapping, $parent, $propertyPath);
+        $this->parentAssociations[$oid] = [$mapping, $parent, $propertyPath];
     }
 
     /**
@@ -316,7 +328,7 @@ public function getParentAssociation($document)
      */
     public function getDocumentPersister($documentName)
     {
-        if ( ! isset($this->persisters[$documentName])) {
+        if (! isset($this->persisters[$documentName])) {
             $class = $this->dm->getClassMetadata($documentName);
             $pb = $this->getPersistenceBuilder();
             $this->persisters[$documentName] = new Persisters\DocumentPersister($pb, $this->dm, $this->evm, $this, $this->hydratorFactory, $class);
@@ -327,11 +339,11 @@ public function getDocumentPersister($documentName)
     /**
      * Get the collection persister instance.
      *
-     * @return \Doctrine\ODM\MongoDB\Persisters\CollectionPersister
+     * @return CollectionPersister
      */
     public function getCollectionPersister()
     {
-        if ( ! isset($this->collectionPersister)) {
+        if (! isset($this->collectionPersister)) {
             $pb = $this->getPersistenceBuilder();
             $this->collectionPersister = new Persisters\CollectionPersister($this->dm, $pb, $this);
         }
@@ -342,7 +354,6 @@ public function getCollectionPersister()
      * Set the document persister instance to use for the given document name
      *
      * @param string $documentName
-     * @param Persisters\DocumentPersister $persister
      */
     public function setDocumentPersister($documentName, Persisters\DocumentPersister $persister)
     {
@@ -362,7 +373,7 @@ public function setDocumentPersister($documentName, Persisters\DocumentPersister
      *
      * @param array $options Array of options to be used with batchInsert(), update() and remove()
      */
-    public function commit(array $options = array())
+    public function commit(array $options = [])
     {
         // Raise preFlush
         if ($this->evm->hasListeners(Events::preFlush)) {
@@ -372,7 +383,7 @@ public function commit(array $options = array())
         // Compute changes done since last commit.
         $this->computeChangeSets();
 
-        if ( ! ($this->documentInsertions ||
+        if (! ($this->documentInsertions ||
             $this->documentUpserts ||
             $this->documentDeletions ||
             $this->documentUpdates ||
@@ -435,7 +446,7 @@ public function commit(array $options = array())
             $this->visitedCollections =
             $this->scheduledForDirtyCheck =
             $this->orphanRemovals =
-            $this->hasScheduledCollections = array();
+            $this->hasScheduledCollections = [];
         } finally {
             $this->commitsInProgress--;
         }
@@ -444,17 +455,17 @@ public function commit(array $options = array())
     /**
      * Groups a list of scheduled documents by their class.
      *
-     * @param array $documents Scheduled documents (e.g. $this->documentInsertions)
-     * @param bool $includeEmbedded
+     * @param array $documents       Scheduled documents (e.g. $this->documentInsertions)
+     * @param bool  $includeEmbedded
      * @return array Tuples of ClassMetadata and a corresponding array of objects
      */
     private function getClassesForCommitAction($documents, $includeEmbedded = false)
     {
         if (empty($documents)) {
-            return array();
+            return [];
         }
-        $divided = array();
-        $embeds = array();
+        $divided = [];
+        $embeds = [];
         foreach ($documents as $oid => $d) {
             $className = get_class($d);
             if (isset($embeds[$className])) {
@@ -470,7 +481,7 @@ private function getClassesForCommitAction($documents, $includeEmbedded = false)
                 continue;
             }
             if (empty($divided[$class->name])) {
-                $divided[$class->name] = array($class, array($oid => $d));
+                $divided[$class->name] = [$class, [$oid => $d]];
             } else {
                 $divided[$class->name][1][$oid] = $d;
             }
@@ -487,7 +498,7 @@ private function computeScheduleInsertsChangeSets()
     {
         foreach ($this->documentInsertions as $document) {
             $class = $this->dm->getClassMetadata(get_class($document));
-            if ( ! $class->isEmbeddedDocument) {
+            if (! $class->isEmbeddedDocument) {
                 $this->computeChangeSet($class, $document);
             }
         }
@@ -502,7 +513,7 @@ private function computeScheduleUpsertsChangeSets()
     {
         foreach ($this->documentUpserts as $document) {
             $class = $this->dm->getClassMetadata(get_class($document));
-            if ( ! $class->isEmbeddedDocument) {
+            if (! $class->isEmbeddedDocument) {
                 $this->computeChangeSet($class, $document);
             }
         }
@@ -518,7 +529,7 @@ public function getDocumentChangeSet($document)
     {
         $oid = spl_object_hash($document);
 
-        return $this->documentChangeSets[$oid] ?? array();
+        return $this->documentChangeSets[$oid] ?? [];
     }
 
     /**
@@ -526,7 +537,7 @@ public function getDocumentChangeSet($document)
      * Sets the changeset for a document.
      *
      * @param object $document
-     * @param array $changeset
+     * @param array  $changeset
      */
     public function setDocumentChangeSet($document, $changeset)
     {
@@ -542,7 +553,7 @@ public function setDocumentChangeSet($document, $changeset)
     public function getDocumentActualData($document)
     {
         $class = $this->dm->getClassMetadata(get_class($document));
-        $actualData = array();
+        $actualData = [];
         foreach ($class->reflFields as $name => $refProp) {
             $mapping = $class->fieldMappings[$name];
             // skip not saved fields
@@ -553,14 +564,14 @@ public function getDocumentActualData($document)
             if ((isset($mapping['association']) && $mapping['type'] === 'many')
                 && $value !== null && ! ($value instanceof PersistentCollectionInterface)) {
                 // If $actualData[$name] is not a Collection then use an ArrayCollection.
-                if ( ! $value instanceof Collection) {
+                if (! $value instanceof Collection) {
                     $value = new ArrayCollection($value);
                 }
 
                 // Inject PersistentCollection
                 $coll = $this->dm->getConfiguration()->getPersistentCollectionFactory()->create($this->dm, $mapping, $value);
                 $coll->setOwner($document, $mapping);
-                $coll->setDirty( ! $value->isEmpty());
+                $coll->setDirty(! $value->isEmpty());
                 $class->reflFields[$name]->setValue($document, $coll);
                 $actualData[$name] = $coll;
             } else {
@@ -591,18 +602,18 @@ public function getDocumentActualData($document)
      * and any changes to its properties are detected, then a reference to the document is stored
      * there to mark it for an update.
      *
-     * @param ClassMetadata $class The class descriptor of the document.
-     * @param object $document The document for which to compute the changes.
+     * @param ClassMetadata $class    The class descriptor of the document.
+     * @param object        $document The document for which to compute the changes.
      */
     public function computeChangeSet(ClassMetadata $class, $document)
     {
-        if ( ! $class->isInheritanceTypeNone()) {
+        if (! $class->isInheritanceTypeNone()) {
             $class = $this->dm->getClassMetadata(get_class($document));
         }
 
         // Fire PreFlush lifecycle callbacks
-        if ( ! empty($class->lifecycleCallbacks[Events::preFlush])) {
-            $class->invokeLifecycleCallbacks(Events::preFlush, $document, array(new Event\PreFlushEventArgs($this->dm)));
+        if (! empty($class->lifecycleCallbacks[Events::preFlush])) {
+            $class->invokeLifecycleCallbacks(Events::preFlush, $document, [new Event\PreFlushEventArgs($this->dm)]);
         }
 
         $this->computeOrRecomputeChangeSet($class, $document);
@@ -611,9 +622,8 @@ public function computeChangeSet(ClassMetadata $class, $document)
     /**
      * Used to do the common work of computeChangeSet and recomputeSingleDocumentChangeSet
      *
-     * @param \Doctrine\ODM\MongoDB\Mapping\ClassMetadata $class
      * @param object $document
-     * @param boolean $recompute
+     * @param bool   $recompute
      */
     private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $recompute = false)
     {
@@ -624,7 +634,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
             // Document is either NEW or MANAGED but not yet fully persisted (only has an id).
             // These result in an INSERT.
             $this->originalDocumentData[$oid] = $actualData;
-            $changeSet = array();
+            $changeSet = [];
             foreach ($actualData as $propName => $actualValue) {
                 /* At this PersistentCollection shouldn't be here, probably it
                  * was cloned and its ownership must be fixed
@@ -637,7 +647,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
                 if (isset($class->fieldMappings[$propName]['reference']) && $class->fieldMappings[$propName]['isInverseSide']) {
                     continue;
                 }
-                $changeSet[$propName] = array(null, $actualValue);
+                $changeSet[$propName] = [null, $actualValue];
             }
             $this->documentChangeSets[$oid] = $changeSet;
         } else {
@@ -651,7 +661,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
             if ($isChangeTrackingNotify && ! $recompute && isset($this->documentChangeSets[$oid])) {
                 $changeSet = $this->documentChangeSets[$oid];
             } else {
-                $changeSet = array();
+                $changeSet = [];
             }
 
             foreach ($actualData as $propName => $actualValue) {
@@ -664,7 +674,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
 
                 // skip if value has not changed
                 if ($orgValue === $actualValue) {
-                    if (!$actualValue instanceof PersistentCollectionInterface) {
+                    if (! $actualValue instanceof PersistentCollectionInterface) {
                         continue;
                     }
 
@@ -679,7 +689,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
                     if ($orgValue !== null) {
                         $this->scheduleOrphanRemoval($orgValue);
                     }
-                    $changeSet[$propName] = array($orgValue, $actualValue);
+                    $changeSet[$propName] = [$orgValue, $actualValue];
                     continue;
                 }
 
@@ -689,7 +699,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
                         $this->scheduleOrphanRemoval($orgValue);
                     }
 
-                    $changeSet[$propName] = array($orgValue, $actualValue);
+                    $changeSet[$propName] = [$orgValue, $actualValue];
                     continue;
                 }
 
@@ -711,7 +721,7 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
 
                 // if embed-many or reference-many relationship
                 if (isset($class->fieldMappings[$propName]['type']) && $class->fieldMappings[$propName]['type'] === 'many') {
-                    $changeSet[$propName] = array($orgValue, $actualValue);
+                    $changeSet[$propName] = [$orgValue, $actualValue];
                     /* If original collection was exchanged with a non-empty value
                      * and $set will be issued, there is no need to $unset it first
                      */
@@ -726,17 +736,21 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
 
                 // skip equivalent date values
                 if (isset($class->fieldMappings[$propName]['type']) && $class->fieldMappings[$propName]['type'] === 'date') {
+                    /** @var DateType $dateType */
                     $dateType = Type::getType('date');
                     $dbOrgValue = $dateType->convertToDatabaseValue($orgValue);
                     $dbActualValue = $dateType->convertToDatabaseValue($actualValue);
 
-                    if ($dbOrgValue instanceof \MongoDB\BSON\UTCDateTime && $dbActualValue instanceof \MongoDB\BSON\UTCDateTime && $dbOrgValue == $dbActualValue) {
+                    $orgTimestamp = $dbOrgValue instanceof UTCDateTime ? $dbOrgValue->toDateTime()->getTimestamp() : null;
+                    $actualTimestamp = $dbActualValue instanceof UTCDateTime ? $dbActualValue->toDateTime()->getTimestamp() : null;
+
+                    if ($orgTimestamp === $actualTimestamp) {
                         continue;
                     }
                 }
 
                 // regular field
-                $changeSet[$propName] = array($orgValue, $actualValue);
+                $changeSet[$propName] = [$orgValue, $actualValue];
             }
             if ($changeSet) {
                 $this->documentChangeSets[$oid] = isset($this->documentChangeSets[$oid])
@@ -751,7 +765,9 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, $document, $r
         // Look for changes in associations of the document
         $associationMappings = array_filter(
             $class->associationMappings,
-            function ($assoc) { return empty($assoc['notSaved']); }
+            function ($assoc) {
+                return empty($assoc['notSaved']);
+            }
         );
 
         foreach ($associationMappings as $mapping) {
@@ -767,7 +783,7 @@ function ($assoc) { return empty($assoc['notSaved']); }
                 continue;
             }
 
-            $values = $mapping['type'] === ClassMetadata::ONE ? array($value) : $value->unwrap();
+            $values = $mapping['type'] === ClassMetadata::ONE ? [$value] : $value->unwrap();
 
             foreach ($values as $obj) {
                 $oid2 = spl_object_hash($obj);
@@ -776,10 +792,10 @@ function ($assoc) { return empty($assoc['notSaved']); }
                     if (empty($this->documentChangeSets[$oid][$mapping['fieldName']])) {
                         // instance of $value is the same as it was previously otherwise there would be
                         // change set already in place
-                        $this->documentChangeSets[$oid][$mapping['fieldName']] = array($value, $value);
+                        $this->documentChangeSets[$oid][$mapping['fieldName']] = [$value, $value];
                     }
 
-                    if ( ! $isNewDocument) {
+                    if (! $isNewDocument) {
                         $this->scheduleForUpdate($document);
                     }
 
@@ -823,8 +839,7 @@ public function computeChangeSets()
                     break;
 
                 default:
-                    $documentsToProcess = array();
-
+                    $documentsToProcess = [];
             }
 
             foreach ($documentsToProcess as $document) {
@@ -834,7 +849,7 @@ public function computeChangeSets()
                 }
                 // Only MANAGED documents that are NOT SCHEDULED FOR INSERTION, UPSERT OR DELETION are processed here.
                 $oid = spl_object_hash($document);
-                if ( ! isset($this->documentInsertions[$oid])
+                if (! isset($this->documentInsertions[$oid])
                     && ! isset($this->documentUpserts[$oid])
                     && ! isset($this->documentDeletions[$oid])
                     && isset($this->documentStates[$oid])
@@ -849,8 +864,8 @@ public function computeChangeSets()
      * Computes the changes of an association.
      *
      * @param object $parentDocument
-     * @param array $assoc
-     * @param mixed $value The value of the association.
+     * @param array  $assoc
+     * @param mixed  $value          The value of the association.
      * @throws \InvalidArgumentException
      */
     private function computeAssociationChanges($parentDocument, array $assoc, $value)
@@ -869,7 +884,7 @@ private function computeAssociationChanges($parentDocument, array $assoc, $value
             }
             $topmostOwner = $this->getOwningDocument($value->getOwner());
             $this->visitedCollections[spl_object_hash($topmostOwner)][] = $value;
-            if ( ! empty($assoc['orphanRemoval']) || isset($assoc['embedded'])) {
+            if (! empty($assoc['orphanRemoval']) || isset($assoc['embedded'])) {
                 $value->initialize();
                 foreach ($value->getDeletedDocuments() as $orphan) {
                     $this->scheduleOrphanRemoval($orphan);
@@ -880,13 +895,13 @@ private function computeAssociationChanges($parentDocument, array $assoc, $value
         // Look through the documents, and in any of their associations,
         // for transient (new) documents, recursively. ("Persistence by reachability")
         // Unwrap. Uninitialized collections will simply be empty.
-        $unwrappedValue = ($assoc['type'] === ClassMetadata::ONE) ? array($value) : $value->unwrap();
+        $unwrappedValue = ($assoc['type'] === ClassMetadata::ONE) ? [$value] : $value->unwrap();
 
         $count = 0;
         foreach ($unwrappedValue as $key => $entry) {
-            if ( ! is_object($entry)) {
+            if (! is_object($entry)) {
                 throw new \InvalidArgumentException(
-                        sprintf('Expected object, found "%s" in %s::%s', $entry, get_class($parentDocument), $assoc['name'])
+                    sprintf('Expected object, found "%s" in %s::%s', $entry, get_class($parentDocument), $assoc['name'])
                 );
             }
 
@@ -902,7 +917,7 @@ private function computeAssociationChanges($parentDocument, array $assoc, $value
 
             switch ($state) {
                 case self::STATE_NEW:
-                    if ( ! $assoc['isCascadePersist']) {
+                    if (! $assoc['isCascadePersist']) {
                         throw new \InvalidArgumentException('A new document was found through a relationship that was not'
                             . ' configured to cascade persist operations: ' . $this->objToStr($entry) . '.'
                             . ' Explicitly persist the new document or configure cascading persist operations'
@@ -954,7 +969,6 @@ private function computeAssociationChanges($parentDocument, array $assoc, $value
                 default:
                     // MANAGED associated documents are already taken into account
                     // during changeset calculation anyway, since they are in the identity map.
-
             }
         }
     }
@@ -969,8 +983,8 @@ private function computeAssociationChanges($parentDocument, array $assoc, $value
      * whereby changes detected in this method prevail.
      *
      * @ignore
-     * @param ClassMetadata $class The class descriptor of the document.
-     * @param object $document The document for which to (re)calculate the change set.
+     * @param ClassMetadata $class    The class descriptor of the document.
+     * @param object        $document The document for which to (re)calculate the change set.
      * @throws \InvalidArgumentException If the passed document is not MANAGED.
      */
     public function recomputeSingleDocumentChangeSet(ClassMetadata $class, $document)
@@ -982,11 +996,11 @@ public function recomputeSingleDocumentChangeSet(ClassMetadata $class, $document
 
         $oid = spl_object_hash($document);
 
-        if ( ! isset($this->documentStates[$oid]) || $this->documentStates[$oid] != self::STATE_MANAGED) {
+        if (! isset($this->documentStates[$oid]) || $this->documentStates[$oid] !== self::STATE_MANAGED) {
             throw new \InvalidArgumentException('Document must be managed.');
         }
 
-        if ( ! $class->isInheritanceTypeNone()) {
+        if (! $class->isInheritanceTypeNone()) {
             $class = $this->dm->getClassMetadata(get_class($document));
         }
 
@@ -994,7 +1008,6 @@ public function recomputeSingleDocumentChangeSet(ClassMetadata $class, $document
     }
 
     /**
-     * @param ClassMetadata $class
      * @param object $document
      * @throws \InvalidArgumentException If there is something wrong with document's identifier.
      */
@@ -1014,7 +1027,7 @@ private function persistNew(ClassMetadata $class, $document)
                 ));
             }
 
-            if ($class->generatorType === ClassMetadata::GENERATOR_TYPE_AUTO && $idValue !== null && ! preg_match('#^[0-9a-f]{24}$#', $idValue)) {
+            if ($class->generatorType === ClassMetadata::GENERATOR_TYPE_AUTO && $idValue !== null && ! preg_match('#^[0-9a-f]{24}$#', (string) $idValue)) {
                 throw new \InvalidArgumentException(sprintf(
                     '%s uses AUTO identifier generation strategy but provided identifier is not a valid ObjectId.',
                     get_class($document)
@@ -1045,11 +1058,10 @@ private function persistNew(ClassMetadata $class, $document)
     /**
      * Executes all document insertions for documents of the specified type.
      *
-     * @param ClassMetadata $class
      * @param array $documents Array of documents to insert
-     * @param array $options Array of options to be used with batchInsert()
+     * @param array $options   Array of options to be used with batchInsert()
      */
-    private function executeInserts(ClassMetadata $class, array $documents, array $options = array())
+    private function executeInserts(ClassMetadata $class, array $documents, array $options = [])
     {
         $persister = $this->getDocumentPersister($class->name);
 
@@ -1068,15 +1080,13 @@ private function executeInserts(ClassMetadata $class, array $documents, array $o
     /**
      * Executes all document upserts for documents of the specified type.
      *
-     * @param ClassMetadata $class
      * @param array $documents Array of documents to upsert
-     * @param array $options Array of options to be used with batchInsert()
+     * @param array $options   Array of options to be used with batchInsert()
      */
-    private function executeUpserts(ClassMetadata $class, array $documents, array $options = array())
+    private function executeUpserts(ClassMetadata $class, array $documents, array $options = [])
     {
         $persister = $this->getDocumentPersister($class->name);
 
-
         foreach ($documents as $oid => $document) {
             $persister->addUpsert($document);
             unset($this->documentUpserts[$oid]);
@@ -1092,11 +1102,10 @@ private function executeUpserts(ClassMetadata $class, array $documents, array $o
     /**
      * Executes all document updates for documents of the specified type.
      *
-     * @param Mapping\ClassMetadata $class
      * @param array $documents Array of documents to update
-     * @param array $options Array of options to be used with update()
+     * @param array $options   Array of options to be used with update()
      */
-    private function executeUpdates(ClassMetadata $class, array $documents, array $options = array())
+    private function executeUpdates(ClassMetadata $class, array $documents, array $options = [])
     {
         if ($class->isReadOnly) {
             return;
@@ -1108,7 +1117,7 @@ private function executeUpdates(ClassMetadata $class, array $documents, array $o
         foreach ($documents as $oid => $document) {
             $this->lifecycleEventManager->preUpdate($class, $document);
 
-            if ( ! empty($this->documentChangeSets[$oid]) || $this->hasScheduledCollections($document)) {
+            if (! empty($this->documentChangeSets[$oid]) || $this->hasScheduledCollections($document)) {
                 $persister->update($document, $options);
             }
 
@@ -1121,16 +1130,15 @@ private function executeUpdates(ClassMetadata $class, array $documents, array $o
     /**
      * Executes all document deletions for documents of the specified type.
      *
-     * @param ClassMetadata $class
      * @param array $documents Array of documents to delete
-     * @param array $options Array of options to be used with remove()
+     * @param array $options   Array of options to be used with remove()
      */
-    private function executeDeletions(ClassMetadata $class, array $documents, array $options = array())
+    private function executeDeletions(ClassMetadata $class, array $documents, array $options = [])
     {
         $persister = $this->getDocumentPersister($class->name);
 
         foreach ($documents as $oid => $document) {
-            if ( ! $class->isEmbeddedDocument) {
+            if (! $class->isEmbeddedDocument) {
                 $persister->delete($document, $options);
             }
             unset(
@@ -1163,7 +1171,6 @@ private function executeDeletions(ClassMetadata $class, array $documents, array
      * If the document already has an identifier, it will be added to the
      * identity map.
      *
-     * @param ClassMetadata $class
      * @param object $document The document to schedule for insertion.
      * @throws \InvalidArgumentException
      */
@@ -1192,7 +1199,6 @@ public function scheduleForInsert(ClassMetadata $class, $document)
      * Schedules a document for upsert into the database and adds it to the
      * identity map
      *
-     * @param ClassMetadata $class
      * @param object $document The document to schedule for upsert.
      * @throws \InvalidArgumentException
      */
@@ -1222,7 +1228,7 @@ public function scheduleForUpsert(ClassMetadata $class, $document)
      * Checks whether a document is scheduled for insertion.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isScheduledForInsert($document)
     {
@@ -1233,7 +1239,7 @@ public function isScheduledForInsert($document)
      * Checks whether a document is scheduled for upsert.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isScheduledForUpsert($document)
     {
@@ -1249,7 +1255,7 @@ public function isScheduledForUpsert($document)
     public function scheduleForUpdate($document)
     {
         $oid = spl_object_hash($document);
-        if ( ! isset($this->documentIdentifiers[$oid])) {
+        if (! isset($this->documentIdentifiers[$oid])) {
             throw new \InvalidArgumentException('Document has no identity.');
         }
 
@@ -1257,7 +1263,7 @@ public function scheduleForUpdate($document)
             throw new \InvalidArgumentException('Document is removed.');
         }
 
-        if ( ! isset($this->documentUpdates[$oid])
+        if (! isset($this->documentUpdates[$oid])
             && ! isset($this->documentInsertions[$oid])
             && ! isset($this->documentUpserts[$oid])) {
             $this->documentUpdates[$oid] = $document;
@@ -1270,7 +1276,7 @@ public function scheduleForUpdate($document)
      * at commit time.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isScheduledForUpdate($document)
     {
@@ -1301,7 +1307,7 @@ public function scheduleForDelete($document)
             return; // document has not been persisted yet, so nothing more to do.
         }
 
-        if ( ! $this->isInIdentityMap($document)) {
+        if (! $this->isInIdentityMap($document)) {
             return; // ignore
         }
 
@@ -1311,7 +1317,7 @@ public function scheduleForDelete($document)
         if (isset($this->documentUpdates[$oid])) {
             unset($this->documentUpdates[$oid]);
         }
-        if ( ! isset($this->documentDeletions[$oid])) {
+        if (! isset($this->documentDeletions[$oid])) {
             $this->documentDeletions[$oid] = $document;
         }
     }
@@ -1321,7 +1327,7 @@ public function scheduleForDelete($document)
      * of work.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isScheduledForDelete($document)
     {
@@ -1332,7 +1338,7 @@ public function isScheduledForDelete($document)
      * Checks whether a document is scheduled for insertion, update or deletion.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isDocumentScheduled($document)
     {
@@ -1352,8 +1358,8 @@ public function isDocumentScheduled($document)
      * keys to allow differentiation of equal, but not identical, values.
      *
      * @ignore
-     * @param object $document  The document to register.
-     * @return boolean  TRUE if the registration was successful, FALSE if the identity of
+     * @param object $document The document to register.
+     * @return bool  TRUE if the registration was successful, FALSE if the identity of
      *                  the document in question is already managed.
      */
     public function addToIdentityMap($document)
@@ -1379,10 +1385,10 @@ public function addToIdentityMap($document)
      * Gets the state of a document with regard to the current unit of work.
      *
      * @param object   $document
-     * @param int|null $assume The state to assume if the state is not yet known (not MANAGED or REMOVED).
-     *                         This parameter can be set to improve performance of document state detection
-     *                         by potentially avoiding a database lookup if the distinction between NEW and DETACHED
-     *                         is either known or does not matter for the caller of the method.
+     * @param int|null $assume   The state to assume if the state is not yet known (not MANAGED or REMOVED).
+     *                           This parameter can be set to improve performance of document state detection
+     *                           by potentially avoiding a database lookup if the distinction between NEW and DETACHED
+     *                           is either known or does not matter for the caller of the method.
      * @return int The document state.
      */
     public function getDocumentState($document, $assume = null)
@@ -1444,14 +1450,14 @@ public function getDocumentState($document, $assume = null)
      * @ignore
      * @param object $document
      * @throws \InvalidArgumentException
-     * @return boolean
+     * @return bool
      */
     public function removeFromIdentityMap($document)
     {
         $oid = spl_object_hash($document);
 
         // Check if id is registered first
-        if ( ! isset($this->documentIdentifiers[$oid])) {
+        if (! isset($this->documentIdentifiers[$oid])) {
             return false;
         }
 
@@ -1479,7 +1485,7 @@ public function removeFromIdentityMap($document)
      */
     public function getById($id, ClassMetadata $class)
     {
-        if ( ! $class->identifier) {
+        if (! $class->identifier) {
             throw new \InvalidArgumentException(sprintf('Class "%s" does not have an identifier', $class->name));
         }
 
@@ -1501,7 +1507,7 @@ public function getById($id, ClassMetadata $class)
      */
     public function tryGetById($id, ClassMetadata $class)
     {
-        if ( ! $class->identifier) {
+        if (! $class->identifier) {
             throw new \InvalidArgumentException(sprintf('Class "%s" does not have an identifier', $class->name));
         }
 
@@ -1526,13 +1532,13 @@ public function scheduleForDirtyCheck($document)
      * Checks whether a document is registered in the identity map.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function isInIdentityMap($document)
     {
         $oid = spl_object_hash($document);
 
-        if ( ! isset($this->documentIdentifiers[$oid])) {
+        if (! isset($this->documentIdentifiers[$oid])) {
             return false;
         }
 
@@ -1550,7 +1556,7 @@ private function getIdForIdentityMap($document)
     {
         $class = $this->dm->getClassMetadata(get_class($document));
 
-        if ( ! $class->identifier) {
+        if (! $class->identifier) {
             $id = spl_object_hash($document);
         } else {
             $id = $this->documentIdentifiers[spl_object_hash($document)];
@@ -1567,7 +1573,7 @@ private function getIdForIdentityMap($document)
      * @ignore
      * @param string $id
      * @param string $rootClassName
-     * @return boolean
+     * @return bool
      */
     public function containsId($id, $rootClassName)
     {
@@ -1587,7 +1593,7 @@ public function persist($document)
         if ($class->isMappedSuperclass || $class->isQueryResultDocument) {
             throw MongoDBException::cannotPersistMappedSuperclass($class->name);
         }
-        $visited = array();
+        $visited = [];
         $this->doPersist($document, $visited);
     }
 
@@ -1600,7 +1606,7 @@ public function persist($document)
      * this UnitOfWork as NEW.
      *
      * @param object $document The document to persist.
-     * @param array $visited The already visited documents.
+     * @param array  $visited  The already visited documents.
      * @throws \InvalidArgumentException
      * @throws MongoDBException
      */
@@ -1636,7 +1642,8 @@ private function doPersist($document, array &$visited)
 
             case self::STATE_DETACHED:
                 throw new \InvalidArgumentException(
-                    'Behavior of persist() for a detached document is not yet defined.');
+                    'Behavior of persist() for a detached document is not yet defined.'
+                );
 
             default:
                 throw MongoDBException::invalidDocumentState($documentState);
@@ -1652,7 +1659,7 @@ private function doPersist($document, array &$visited)
      */
     public function remove($document)
     {
-        $visited = array();
+        $visited = [];
         $this->doRemove($document, $visited);
     }
 
@@ -1663,7 +1670,7 @@ public function remove($document)
      * the already visited documents to prevent infinite recursions.
      *
      * @param object $document The document to delete.
-     * @param array $visited The map of the already visited documents.
+     * @param array  $visited  The map of the already visited documents.
      * @throws MongoDBException
      */
     private function doRemove($document, array &$visited)
@@ -1707,7 +1714,7 @@ private function doRemove($document, array &$visited)
      */
     public function merge($document)
     {
-        $visited = array();
+        $visited = [];
 
         return $this->doMerge($document, $visited);
     }
@@ -1784,7 +1791,7 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
                 $documentVersion = $class->reflFields[$class->versionField]->getValue($document);
 
                 // Throw exception if versions don't match
-                if ($managedCopyVersion != $documentVersion) {
+                if ($managedCopyVersion !== $documentVersion) {
                     throw LockException::lockFailedVersionMissmatch($document, $documentVersion, $managedCopyVersion);
                 }
             }
@@ -1793,8 +1800,8 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
             foreach ($class->reflClass->getProperties() as $prop) {
                 $name = $prop->name;
                 $prop->setAccessible(true);
-                if ( ! isset($class->associationMappings[$name])) {
-                    if ( ! $class->isIdentifier($name)) {
+                if (! isset($class->associationMappings[$name])) {
+                    if (! $class->isIdentifier($name)) {
                         $prop->setValue($managedCopy, $prop->getValue($document));
                     }
                 } else {
@@ -1808,7 +1815,7 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
                         } elseif ($other instanceof Proxy && ! $other->__isInitialized__) {
                             // Do not merge fields marked lazy that have not been fetched
                             continue;
-                        } elseif ( ! $assoc2['isCascadeMerge']) {
+                        } elseif (! $assoc2['isCascadeMerge']) {
                             if ($this->getDocumentState($other) === self::STATE_DETACHED) {
                                 $targetDocument = $assoc2['targetDocument'] ?? get_class($other);
                                 /* @var $targetClass \Doctrine\ODM\MongoDB\Mapping\ClassMetadata */
@@ -1821,8 +1828,8 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
                                     $other = $this
                                         ->dm
                                         ->getProxyFactory()
-                                        ->getProxy($assoc2['targetDocument'], array($targetClass->identifier => $relatedId));
-                                    $this->registerManaged($other, $relatedId, array());
+                                        ->getProxy($assoc2['targetDocument'], [$targetClass->identifier => $relatedId]);
+                                    $this->registerManaged($other, $relatedId, []);
                                 }
                             }
 
@@ -1841,7 +1848,7 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
 
                         $managedCol = $prop->getValue($managedCopy);
 
-                        if ( ! $managedCol) {
+                        if (! $managedCol) {
                             $managedCol = $this->dm->getConfiguration()->getPersistentCollectionFactory()->create($this->dm, $assoc2, null);
                             $managedCol->setOwner($managedCopy, $assoc2);
                             $prop->setValue($managedCopy, $managedCol);
@@ -1856,7 +1863,7 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
                             $managedCol->initialize();
 
                             // If $managedCol differs from the merged collection, clear and set dirty
-                            if ( ! $managedCol->isEmpty() && $managedCol !== $mergeCol) {
+                            if (! $managedCol->isEmpty() && $managedCol !== $mergeCol) {
                                 $managedCol->unwrap()->clear();
                                 $managedCol->setDirty(true);
 
@@ -1910,7 +1917,7 @@ private function doMerge($document, array &$visited, $prevManagedCopy = null, $a
      */
     public function detach($document)
     {
-        $visited = array();
+        $visited = [];
         $this->doDetach($document, $visited);
     }
 
@@ -1918,7 +1925,7 @@ public function detach($document)
      * Executes a detach operation on the given document.
      *
      * @param object $document
-     * @param array $visited
+     * @param array  $visited
      * @internal This method always considers documents with an assigned identifier as DETACHED.
      */
     private function doDetach($document, array &$visited)
@@ -1933,11 +1940,18 @@ private function doDetach($document, array &$visited)
         switch ($this->getDocumentState($document, self::STATE_DETACHED)) {
             case self::STATE_MANAGED:
                 $this->removeFromIdentityMap($document);
-                unset($this->documentInsertions[$oid], $this->documentUpdates[$oid],
-                    $this->documentDeletions[$oid], $this->documentIdentifiers[$oid],
-                    $this->documentStates[$oid], $this->originalDocumentData[$oid],
-                    $this->parentAssociations[$oid], $this->documentUpserts[$oid],
-                    $this->hasScheduledCollections[$oid], $this->embeddedDocumentsRegistry[$oid]);
+                unset(
+                    $this->documentInsertions[$oid],
+                    $this->documentUpdates[$oid],
+                    $this->documentDeletions[$oid],
+                    $this->documentIdentifiers[$oid],
+                    $this->documentStates[$oid],
+                    $this->originalDocumentData[$oid],
+                    $this->parentAssociations[$oid],
+                    $this->documentUpserts[$oid],
+                    $this->hasScheduledCollections[$oid],
+                    $this->embeddedDocumentsRegistry[$oid]
+                );
                 break;
             case self::STATE_NEW:
             case self::STATE_DETACHED:
@@ -1956,7 +1970,7 @@ private function doDetach($document, array &$visited)
      */
     public function refresh($document)
     {
-        $visited = array();
+        $visited = [];
         $this->doRefresh($document, $visited);
     }
 
@@ -1964,7 +1978,7 @@ public function refresh($document)
      * Executes a refresh operation on a document.
      *
      * @param object $document The document to refresh.
-     * @param array $visited The already visited documents during cascades.
+     * @param array  $visited  The already visited documents during cascades.
      * @throws \InvalidArgumentException If the document is not MANAGED.
      */
     private function doRefresh($document, array &$visited)
@@ -1978,8 +1992,8 @@ private function doRefresh($document, array &$visited)
 
         $class = $this->dm->getClassMetadata(get_class($document));
 
-        if ( ! $class->isEmbeddedDocument) {
-            if ($this->getDocumentState($document) == self::STATE_MANAGED) {
+        if (! $class->isEmbeddedDocument) {
+            if ($this->getDocumentState($document) === self::STATE_MANAGED) {
                 $this->getDocumentPersister($class->name)->refresh($document);
             } else {
                 throw new \InvalidArgumentException('Document is not MANAGED.');
@@ -1993,7 +2007,7 @@ private function doRefresh($document, array &$visited)
      * Cascades a refresh operation to associated documents.
      *
      * @param object $document
-     * @param array $visited
+     * @param array  $visited
      */
     private function cascadeRefresh($document, array &$visited)
     {
@@ -2001,7 +2015,9 @@ private function cascadeRefresh($document, array &$visited)
 
         $associationMappings = array_filter(
             $class->associationMappings,
-            function ($assoc) { return $assoc['isCascadeRefresh']; }
+            function ($assoc) {
+                return $assoc['isCascadeRefresh'];
+            }
         );
 
         foreach ($associationMappings as $mapping) {
@@ -2024,13 +2040,13 @@ function ($assoc) { return $assoc['isCascadeRefresh']; }
      * Cascades a detach operation to associated documents.
      *
      * @param object $document
-     * @param array $visited
+     * @param array  $visited
      */
     private function cascadeDetach($document, array &$visited)
     {
         $class = $this->dm->getClassMetadata(get_class($document));
         foreach ($class->fieldMappings as $mapping) {
-            if ( ! $mapping['isCascadeDetach']) {
+            if (! $mapping['isCascadeDetach']) {
                 continue;
             }
             $relatedDocuments = $class->reflFields[$mapping['fieldName']]->getValue($document);
@@ -2052,7 +2068,7 @@ private function cascadeDetach($document, array &$visited)
      *
      * @param object $document
      * @param object $managedCopy
-     * @param array $visited
+     * @param array  $visited
      */
     private function cascadeMerge($document, $managedCopy, array &$visited)
     {
@@ -2060,7 +2076,9 @@ private function cascadeMerge($document, $managedCopy, array &$visited)
 
         $associationMappings = array_filter(
             $class->associationMappings,
-            function ($assoc) { return $assoc['isCascadeMerge']; }
+            function ($assoc) {
+                return $assoc['isCascadeMerge'];
+            }
         );
 
         foreach ($associationMappings as $assoc) {
@@ -2085,7 +2103,7 @@ function ($assoc) { return $assoc['isCascadeMerge']; }
      * Cascades the save operation to associated documents.
      *
      * @param object $document
-     * @param array $visited
+     * @param array  $visited
      */
     private function cascadePersist($document, array &$visited)
     {
@@ -2093,7 +2111,9 @@ private function cascadePersist($document, array &$visited)
 
         $associationMappings = array_filter(
             $class->associationMappings,
-            function ($assoc) { return $assoc['isCascadePersist']; }
+            function ($assoc) {
+                return $assoc['isCascadePersist'];
+            }
         );
 
         foreach ($associationMappings as $fieldName => $mapping) {
@@ -2110,7 +2130,7 @@ function ($assoc) { return $assoc['isCascadePersist']; }
 
                 $count = 0;
                 foreach ($relatedDocuments as $relatedKey => $relatedDocument) {
-                    if ( ! empty($mapping['embedded'])) {
+                    if (! empty($mapping['embedded'])) {
                         list(, $knownParent, ) = $this->getParentAssociation($relatedDocument);
                         if ($knownParent && $knownParent !== $document) {
                             $relatedDocument = clone $relatedDocument;
@@ -2122,7 +2142,7 @@ function ($assoc) { return $assoc['isCascadePersist']; }
                     $this->doPersist($relatedDocument, $visited);
                 }
             } elseif ($relatedDocuments !== null) {
-                if ( ! empty($mapping['embedded'])) {
+                if (! empty($mapping['embedded'])) {
                     list(, $knownParent, ) = $this->getParentAssociation($relatedDocuments);
                     if ($knownParent && $knownParent !== $document) {
                         $relatedDocuments = clone $relatedDocuments;
@@ -2139,13 +2159,13 @@ function ($assoc) { return $assoc['isCascadePersist']; }
      * Cascades the delete operation to associated documents.
      *
      * @param object $document
-     * @param array $visited
+     * @param array  $visited
      */
     private function cascadeRemove($document, array &$visited)
     {
         $class = $this->dm->getClassMetadata(get_class($document));
         foreach ($class->fieldMappings as $mapping) {
-            if ( ! $mapping['isCascadeRemove']) {
+            if (! $mapping['isCascadeRemove']) {
                 continue;
             }
             if ($document instanceof Proxy && ! $document->__isInitialized__) {
@@ -2168,32 +2188,32 @@ private function cascadeRemove($document, array &$visited)
      * Acquire a lock on the given document.
      *
      * @param object $document
-     * @param int $lockMode
-     * @param int $lockVersion
+     * @param int    $lockMode
+     * @param int    $lockVersion
      * @throws LockException
      * @throws \InvalidArgumentException
      */
     public function lock($document, $lockMode, $lockVersion = null)
     {
-        if ($this->getDocumentState($document) != self::STATE_MANAGED) {
+        if ($this->getDocumentState($document) !== self::STATE_MANAGED) {
             throw new \InvalidArgumentException('Document is not MANAGED.');
         }
 
         $documentName = get_class($document);
         $class = $this->dm->getClassMetadata($documentName);
 
-        if ($lockMode == LockMode::OPTIMISTIC) {
-            if ( ! $class->isVersioned) {
+        if ($lockMode === LockMode::OPTIMISTIC) {
+            if (! $class->isVersioned) {
                 throw LockException::notVersioned($documentName);
             }
 
-            if ($lockVersion != null) {
+            if ($lockVersion !== null) {
                 $documentVersion = $class->reflFields[$class->versionField]->getValue($document);
-                if ($documentVersion != $lockVersion) {
+                if ($documentVersion !== $lockVersion) {
                     throw LockException::lockFailedVersionMissmatch($document, $lockVersion, $documentVersion);
                 }
             }
-        } elseif (in_array($lockMode, array(LockMode::PESSIMISTIC_READ, LockMode::PESSIMISTIC_WRITE))) {
+        } elseif (in_array($lockMode, [LockMode::PESSIMISTIC_READ, LockMode::PESSIMISTIC_WRITE])) {
             $this->getDocumentPersister($class->name)->lock($document, $lockMode);
         }
     }
@@ -2206,8 +2226,8 @@ public function lock($document, $lockMode, $lockVersion = null)
      */
     public function unlock($document)
     {
-        if ($this->getDocumentState($document) != self::STATE_MANAGED) {
-            throw new \InvalidArgumentException("Document is not MANAGED.");
+        if ($this->getDocumentState($document) !== self::STATE_MANAGED) {
+            throw new \InvalidArgumentException('Document is not MANAGED.');
         }
         $documentName = get_class($document);
         $this->getDocumentPersister($documentName)->unlock($document);
@@ -2236,9 +2256,9 @@ public function clear($documentName = null)
             $this->parentAssociations =
             $this->embeddedDocumentsRegistry =
             $this->orphanRemovals =
-            $this->hasScheduledCollections = array();
+            $this->hasScheduledCollections = [];
         } else {
-            $visited = array();
+            $visited = [];
             foreach ($this->identityMap as $className => $documents) {
                 if ($className === $documentName) {
                     foreach ($documents as $document) {
@@ -2289,9 +2309,7 @@ public function unscheduleOrphanRemoval($document)
      *  3) NOP if state is OK
      * Returned collection should be used from now on (only important with 2nd point)
      *
-     * @param PersistentCollectionInterface $coll
      * @param object $document
-     * @param ClassMetadata $class
      * @param string $propName
      * @return PersistentCollectionInterface
      */
@@ -2301,7 +2319,7 @@ private function fixPersistentCollectionOwnership(PersistentCollectionInterface
         if ($owner === null) { // cloned
             $coll->setOwner($document, $class->fieldMappings[$propName]);
         } elseif ($owner !== $document) { // no clone, we have to fix
-            if ( ! $coll->isInitialized()) {
+            if (! $coll->isInitialized()) {
                 $coll->initialize(); // we have to do this otherwise the cols share state
             }
             $newValue = clone $coll;
@@ -2320,13 +2338,12 @@ private function fixPersistentCollectionOwnership(PersistentCollectionInterface
      * INTERNAL:
      * Schedules a complete collection for removal when this UnitOfWork commits.
      *
-     * @param PersistentCollectionInterface $coll
      */
     public function scheduleCollectionDeletion(PersistentCollectionInterface $coll)
     {
         $oid = spl_object_hash($coll);
         unset($this->collectionUpdates[$oid]);
-        if ( ! isset($this->collectionDeletions[$oid])) {
+        if (! isset($this->collectionDeletions[$oid])) {
             $this->collectionDeletions[$oid] = $coll;
             $this->scheduleCollectionOwner($coll);
         }
@@ -2335,8 +2352,7 @@ public function scheduleCollectionDeletion(PersistentCollectionInterface $coll)
     /**
      * Checks whether a PersistentCollection is scheduled for deletion.
      *
-     * @param PersistentCollectionInterface $coll
-     * @return boolean
+     * @return bool
      */
     public function isCollectionScheduledForDeletion(PersistentCollectionInterface $coll)
     {
@@ -2347,7 +2363,6 @@ public function isCollectionScheduledForDeletion(PersistentCollectionInterface $
      * INTERNAL:
      * Unschedules a collection from being deleted when this UnitOfWork commits.
      *
-     * @param PersistentCollectionInterface $coll
      */
     public function unscheduleCollectionDeletion(PersistentCollectionInterface $coll)
     {
@@ -2363,7 +2378,6 @@ public function unscheduleCollectionDeletion(PersistentCollectionInterface $coll
      * INTERNAL:
      * Schedules a collection for update when this UnitOfWork commits.
      *
-     * @param PersistentCollectionInterface $coll
      */
     public function scheduleCollectionUpdate(PersistentCollectionInterface $coll)
     {
@@ -2375,7 +2389,7 @@ public function scheduleCollectionUpdate(PersistentCollectionInterface $coll)
             $this->unscheduleCollectionDeletion($coll);
         }
         $oid = spl_object_hash($coll);
-        if ( ! isset($this->collectionUpdates[$oid])) {
+        if (! isset($this->collectionUpdates[$oid])) {
             $this->collectionUpdates[$oid] = $coll;
             $this->scheduleCollectionOwner($coll);
         }
@@ -2385,7 +2399,6 @@ public function scheduleCollectionUpdate(PersistentCollectionInterface $coll)
      * INTERNAL:
      * Unschedules a collection from being updated when this UnitOfWork commits.
      *
-     * @param PersistentCollectionInterface $coll
      */
     public function unscheduleCollectionUpdate(PersistentCollectionInterface $coll)
     {
@@ -2400,8 +2413,7 @@ public function unscheduleCollectionUpdate(PersistentCollectionInterface $coll)
     /**
      * Checks whether a PersistentCollection is scheduled for update.
      *
-     * @param PersistentCollectionInterface $coll
-     * @return boolean
+     * @return bool
      */
     public function isCollectionScheduledForUpdate(PersistentCollectionInterface $coll)
     {
@@ -2420,7 +2432,7 @@ public function getVisitedCollections($document)
     {
         $oid = spl_object_hash($document);
 
-        return $this->visitedCollections[$oid] ?? array();
+        return $this->visitedCollections[$oid] ?? [];
     }
 
     /**
@@ -2434,7 +2446,7 @@ public function getScheduledCollections($document)
     {
         $oid = spl_object_hash($document);
 
-        return $this->hasScheduledCollections[$oid] ?? array();
+        return $this->hasScheduledCollections[$oid] ?? [];
     }
 
     /**
@@ -2442,7 +2454,7 @@ public function getScheduledCollections($document)
      * scheduled for update or deletion.
      *
      * @param object $document
-     * @return boolean
+     * @return bool
      */
     public function hasScheduledCollections($document)
     {
@@ -2460,7 +2472,6 @@ public function hasScheduledCollections($document)
      * unscheduled and atomic one is scheduled for update instead. This makes
      * calculating update data way easier.
      *
-     * @param PersistentCollectionInterface $coll
      */
     private function scheduleCollectionOwner(PersistentCollectionInterface $coll)
     {
@@ -2470,7 +2481,7 @@ private function scheduleCollectionOwner(PersistentCollectionInterface $coll)
         if ($document !== $coll->getOwner()) {
             $parent = $coll->getOwner();
             $mapping = [];
-            while (null !== ($parentAssoc = $this->getParentAssociation($parent))) {
+            while (($parentAssoc = $this->getParentAssociation($parent)) !== null) {
                 list($mapping, $parent, ) = $parentAssoc;
             }
             if (CollectionHelper::isAtomic($mapping['strategy'])) {
@@ -2482,7 +2493,7 @@ private function scheduleCollectionOwner(PersistentCollectionInterface $coll)
             }
         }
 
-        if ( ! $this->isDocumentScheduled($document)) {
+        if (! $this->isDocumentScheduled($document)) {
             $this->scheduleForUpdate($document);
         }
     }
@@ -2504,7 +2515,7 @@ public function getOwningDocument($document)
         while ($class->isEmbeddedDocument) {
             $parentAssociation = $this->getParentAssociation($document);
 
-            if ( ! $parentAssociation) {
+            if (! $parentAssociation) {
                 throw new \UnexpectedValueException('Could not determine parent association for ' . get_class($document));
             }
 
@@ -2560,13 +2571,13 @@ public function getClassNameForAssociation(array $mapping, $data)
      *
      * @ignore
      * @param string $className The name of the document class.
-     * @param array $data The data for the document.
-     * @param array $hints Any hints to account for during reconstitution/lookup of the document.
-     * @param object $document The document to be hydrated into in case of creation
+     * @param array  $data      The data for the document.
+     * @param array  $hints     Any hints to account for during reconstitution/lookup of the document.
+     * @param object $document  The document to be hydrated into in case of creation
      * @return object The document instance.
      * @internal Highly performance-sensitive method.
      */
-    public function getOrCreateDocument($className, $data, &$hints = array(), $document = null)
+    public function getOrCreateDocument($className, $data, &$hints = [], $document = null)
     {
         $class = $this->dm->getClassMetadata($className);
 
@@ -2672,12 +2683,9 @@ public function getOriginalDocumentData($document)
     {
         $oid = spl_object_hash($document);
 
-        return $this->originalDocumentData[$oid] ?? array();
+        return $this->originalDocumentData[$oid] ?? [];
     }
 
-    /**
-     * @ignore
-     */
     public function setOriginalDocumentData($document, array $data)
     {
         $oid = spl_object_hash($document);
@@ -2692,7 +2700,7 @@ public function setOriginalDocumentData($document, array $data)
      * @ignore
      * @param string $oid
      * @param string $property
-     * @param mixed $value
+     * @param mixed  $value
      */
     public function setOriginalDocumentProperty($oid, $property, $value)
     {
@@ -2713,7 +2721,7 @@ public function getDocumentIdentifier($document)
     /**
      * Checks whether the UnitOfWork has any pending insertions.
      *
-     * @return boolean TRUE if this UnitOfWork has pending insertions, FALSE otherwise.
+     * @return bool TRUE if this UnitOfWork has pending insertions, FALSE otherwise.
      */
     public function hasPendingInsertions()
     {
@@ -2724,7 +2732,7 @@ public function hasPendingInsertions()
      * Calculates the size of the UnitOfWork. The size of the UnitOfWork is the
      * number of documents in the identity map.
      *
-     * @return integer
+     * @return int
      */
     public function size()
     {
@@ -2747,15 +2755,15 @@ public function size()
      * conversion and throw an exception if it's inconsistent.
      *
      * @param object $document The document.
-     * @param array $id The identifier values.
-     * @param array $data The original document data.
+     * @param array  $id       The identifier values.
+     * @param array  $data     The original document data.
      */
     public function registerManaged($document, $id, $data)
     {
         $oid = spl_object_hash($document);
         $class = $this->dm->getClassMetadata(get_class($document));
 
-        if ( ! $class->identifier || $id === null) {
+        if (! $class->identifier || $id === null) {
             $this->documentIdentifiers[$oid] = $oid;
         } else {
             $this->documentIdentifiers[$oid] = $class->getPHPIdentifierValue($id);
@@ -2774,7 +2782,7 @@ public function registerManaged($document, $id, $data)
      */
     public function clearDocumentChangeSet($oid)
     {
-        $this->documentChangeSets[$oid] = array();
+        $this->documentChangeSets[$oid] = [];
     }
 
     /* PropertyChangedListener implementation */
@@ -2782,23 +2790,23 @@ public function clearDocumentChangeSet($oid)
     /**
      * Notifies this UnitOfWork of a property change in a document.
      *
-     * @param object $document The document that owns the property.
+     * @param object $document     The document that owns the property.
      * @param string $propertyName The name of the property that changed.
-     * @param mixed $oldValue The old value of the property.
-     * @param mixed $newValue The new value of the property.
+     * @param mixed  $oldValue     The old value of the property.
+     * @param mixed  $newValue     The new value of the property.
      */
     public function propertyChanged($document, $propertyName, $oldValue, $newValue)
     {
         $oid = spl_object_hash($document);
         $class = $this->dm->getClassMetadata(get_class($document));
 
-        if ( ! isset($class->fieldMappings[$propertyName])) {
+        if (! isset($class->fieldMappings[$propertyName])) {
             return; // ignore non-persistent fields
         }
 
         // Update changeset and mark document for synchronization
-        $this->documentChangeSets[$oid][$propertyName] = array($oldValue, $newValue);
-        if ( ! isset($this->scheduledForDirtyCheck[$class->name][$oid])) {
+        $this->documentChangeSets[$oid][$propertyName] = [$oldValue, $newValue];
+        if (! isset($this->scheduledForDirtyCheck[$class->name][$oid])) {
             $this->scheduleForDirtyCheck($document);
         }
     }
@@ -2867,7 +2875,6 @@ public function getScheduledCollectionUpdates()
      * Helper method to initialize a lazy loading proxy or persistent collection.
      *
      * @param object $obj
-     * @return void
      */
     public function initializeObject($obj)
     {
@@ -2880,6 +2887,6 @@ public function initializeObject($obj)
 
     private function objToStr($obj)
     {
-        return method_exists($obj, '__toString') ? (string)$obj : get_class($obj) . '@' . spl_object_hash($obj);
+        return method_exists($obj, '__toString') ? (string) $obj : get_class($obj) . '@' . spl_object_hash($obj);
     }
 }
diff --git a/lib/Doctrine/ODM/MongoDB/Utility/CollectionHelper.php b/lib/Doctrine/ODM/MongoDB/Utility/CollectionHelper.php
index fa4de7cdce..87e7fd4730 100644
--- a/lib/Doctrine/ODM/MongoDB/Utility/CollectionHelper.php
+++ b/lib/Doctrine/ODM/MongoDB/Utility/CollectionHelper.php
@@ -1,17 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Utility;
+
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use function in_array;
 
 /**
  * Utility class used to unify checks on how collection strategies should behave.
  *
- * @since   1.0
  * @internal
  */
 class CollectionHelper
 {
-    const DEFAULT_STRATEGY = ClassMetadata::STORAGE_STRATEGY_PUSH_ALL;
+    public const DEFAULT_STRATEGY = ClassMetadata::STORAGE_STRATEGY_PUSH_ALL;
 
     /**
      * Returns whether update query must be included in query updating owning document.
@@ -60,7 +63,7 @@ public static function usesSet($strategy)
                 ClassMetadata::STORAGE_STRATEGY_SET,
                 ClassMetadata::STORAGE_STRATEGY_SET_ARRAY,
                 ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET,
-                ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY
+                ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY,
             ]
         );
     }
diff --git a/lib/Doctrine/ODM/MongoDB/Utility/LifecycleEventManager.php b/lib/Doctrine/ODM/MongoDB/Utility/LifecycleEventManager.php
index a79b80191f..d50b2597a0 100644
--- a/lib/Doctrine/ODM/MongoDB/Utility/LifecycleEventManager.php
+++ b/lib/Doctrine/ODM/MongoDB/Utility/LifecycleEventManager.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Utility;
 
 use Doctrine\Common\EventManager;
@@ -12,10 +14,10 @@
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\UnitOfWork;
+use function get_class;
 
 /**
  * @internal
- * @since 1.1
  */
 class LifecycleEventManager
 {
@@ -23,7 +25,7 @@ class LifecycleEventManager
      * @var DocumentManager
      */
     private $dm;
-    
+
     /**
      * @var EventManager
      */
@@ -34,11 +36,6 @@ class LifecycleEventManager
      */
     private $uow;
 
-    /**
-     * @param DocumentManager $dm
-     * @param UnitOfWork $uow
-     * @param EventManager $evm
-     */
     public function __construct(DocumentManager $dm, UnitOfWork $uow, EventManager $evm)
     {
         $this->dm = $dm;
@@ -48,7 +45,7 @@ public function __construct(DocumentManager $dm, UnitOfWork $uow, EventManager $
 
     /**
      * @param object $proxy
-     * @param mixed $id
+     * @param mixed  $id
      * @return bool Returns whether the exceptionDisabled flag was set
      */
     public function documentNotFound($proxy, $id)
@@ -62,7 +59,6 @@ public function documentNotFound($proxy, $id)
     /**
      * Dispatches postCollectionLoad event.
      *
-     * @param PersistentCollectionInterface $coll
      */
     public function postCollectionLoad(PersistentCollectionInterface $coll)
     {
@@ -73,12 +69,11 @@ public function postCollectionLoad(PersistentCollectionInterface $coll)
     /**
      * Invokes postPersist callbacks and events for given document cascading them to embedded documents as well.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function postPersist(ClassMetadata $class, $document)
     {
-        $class->invokeLifecycleCallbacks(Events::postPersist, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        $class->invokeLifecycleCallbacks(Events::postPersist, $document, [new LifecycleEventArgs($document, $this->dm)]);
         $this->evm->dispatchEvent(Events::postPersist, new LifecycleEventArgs($document, $this->dm));
         $this->cascadePostPersist($class, $document);
     }
@@ -86,12 +81,11 @@ public function postPersist(ClassMetadata $class, $document)
     /**
      * Invokes postRemove callbacks and events for given document.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function postRemove(ClassMetadata $class, $document)
     {
-        $class->invokeLifecycleCallbacks(Events::postRemove, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        $class->invokeLifecycleCallbacks(Events::postRemove, $document, [new LifecycleEventArgs($document, $this->dm)]);
         $this->evm->dispatchEvent(Events::postRemove, new LifecycleEventArgs($document, $this->dm));
     }
 
@@ -99,12 +93,11 @@ public function postRemove(ClassMetadata $class, $document)
      * Invokes postUpdate callbacks and events for given document. The same will be done for embedded documents owned
      * by given document unless they were new in which case postPersist callbacks and events will be dispatched.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function postUpdate(ClassMetadata $class, $document)
     {
-        $class->invokeLifecycleCallbacks(Events::postUpdate, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        $class->invokeLifecycleCallbacks(Events::postUpdate, $document, [new LifecycleEventArgs($document, $this->dm)]);
         $this->evm->dispatchEvent(Events::postUpdate, new LifecycleEventArgs($document, $this->dm));
         $this->cascadePostUpdate($class, $document);
     }
@@ -112,39 +105,34 @@ public function postUpdate(ClassMetadata $class, $document)
     /**
      * Invokes prePersist callbacks and events for given document.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function prePersist(ClassMetadata $class, $document)
     {
-        $class->invokeLifecycleCallbacks(Events::prePersist, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        $class->invokeLifecycleCallbacks(Events::prePersist, $document, [new LifecycleEventArgs($document, $this->dm)]);
         $this->evm->dispatchEvent(Events::prePersist, new LifecycleEventArgs($document, $this->dm));
     }
 
     /**
      * Invokes prePersist callbacks and events for given document.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function preRemove(ClassMetadata $class, $document)
     {
-        $class->invokeLifecycleCallbacks(Events::preRemove, $document, array(new LifecycleEventArgs($document, $this->dm)));
+        $class->invokeLifecycleCallbacks(Events::preRemove, $document, [new LifecycleEventArgs($document, $this->dm)]);
         $this->evm->dispatchEvent(Events::preRemove, new LifecycleEventArgs($document, $this->dm));
     }
 
     /**
      * Invokes preUpdate callbacks and events for given document cascading them to embedded documents as well.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     public function preUpdate(ClassMetadata $class, $document)
     {
-        if ( ! empty($class->lifecycleCallbacks[Events::preUpdate])) {
-            $class->invokeLifecycleCallbacks(Events::preUpdate, $document, array(
-                new PreUpdateEventArgs($document, $this->dm, $this->uow->getDocumentChangeSet($document))
-            ));
+        if (! empty($class->lifecycleCallbacks[Events::preUpdate])) {
+            $class->invokeLifecycleCallbacks(Events::preUpdate, $document, [new PreUpdateEventArgs($document, $this->dm, $this->uow->getDocumentChangeSet($document))]);
             $this->uow->recomputeSingleDocumentChangeSet($class, $document);
         }
         $this->evm->dispatchEvent(Events::preUpdate, new PreUpdateEventArgs($document, $this->dm, $this->uow->getDocumentChangeSet($document)));
@@ -154,7 +142,6 @@ public function preUpdate(ClassMetadata $class, $document)
     /**
      * Cascades the preUpdate event to embedded documents.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     private function cascadePreUpdate(ClassMetadata $class, $document)
@@ -164,7 +151,7 @@ private function cascadePreUpdate(ClassMetadata $class, $document)
             if ($value === null) {
                 continue;
             }
-            $values = $mapping['type'] === ClassMetadata::ONE ? array($value) : $value;
+            $values = $mapping['type'] === ClassMetadata::ONE ? [$value] : $value;
 
             foreach ($values as $entry) {
                 if ($this->uow->isScheduledForInsert($entry) || empty($this->uow->getDocumentChangeSet($entry))) {
@@ -178,7 +165,6 @@ private function cascadePreUpdate(ClassMetadata $class, $document)
     /**
      * Cascades the postUpdate and postPersist events to embedded documents.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     private function cascadePostUpdate(ClassMetadata $class, $document)
@@ -188,7 +174,7 @@ private function cascadePostUpdate(ClassMetadata $class, $document)
             if ($value === null) {
                 continue;
             }
-            $values = $mapping['type'] === ClassMetadata::ONE ? array($value) : $value;
+            $values = $mapping['type'] === ClassMetadata::ONE ? [$value] : $value;
 
             foreach ($values as $entry) {
                 if (empty($this->uow->getDocumentChangeSet($entry)) && ! $this->uow->hasScheduledCollections($entry)) {
@@ -196,7 +182,7 @@ private function cascadePostUpdate(ClassMetadata $class, $document)
                 }
                 $entryClass = $this->dm->getClassMetadata(get_class($entry));
                 $event = $this->uow->isScheduledForInsert($entry) ? Events::postPersist : Events::postUpdate;
-                $entryClass->invokeLifecycleCallbacks($event, $entry, array(new LifecycleEventArgs($entry, $this->dm)));
+                $entryClass->invokeLifecycleCallbacks($event, $entry, [new LifecycleEventArgs($entry, $this->dm)]);
                 $this->evm->dispatchEvent($event, new LifecycleEventArgs($entry, $this->dm));
 
                 $this->cascadePostUpdate($entryClass, $entry);
@@ -207,7 +193,6 @@ private function cascadePostUpdate(ClassMetadata $class, $document)
     /**
      * Cascades the postPersist events to embedded documents.
      *
-     * @param ClassMetadata $class
      * @param object $document
      */
     private function cascadePostPersist(ClassMetadata $class, $document)
@@ -217,7 +202,7 @@ private function cascadePostPersist(ClassMetadata $class, $document)
             if ($value === null) {
                 continue;
             }
-            $values = $mapping['type'] === ClassMetadata::ONE ? array($value) : $value;
+            $values = $mapping['type'] === ClassMetadata::ONE ? [$value] : $value;
             foreach ($values as $embeddedDocument) {
                 $this->postPersist($this->dm->getClassMetadata(get_class($embeddedDocument)), $embeddedDocument);
             }
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
new file mode 100644
index 0000000000..3b6f7c2d61
--- /dev/null
+++ b/phpcs.xml.dist
@@ -0,0 +1,80 @@
+<?xml version="1.0"?>
+<ruleset>
+    <arg name="basepath" value="."/>
+    <arg name="extensions" value="php"/>
+    <arg name="parallel" value="80"/>
+    <arg name="cache" value=".phpcs-cache"/>
+    <arg name="colors" />
+
+    <!-- Ignore warnings and show progress of the run -->
+    <arg value="np"/>
+
+    <file>lib</file>
+    <file>tests</file>
+    <file>tools</file>
+
+    <exclude-pattern>tests/Proxies*</exclude-pattern>
+    <exclude-pattern>tests/Hydrators*</exclude-pattern>
+    <exclude-pattern>tests/PersistentCollections*</exclude-pattern>
+
+    <rule ref="Doctrine">
+        <!-- Traversable type hints often end up as mixed[], so we skip them for now -->
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingTraversablePropertyTypeHintSpecification" />
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingTraversableParameterTypeHintSpecification" />
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingTraversableReturnTypeHintSpecification" />
+
+        <!-- Will cause BC breaks to method signatures - disabled for now -->
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingParameterTypeHint" />
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingReturnTypeHint" />
+
+        <exclude name="Generic.Formatting.MultipleStatementAlignment" />
+
+        <!-- Disabled due to the large number of false positives in 4.4.4 -->
+        <exclude name="SlevomatCodingStandard.Namespaces.UnusedUses.MismatchingCaseSensitivity" />
+
+        <!-- Disabled to avoid class renaming - to be handled in a separate PR -->
+        <exclude name="SlevomatCodingStandard.Classes.SuperfluousAbstractClassNaming" />
+        <exclude name="SlevomatCodingStandard.Classes.SuperfluousExceptionNaming" />
+        <exclude name="SlevomatCodingStandard.Classes.SuperfluousInterfaceNaming" />
+
+        <!-- The following rules are intended to be enabled one-by-one to have reviewable diffs -->
+
+        <exclude name="Generic.CodeAnalysis.EmptyStatement.DetectedFOREACH" />
+        <exclude name="Generic.CodeAnalysis.EmptyStatement.DetectedIF" />
+        <exclude name="Generic.NamingConventions.UpperCaseConstantName.ConstantNotUpperCase" />
+        <exclude name="Generic.PHP.ForbiddenFunctions.Found" />
+        <exclude name="Generic.PHP.ForbiddenFunctions.FoundWithAlternative" />
+        <exclude name="PSR1.Classes.ClassDeclaration.MissingNamespace" />
+        <exclude name="PSR1.Methods.CamelCapsMethodName.NotCamelCaps" />
+        <exclude name="PSR2.ControlStructures.SwitchDeclaration.WrongOpenercase" />
+        <exclude name="SlevomatCodingStandard.Commenting.RequireOneLinePropertyDocComment" />
+        <exclude name="SlevomatCodingStandard.ControlStructures.AssignmentInCondition.AssignmentInCondition" />
+        <exclude name="SlevomatCodingStandard.ControlStructures.EarlyExit" />
+        <exclude name="SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedMethod" />
+        <exclude name="SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedProperty" />
+        <exclude name="SlevomatCodingStandard.Classes.UnusedPrivateElements.WriteOnlyProperty" />
+        <exclude name="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.MissingPropertyTypeHint" />
+        <exclude name="Squiz.Classes.ValidClassName.NotCamelCaps" />
+        <exclude name="Squiz.Commenting.FunctionComment.ThrowsNotCapital" />
+        <exclude name="Squiz.Commenting.FunctionComment.ThrowsNoFullStop" />
+        <exclude name="Squiz.Commenting.FunctionComment.WrongStyle" />
+        <exclude name="Squiz.Classes.ClassFileName.NoMatch" />
+        <exclude name="Squiz.Scope.MethodScope.Missing" />
+        <exclude name="Squiz.Strings.DoubleQuoteUsage.ContainsVar" />
+    </rule>
+
+    <!-- Require no space around colon in return types -->
+    <rule ref="SlevomatCodingStandard.TypeHints.ReturnTypeHintSpacing">
+        <properties>
+            <property name="spacesCountBeforeColon" value="0"/>
+        </properties>
+    </rule>
+
+    <rule ref="Generic.NamingConventions.UpperCaseConstantName.ClassConstantNotUpperCase">
+        <exclude-pattern>lib/Doctrine/ODM/MongoDB/Events.php</exclude-pattern>
+    </rule>
+
+    <rule ref="PSR1.Classes.ClassDeclaration.MultipleClasses">
+        <exclude-pattern>*/tests/*</exclude-pattern>
+    </rule>
+</ruleset>
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationOperatorsProviderTrait.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationOperatorsProviderTrait.php
index e0c56d1714..7b8f30d86f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationOperatorsProviderTrait.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationOperatorsProviderTrait.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation;
 
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Documents\User;
+use function is_array;
 
 trait AggregationOperatorsProviderTrait
 {
@@ -149,7 +152,7 @@ public static function provideExpressionOperators()
                     return [
                         $expr->gte('$field', 5),
                         '$field',
-                        '$otherField'
+                        '$otherField',
                     ];
                 },
             ],
@@ -308,10 +311,10 @@ public static function provideExpressionOperators()
                     '$let' => [
                         'vars' => [
                             'total' => ['$add' => ['$price', '$tax']],
-                            'discounted' => ['$cond' => ['if' => '$applyDiscount', 'then' => 0.9, 'else' => 1]]
+                            'discounted' => ['$cond' => ['if' => '$applyDiscount', 'then' => 0.9, 'else' => 1]],
                         ],
-                        'in' => ['$multiply' => ['$$total', '$$discounted']]
-                    ]
+                        'in' => ['$multiply' => ['$$total', '$$discounted']],
+                    ],
                 ],
                 'operator' => 'let',
                 'args' => function (Expr $expr) {
@@ -363,7 +366,7 @@ public static function provideExpressionOperators()
                     return [
                         '$quizzes',
                         'grade',
-                        $expr->add('$$grade', 2)
+                        $expr->add('$$grade', 2),
                     ];
                 },
             ],
@@ -440,7 +443,7 @@ public static function provideExpressionOperators()
                         ['sum' => 0, 'product' => 1],
                         $expr
                             ->add('$$value.sum', '$$this')
-                            ->multiply('$$value.product', '$$this')
+                            ->multiply('$$value.product', '$$this'),
                     ];
                 },
             ],
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationTestTrait.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationTestTrait.php
index 694a6e8276..1661e16d91 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationTestTrait.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/AggregationTestTrait.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -24,7 +26,7 @@ protected function getTestAggregationBuilder(string $documentName = User::class)
     }
 
     /**
-     * @return \PHPUnit_Framework_MockObject_MockObject|\Doctrine\ODM\MongoDB\Aggregation\Expr
+     * @return \PHPUnit_Framework_MockObject_MockObject|AggregationExpr
      */
     protected function getMockAggregationExpr()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/BuilderTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/BuilderTest.php
index e3fa5d414c..f9305f54a4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/BuilderTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/BuilderTest.php
@@ -1,10 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation;
 
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
-
-class BuilderTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Article;
+use Documents\BlogPost;
+use Documents\BlogTagAggregation;
+use Documents\CmsComment;
+use Documents\GuestServer;
+use Documents\Tag;
+use MongoDB\BSON\UTCDateTime;
+
+class BuilderTest extends BaseTest
 {
     public function testGetPipeline()
     {
@@ -20,39 +30,43 @@ public function testGetPipeline()
                         'hasCoordinates' => ['$exists' => true],
                         'username' => 'foo',
                     ],
-                    'num' => 10
-                ]
+                    'num' => 10,
+                ],
             ],
-            ['$match' =>
+            [
+            '$match' =>
                 [
                     '$or' => [
                         ['username' => 'admin'],
-                        ['username' => 'administrator']
+                        ['username' => 'administrator'],
                     ],
-                    'group' => ['$in' => ['a', 'b']]
-                ]
+                    'group' => ['$in' => ['a', 'b']],
+                ],
             ],
             ['$sample' => ['size' => 10]],
-            ['$lookup' =>
+            [
+            '$lookup' =>
                 [
                     'from' => 'orders',
                     'localField' => '_id',
                     'foreignField' => 'user.$id',
-                    'as' => 'orders'
-                ]
+                    'as' => 'orders',
+                ],
             ],
             ['$unwind' => 'a'],
             ['$unwind' => 'b'],
-            ['$redact' =>
+            [
+            '$redact' =>
                 [
                     '$cond' => [
                         'if' => ['$lte' => ['$accessLevel', 3]],
                         'then' => '$$KEEP',
                         'else' => '$$REDACT',
-                    ]
-                ]
+                    ],
+                ],
             ],
-            ['$project' =>
+            [
+            '$project' =>
                 [
                     '_id' => false,
                     'user' => true,
@@ -63,33 +77,34 @@ public function testGetPipeline()
                             'if' => [
                                 '$and' => [
                                     ['$eq' => ['$useAlternateDeliveryAddress', true]],
-                                    ['$ne' => ['$deliveryAddress', null]]
-                                ]
+                                    ['$ne' => ['$deliveryAddress', null]],
+                                ],
                             ],
                             'then' => '$deliveryAddress',
-                            'else' => '$invoiceAddress'
-                        ]
-                    ]
-                ]
+                            'else' => '$invoiceAddress',
+                        ],
+                    ],
+                ],
             ],
-            ['$group' =>
+            [
+            '$group' =>
                 [
                     '_id' => '$user',
                     'numOrders' => ['$sum' => 1],
                     'amount' => [
                         'total' => ['$sum' => '$amount'],
-                        'avg' => ['$avg' => '$amount']
-                    ]
-                ]
+                        'avg' => ['$avg' => '$amount'],
+                    ],
+                ],
             ],
             ['$sort' => ['totalAmount' => 0]],
             ['$sort' => ['numOrders' => -1, 'avgAmount' => 1]],
             ['$limit' => 5],
             ['$skip' => 2],
-            ['$out' => 'collectionName']
+            ['$out' => 'collectionName'],
         ];
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\BlogPost::class);
+        $builder = $this->dm->createAggregationBuilder(BlogPost::class);
         $builder
             ->geoNear($point)
                 ->distanceField('distance')
@@ -153,10 +168,10 @@ public function testAggregationBuilder()
     {
         $this->insertTestData();
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\BlogPost::class);
+        $builder = $this->dm->createAggregationBuilder(BlogPost::class);
 
         $resultCursor = $builder
-            ->hydrate(\Documents\BlogTagAggregation::class)
+            ->hydrate(BlogTagAggregation::class)
             ->unwind('$tags')
             ->group()
                 ->field('id')
@@ -170,7 +185,7 @@ public function testAggregationBuilder()
 
         $results = $resultCursor->toArray();
         $this->assertCount(2, $results);
-        $this->assertInstanceOf(\Documents\BlogTagAggregation::class, $results[0]);
+        $this->assertInstanceOf(BlogTagAggregation::class, $results[0]);
 
         $this->assertSame('baseball', $results[0]->tag->name);
         $this->assertSame(3, $results[0]->numPosts);
@@ -178,7 +193,7 @@ public function testAggregationBuilder()
 
     public function testPipelineConvertsTypes()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\Article::class);
+        $builder = $this->dm->createAggregationBuilder(Article::class);
         $dateTime = new \DateTimeImmutable('2000-01-01T00:00Z');
         $builder
             ->group()
@@ -202,19 +217,19 @@ public function testPipelineConvertsTypes()
                 '$group' => [
                     '_id' => [
                         '$cond' => [
-                            'if' => ['$lt' => ['$createdAt', new \MongoDB\BSON\UTCDateTime((int) $dateTime->format('Uv'))]],
+                            'if' => ['$lt' => ['$createdAt', new UTCDateTime((int) $dateTime->format('Uv'))]],
                             'then' => true,
                             'else' => false,
-                        ]
+                        ],
                     ],
                     'numPosts' => ['$sum' => 1],
-                ]
+                ],
             ],
             [
                 '$replaceRoot' => [
-                    'isToday' => ['$eq' => ['$createdAt', new \MongoDB\BSON\UTCDateTime((int) $dateTime->format('Uv'))]],
-                ]
-            ]
+                    'isToday' => ['$eq' => ['$createdAt', new UTCDateTime((int) $dateTime->format('Uv'))]],
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -222,7 +237,7 @@ public function testPipelineConvertsTypes()
 
     public function testFieldNameConversion()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\CmsComment::class);
+        $builder = $this->dm->createAggregationBuilder(CmsComment::class);
         $builder
             ->match()
                 ->field('authorIp')
@@ -240,15 +255,11 @@ public function testFieldNameConversion()
             [
                 '$project' => ['ip' => true],
             ],
-            [
-                '$unwind' => 'ip',
-            ],
+            ['$unwind' => 'ip'],
             [
                 '$sort' => ['ip' => 1],
             ],
-            [
-                '$replaceRoot' => '$ip',
-            ]
+            ['$replaceRoot' => '$ip'],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -258,11 +269,11 @@ public function testBuilderAppliesFilterAndDiscriminatorWithMatchStage()
     {
         $this->dm->getFilterCollection()->enable('testFilter');
         $filter = $this->dm->getFilterCollection()->getFilter('testFilter');
-        $filter->setParameter('class', \Documents\GuestServer::class);
+        $filter->setParameter('class', GuestServer::class);
         $filter->setParameter('field', 'filtered');
         $filter->setParameter('value', true);
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\GuestServer::class);
+        $builder = $this->dm->createAggregationBuilder(GuestServer::class);
         $builder
             ->project()
             ->excludeFields(['_id']);
@@ -279,7 +290,7 @@ public function testBuilderAppliesFilterAndDiscriminatorWithMatchStage()
             ],
             [
                 '$project' => ['_id' => false],
-            ]
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -289,11 +300,11 @@ public function testBuilderAppliesFilterAndDiscriminatorWithGeoNearStage()
     {
         $this->dm->getFilterCollection()->enable('testFilter');
         $filter = $this->dm->getFilterCollection()->getFilter('testFilter');
-        $filter->setParameter('class', \Documents\GuestServer::class);
+        $filter->setParameter('class', GuestServer::class);
         $filter->setParameter('field', 'filtered');
         $filter->setParameter('value', true);
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\GuestServer::class);
+        $builder = $this->dm->createAggregationBuilder(GuestServer::class);
         $builder
             ->geoNear(0, 0);
 
@@ -320,7 +331,7 @@ public function testBuilderWithOutStageReturnsNoData()
     {
         $this->insertTestData();
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\BlogPost::class);
+        $builder = $this->dm->createAggregationBuilder(BlogPost::class);
         $builder
             ->out('sampleCollection');
 
@@ -330,25 +341,25 @@ public function testBuilderWithOutStageReturnsNoData()
 
     private function insertTestData()
     {
-        $baseballTag = new \Documents\Tag('baseball');
-        $footballTag = new \Documents\Tag('football');
+        $baseballTag = new Tag('baseball');
+        $footballTag = new Tag('football');
 
-        $blogPost = new \Documents\BlogPost();
+        $blogPost = new BlogPost();
         $blogPost->name = 'Test 1';
         $blogPost->addTag($baseballTag);
         $this->dm->persist($blogPost);
 
-        $blogPost = new \Documents\BlogPost();
+        $blogPost = new BlogPost();
         $blogPost->name = 'Test 2';
         $blogPost->addTag($baseballTag);
         $this->dm->persist($blogPost);
 
-        $blogPost = new \Documents\BlogPost();
+        $blogPost = new BlogPost();
         $blogPost->name = 'Test 3';
         $blogPost->addTag($footballTag);
         $this->dm->persist($blogPost);
 
-        $blogPost = new \Documents\BlogPost();
+        $blogPost = new BlogPost();
         $blogPost->name = 'Test 4';
         $blogPost->addTag($baseballTag);
         $blogPost->addTag($footballTag);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/ExprTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/ExprTest.php
index 5b7fae2c9d..58116c720d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/ExprTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/ExprTest.php
@@ -1,11 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation;
 
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
-use Documents\User;
 
 class ExprTest extends BaseTest
 {
@@ -60,8 +60,8 @@ public function testExpression()
             [
                 'nested' => [
                     'dayOfMonth' => ['$dayOfMonth' => '$dateField'],
-                    'dayOfWeek' => ['$dayOfWeek' => '$dateField']
-                ]
+                    'dayOfWeek' => ['$dayOfWeek' => '$dateField'],
+                ],
             ],
             $expr->getExpression()
         );
@@ -103,7 +103,7 @@ public function testSwitch()
                         ['case' => ['$eq' => ['$numElements', 1]], 'then' => 'One element given'],
                     ],
                     'default' => ['$concat' => ['$numElements', ' elements given']],
-                ]
+                ],
             ],
             $expr->getExpression()
         );
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/AddFieldsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/AddFieldsTest.php
index 7fbfe5e78b..18020e126c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/AddFieldsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/AddFieldsTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\AddFields;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketAutoTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketAutoTest.php
index df4ed013f5..e85aa87399 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketAutoTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketAutoTest.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\BucketAuto;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationTestTrait;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsComment;
 use Documents\User;
 
-class BucketTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class BucketTest extends BaseTest
 {
     use AggregationTestTrait;
 
@@ -23,12 +26,14 @@ public function testBucketAutoStage()
             ->field('averageValue')
             ->avg('$value');
 
-        $this->assertSame(['$bucketAuto' => [
+        $this->assertSame([
+        '$bucketAuto' => [
             'groupBy' => '$someField',
             'buckets' => 3,
             'granularity' => 'R10',
-            'output' => ['averageValue' => ['$avg' => '$value']]
-        ]], $bucketStage->getExpression());
+            'output' => ['averageValue' => ['$avg' => '$value']],
+        ],
+        ], $bucketStage->getExpression());
     }
 
     public function testBucketAutoFromBuilder()
@@ -42,12 +47,15 @@ public function testBucketAutoFromBuilder()
             ->field('averageValue')
             ->avg('$value');
 
-        $this->assertSame([['$bucketAuto' => [
+        $this->assertSame([[
+        '$bucketAuto' => [
             'groupBy' => '$someField',
             'buckets' => 3,
             'granularity' => 'R10',
-            'output' => ['averageValue' => ['$avg' => '$value']]
-        ]]], $builder->getPipeline());
+            'output' => ['averageValue' => ['$avg' => '$value']],
+        ],
+        ],
+        ], $builder->getPipeline());
     }
 
     public function testBucketAutoSkipsUndefinedProperties()
@@ -57,10 +65,12 @@ public function testBucketAutoSkipsUndefinedProperties()
             ->groupBy('$someField')
             ->buckets(3);
 
-        $this->assertSame(['$bucketAuto' => [
+        $this->assertSame([
+        '$bucketAuto' => [
             'groupBy' => '$someField',
             'buckets' => 3,
-        ]], $bucketStage->getExpression());
+        ],
+        ], $bucketStage->getExpression());
     }
 
     public function testFieldNameConversion()
@@ -76,12 +86,15 @@ public function testFieldNameConversion()
                 ->avg('$value');
 
         $this->assertEquals(
-            [['$bucketAuto' => [
+            [[
+            '$bucketAuto' => [
                 'groupBy' => '$ip',
                 'buckets' => 3,
                 'granularity' => 'R10',
-                'output' => ['averageValue' => ['$avg' => '$value']]
-            ]]],
+                'output' => ['averageValue' => ['$avg' => '$value']],
+            ],
+            ],
+            ],
             $builder->getPipeline()
         );
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketTest.php
index 735e72f326..5ad9f43871 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketTest.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Bucket;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationTestTrait;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsComment;
 use Documents\User;
 
-class BucketAutoTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class BucketAutoTest extends BaseTest
 {
     use AggregationTestTrait;
 
@@ -23,12 +26,14 @@ public function testBucketStage()
             ->field('averageValue')
             ->avg('$value');
 
-        $this->assertSame(['$bucket' => [
+        $this->assertSame([
+        '$bucket' => [
             'groupBy' => '$someField',
             'boundaries' => [1, 2, 3],
             'default' => 0,
-            'output' => ['averageValue' => ['$avg' => '$value']]
-        ]], $bucketStage->getExpression());
+            'output' => ['averageValue' => ['$avg' => '$value']],
+        ],
+        ], $bucketStage->getExpression());
     }
 
     public function testBucketFromBuilder()
@@ -42,12 +47,15 @@ public function testBucketFromBuilder()
             ->field('averageValue')
             ->avg('$value');
 
-        $this->assertSame([['$bucket' => [
+        $this->assertSame([[
+        '$bucket' => [
             'groupBy' => '$someField',
             'boundaries' => [1, 2, 3],
             'default' => 0,
-            'output' => ['averageValue' => ['$avg' => '$value']]
-        ]]], $builder->getPipeline());
+            'output' => ['averageValue' => ['$avg' => '$value']],
+        ],
+        ],
+        ], $builder->getPipeline());
     }
 
     public function testBucketSkipsUndefinedProperties()
@@ -57,10 +65,12 @@ public function testBucketSkipsUndefinedProperties()
             ->groupBy('$someField')
             ->boundaries(1, 2, 3);
 
-        $this->assertSame(['$bucket' => [
+        $this->assertSame([
+        '$bucket' => [
             'groupBy' => '$someField',
             'boundaries' => [1, 2, 3],
-        ]], $bucketStage->getExpression());
+        ],
+        ], $bucketStage->getExpression());
     }
 
     public function testFieldNameConversion()
@@ -76,12 +86,15 @@ public function testFieldNameConversion()
                 ->avg('$value');
 
         $this->assertEquals(
-            [['$bucket' => [
+            [[
+            '$bucket' => [
                 'groupBy' => '$ip',
                 'boundaries' => [1, 2, 3],
                 'default' => 0,
-                'output' => ['averageValue' => ['$avg' => '$value']]
-            ]]],
+                'output' => ['averageValue' => ['$avg' => '$value']],
+            ],
+            ],
+            ],
             $builder->getPipeline()
         );
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CollStatsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CollStatsTest.php
index e16ea30d92..8f93b8c096 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CollStatsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CollStatsTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\CollStats;
@@ -51,8 +53,9 @@ public function testCollStatsFromBuilder()
         $this->assertSame([[
             '$collStats' => [
                 'latencyStats' => ['histograms' => true],
-                'storageStats' => []
-            ]
-        ]], $builder->getPipeline());
+                'storageStats' => [],
+            ],
+        ],
+        ], $builder->getPipeline());
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CountTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CountTest.php
index 246a88134f..175628f2fb 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CountTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/CountTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Count;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/FacetTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/FacetTest.php
index 55302939e4..a8350c27ed 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/FacetTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/FacetTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Facet;
@@ -26,7 +28,7 @@ public function testFacetStage()
             '$facet' => [
                 'someField' => [['$sortByCount' => '$tags']],
                 'otherField' => [['$sortByCount' => '$comments']],
-            ]
+            ],
         ], $facetStage->getExpression());
     }
 
@@ -46,8 +48,9 @@ public function testFacetFromBuilder()
             '$facet' => [
                 'someField' => [['$sortByCount' => '$tags']],
                 'otherField' => [['$sortByCount' => '$comments']],
-            ]
-        ]], $builder->getPipeline());
+            ],
+        ],
+        ], $builder->getPipeline());
     }
 
     public function testFacetThrowsExceptionWithoutFieldName()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GeoNearTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GeoNearTest.php
index 716a80380b..bfc634d75a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GeoNearTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GeoNearTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\GeoNear;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GraphLookupTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GraphLookupTest.php
index a9f11c7b90..dedc6c5d44 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GraphLookupTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GraphLookupTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Builder;
@@ -7,14 +9,17 @@
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
 use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationTestTrait;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\GraphLookup\Airport;
 use Documents\GraphLookup\Employee;
 use Documents\GraphLookup\ReportingHierarchy;
 use Documents\GraphLookup\Traveller;
 use Documents\Sharded\ShardedOne;
 use Documents\User;
+use function array_merge;
+use function count;
 
-class GraphLookupTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GraphLookupTest extends BaseTest
 {
     use AggregationTestTrait;
 
@@ -34,14 +39,16 @@ public function testGraphLookupStage()
             ->alias('reportingHierarchy');
 
         $this->assertEquals(
-            ['$graphLookup' => [
+            [
+            '$graphLookup' => [
                 'from' => 'employees',
                 'startWith' => '$reportsTo',
                 'connectFromField' => 'reportsTo',
                 'connectToField' => 'name',
                 'as' => 'reportingHierarchy',
                 'restrictSearchWithMatch' => (object) [],
-            ]],
+            ],
+            ],
             $graphLookupStage->getExpression()
         );
     }
@@ -56,14 +63,17 @@ public function testGraphLookupFromBuilder()
             ->alias('reportingHierarchy');
 
         $this->assertEquals(
-            [['$graphLookup' => [
+            [[
+            '$graphLookup' => [
                 'from' => 'employees',
                 'startWith' => '$reportsTo',
                 'connectFromField' => 'reportsTo',
                 'connectToField' => 'name',
                 'as' => 'reportingHierarchy',
                 'restrictSearchWithMatch' => (object) [],
-            ]]],
+            ],
+            ],
+            ],
             $builder->getPipeline()
         );
     }
@@ -83,7 +93,8 @@ public function testGraphLookupWithMatch()
             ->depthField('depth');
 
         $this->assertSame(
-            [['$graphLookup' => [
+            [[
+            '$graphLookup' => [
                 'from' => 'employees',
                 'startWith' => '$reportsTo',
                 'connectFromField' => 'reportsTo',
@@ -92,7 +103,9 @@ public function testGraphLookupWithMatch()
                 'restrictSearchWithMatch' => ['hobbies' => 'golf'],
                 'maxDepth' => 1,
                 'depthField' => 'depth',
-            ]]],
+            ],
+            ],
+            ],
             $builder->getPipeline()
         );
     }
@@ -109,7 +122,7 @@ public function provideEmployeeAggregations()
                     'startWith' => '$reportsTo.id',
                     'connectFromField' => 'reportsTo.id',
                     'connectToField' => '_id',
-                ]
+                ],
             ],
             'owningSideId' => [
                 'addGraphLookupStage' => function (Builder $builder) {
@@ -120,7 +133,7 @@ public function provideEmployeeAggregations()
                     'startWith' => '$reportsToId',
                     'connectFromField' => 'reportsToId',
                     'connectToField' => '_id',
-                ]
+                ],
             ],
             'inverseSide' => [
                 'addGraphLookupStage' => function (Builder $builder) {
@@ -131,7 +144,7 @@ public function provideEmployeeAggregations()
                     'startWith' => '$reportsTo.id',
                     'connectFromField' => 'reportsTo.id',
                     'connectToField' => '_id',
-                ]
+                ],
             ],
         ];
     }
@@ -153,8 +166,8 @@ public function testGraphLookupWithEmployees(\Closure $addGraphLookupStage, arra
                     'from' => 'Employee',
                     'as' => 'reportingHierarchy',
                     'restrictSearchWithMatch' => (object) [],
-                ], $expectedFields)
-            ]
+                ], $expectedFields),
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -187,7 +200,7 @@ public function provideTravellerAggregations()
                     'startWith' => '$nearestAirport.id',
                     'connectFromField' => 'connections.id',
                     'connectToField' => '_id',
-                ]
+                ],
             ],
             'owningSideId' => [
                 'addGraphLookupStage' => function (Builder $builder) {
@@ -201,7 +214,7 @@ public function provideTravellerAggregations()
                     'startWith' => '$nearestAirportId',
                     'connectFromField' => 'connectionIds',
                     'connectToField' => '_id',
-                ]
+                ],
             ],
         ];
     }
@@ -224,8 +237,8 @@ public function testGraphLookupWithTraveller(\Closure $addGraphLookupStage, arra
                     'maxDepth' => 2,
                     'depthField' => 'numConnections',
                     'restrictSearchWithMatch' => (object) [],
-                ], $expectedFields)
-            ]
+                ], $expectedFields),
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -265,8 +278,8 @@ public function testGraphLookupWithUnmappedFields()
                     'connectToField' => 'target',
                     'as' => 'targets',
                     'restrictSearchWithMatch' => (object) [],
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GroupTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GroupTest.php
index 9c91936921..894d6798c1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GroupTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/GroupTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
@@ -41,7 +43,9 @@ public function provideProxiedExprMethods()
         return [
             'addToSet()' => ['addToSet', ['$field']],
             'avg()' => ['avg', ['$field']],
-            'expression()' => ['expression', function (Expr $expr) {
+            'expression()' => [
+        'expression',
+        function (Expr $expr) {
                 $expr
                     ->field('dayOfMonth')
                     ->dayOfMonth('$dateField')
@@ -49,7 +53,8 @@ public function provideProxiedExprMethods()
                     ->dayOfWeek('$dateField');
 
                 return [$expr];
-            }],
+        },
+            ],
             'first()' => ['first', ['$field']],
             'last()' => ['last', ['$field']],
             'max()' => ['max', ['$field']],
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/IndexStatsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/IndexStatsTest.php
index 1a6d0fafad..4b1857c69d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/IndexStatsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/IndexStatsTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\IndexStats;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LimitTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LimitTest.php
index 091ddac779..578fabe73e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LimitTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LimitTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Limit;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LookupTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LookupTest.php
index de593bce57..9878adb29c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LookupTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/LookupTest.php
@@ -1,12 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsComment;
+use Documents\ReferenceUser;
 use Documents\Sharded\ShardedOne;
+use Documents\SimpleReferenceUser;
+use Documents\User;
 
-class LookupTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class LookupTest extends BaseTest
 {
     public function setUp()
     {
@@ -17,7 +23,7 @@ public function setUp()
 
     public function testLookupStage()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->lookup('user')
                 ->alias('user');
@@ -29,8 +35,8 @@ public function testLookupStage()
                     'localField' => 'userId',
                     'foreignField' => '_id',
                     'as' => 'user',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -44,7 +50,7 @@ public function testLookupStage()
 
     public function testLookupStageWithFieldNameTranslation()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->lookup(CmsComment::class)
                 ->localField('id')
@@ -58,8 +64,8 @@ public function testLookupStageWithFieldNameTranslation()
                     'localField' => '_id',
                     'foreignField' => 'ip',
                     'as' => 'user',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -67,9 +73,9 @@ public function testLookupStageWithFieldNameTranslation()
 
     public function testLookupStageWithClassName()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
-            ->lookup(\Documents\User::class)
+            ->lookup(User::class)
                 ->localField('userId')
                 ->foreignField('_id')
                 ->alias('user');
@@ -81,8 +87,8 @@ public function testLookupStageWithClassName()
                     'localField' => 'userId',
                     'foreignField' => '_id',
                     'as' => 'user',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -96,7 +102,7 @@ public function testLookupStageWithClassName()
 
     public function testLookupStageWithCollectionName()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->lookup('randomCollectionName')
                 ->localField('userId')
@@ -110,8 +116,8 @@ public function testLookupStageWithCollectionName()
                     'localField' => 'userId',
                     'foreignField' => '_id',
                     'as' => 'user',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -124,24 +130,22 @@ public function testLookupStageWithCollectionName()
 
     public function testLookupStageReferenceMany()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->unwind('$users')
             ->lookup('users')
                 ->alias('users');
 
         $expectedPipeline = [
-            [
-                '$unwind' => '$users',
-            ],
+            ['$unwind' => '$users'],
             [
                 '$lookup' => [
                     'from' => 'users',
                     'localField' => 'users',
                     'foreignField' => '_id',
                     'as' => 'users',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -157,24 +161,22 @@ public function testLookupStageReferenceMany()
 
     public function testLookupStageReferenceManyStoreAsRef()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\ReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(ReferenceUser::class);
         $builder
             ->unwind('$referencedUsers')
             ->lookup('referencedUsers')
                 ->alias('users');
 
         $expectedPipeline = [
-            [
-                '$unwind' => '$referencedUsers',
-            ],
+            ['$unwind' => '$referencedUsers'],
             [
                 '$lookup' => [
                     'from' => 'users',
                     'localField' => 'referencedUsers.id',
                     'foreignField' => '_id',
                     'as' => 'users',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -192,7 +194,7 @@ public function testLookupStageReferenceManyWithoutUnwindMongoDB32()
     {
         $this->skipOnMongoDB34('$lookup tests without unwind will not work on MongoDB 3.4.0');
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->lookup('users')
                 ->alias('users');
@@ -204,8 +206,8 @@ public function testLookupStageReferenceManyWithoutUnwindMongoDB32()
                     'localField' => 'users',
                     'foreignField' => '_id',
                     'as' => 'users',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -220,7 +222,7 @@ public function testLookupStageReferenceManyWithoutUnwindMongoDB34()
     {
         $this->requireMongoDB34('$lookup tests with unwind require at least MongoDB 3.4.0');
 
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->lookup('users')
                 ->alias('users');
@@ -232,8 +234,8 @@ public function testLookupStageReferenceManyWithoutUnwindMongoDB34()
                     'localField' => 'users',
                     'foreignField' => '_id',
                     'as' => 'users',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -248,7 +250,7 @@ public function testLookupStageReferenceManyWithoutUnwindMongoDB34()
 
     public function testLookupStageReferenceOneInverse()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\User::class);
+        $builder = $this->dm->createAggregationBuilder(User::class);
         $builder
             ->match()
                 ->field('username')
@@ -258,7 +260,7 @@ public function testLookupStageReferenceOneInverse()
 
         $expectedPipeline = [
             [
-                '$match' => ['username' => 'alcaeus']
+                '$match' => ['username' => 'alcaeus'],
             ],
             [
                 '$lookup' => [
@@ -266,8 +268,8 @@ public function testLookupStageReferenceOneInverse()
                     'localField' => '_id',
                     'foreignField' => 'userId',
                     'as' => 'simpleReferenceOneInverse',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -280,7 +282,7 @@ public function testLookupStageReferenceOneInverse()
 
     public function testLookupStageReferenceManyInverse()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\User::class);
+        $builder = $this->dm->createAggregationBuilder(User::class);
         $builder
             ->match()
                 ->field('username')
@@ -290,7 +292,7 @@ public function testLookupStageReferenceManyInverse()
 
         $expectedPipeline = [
             [
-                '$match' => ['username' => 'alcaeus']
+                '$match' => ['username' => 'alcaeus'],
             ],
             [
                 '$lookup' => [
@@ -298,8 +300,8 @@ public function testLookupStageReferenceManyInverse()
                     'localField' => '_id',
                     'foreignField' => 'users',
                     'as' => 'simpleReferenceManyInverse',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -312,7 +314,7 @@ public function testLookupStageReferenceManyInverse()
 
     public function testLookupStageReferenceOneInverseStoreAsRef()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\User::class);
+        $builder = $this->dm->createAggregationBuilder(User::class);
         $builder
             ->match()
                 ->field('username')
@@ -322,7 +324,7 @@ public function testLookupStageReferenceOneInverseStoreAsRef()
 
         $expectedPipeline = [
             [
-                '$match' => ['username' => 'alcaeus']
+                '$match' => ['username' => 'alcaeus'],
             ],
             [
                 '$lookup' => [
@@ -330,8 +332,8 @@ public function testLookupStageReferenceOneInverseStoreAsRef()
                     'localField' => '_id',
                     'foreignField' => 'referencedUser.id',
                     'as' => 'embeddedReferenceOneInverse',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -344,7 +346,7 @@ public function testLookupStageReferenceOneInverseStoreAsRef()
 
     public function testLookupStageReferenceManyInverseStoreAsRef()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\User::class);
+        $builder = $this->dm->createAggregationBuilder(User::class);
         $builder
             ->match()
                 ->field('username')
@@ -354,7 +356,7 @@ public function testLookupStageReferenceManyInverseStoreAsRef()
 
         $expectedPipeline = [
             [
-                '$match' => ['username' => 'alcaeus']
+                '$match' => ['username' => 'alcaeus'],
             ],
             [
                 '$lookup' => [
@@ -362,8 +364,8 @@ public function testLookupStageReferenceManyInverseStoreAsRef()
                     'localField' => '_id',
                     'foreignField' => 'referencedUsers.id',
                     'as' => 'embeddedReferenceManyInverse',
-                ]
-            ]
+                ],
+            ],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -376,7 +378,7 @@ public function testLookupStageReferenceManyInverseStoreAsRef()
 
     public function testLookupToShardedCollectionThrowsException()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\User::class);
+        $builder = $this->dm->createAggregationBuilder(User::class);
 
         $this->expectException(MappingException::class);
         $builder
@@ -396,22 +398,22 @@ public function testLookupToShardedReferenceThrowsException()
 
     private function insertTestData()
     {
-        $user1 = new \Documents\User();
+        $user1 = new User();
         $user1->setUsername('alcaeus');
-        $user2 = new \Documents\User();
+        $user2 = new User();
         $user2->setUsername('malarzm');
-        $user3 = new \Documents\User();
+        $user3 = new User();
         $user3->setUsername('jmikola');
 
         $this->dm->persist($user1);
         $this->dm->persist($user2);
 
-        $simpleReferenceUser = new \Documents\SimpleReferenceUser();
+        $simpleReferenceUser = new SimpleReferenceUser();
         $simpleReferenceUser->user = $user1;
         $simpleReferenceUser->addUser($user1);
         $simpleReferenceUser->addUser($user2);
 
-        $referenceUser = new \Documents\ReferenceUser();
+        $referenceUser = new ReferenceUser();
         $referenceUser->setReferencedUser($user1);
         $referenceUser->addReferencedUser($user1);
         $referenceUser->addReferencedUser($user2);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/MatchTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/MatchTest.php
index 78ec5e058c..83085bdd50 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/MatchTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/MatchTest.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Match;
 use Doctrine\ODM\MongoDB\Query\Expr;
 use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationTestTrait;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\UTCDateTime;
 
 class MatchTest extends BaseTest
 {
@@ -95,16 +98,18 @@ public function testTypeConversion()
         $builder = $this->dm->createAggregationBuilder('Documents\User');
 
         $date = new \DateTime();
-        $mongoDate = new \MongoDB\BSON\UTCDateTime((int) $date->format('Uv'));
+        $mongoDate = new UTCDateTime((int) $date->format('Uv'));
         $stage = $builder
             ->match()
                 ->field('createdAt')
                 ->lte($date);
 
         $this->assertEquals(
-            ['$match' => [
-                'createdAt' => ['$lte' => $mongoDate]
-            ]],
+            [
+            '$match' => [
+                'createdAt' => ['$lte' => $mongoDate],
+            ],
+            ],
             $stage->getExpression()
         );
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OperatorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OperatorTest.php
index 8160ca99b5..2d457fb4c8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OperatorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OperatorTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Operator;
@@ -39,8 +41,8 @@ public function testExpression()
             [
                 'nested' => [
                     'dayOfMonth' => ['$dayOfMonth' => '$dateField'],
-                    'dayOfWeek' => ['$dayOfWeek' => '$dateField']
-                ]
+                    'dayOfWeek' => ['$dayOfWeek' => '$dateField'],
+                ],
             ],
             $stage->getExpression()
         );
@@ -65,7 +67,7 @@ public function testSwitch()
                         ['case' => ['$eq' => ['$numElements', 1]], 'then' => 'One element given'],
                     ],
                     'default' => ['$concat' => ['$numElements', ' elements given']],
-                ]
+                ],
             ],
             $stage->getExpression()
         );
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OutTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OutTest.php
index eabb01bd36..d254cbe09a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OutTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/OutTest.php
@@ -1,19 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
-class OutTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Sharded\ShardedUser;
+use Documents\SimpleReferenceUser;
+use Documents\User;
+
+class OutTest extends BaseTest
 {
     public function testOutStageWithClassName()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
-            ->out(\Documents\User::class);
+            ->out(User::class);
 
         $expectedPipeline = [
-            [
-                '$out' => 'users'
-            ]
+            ['$out' => 'users'],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -21,14 +26,12 @@ public function testOutStageWithClassName()
 
     public function testOutStageWithCollectionName()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->out('someRandomCollectionName');
 
         $expectedPipeline = [
-            [
-                '$out' => 'someRandomCollectionName'
-            ]
+            ['$out' => 'someRandomCollectionName'],
         ];
 
         $this->assertEquals($expectedPipeline, $builder->getPipeline());
@@ -40,16 +43,16 @@ public function testOutStageWithCollectionName()
      */
     public function testOutStageWithShardedClassName()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
-            ->out(\Documents\Sharded\ShardedUser::class);
+            ->out(ShardedUser::class);
 
         $builder->getPipeline();
     }
 
     public function testSubsequentOutStagesAreOverwritten()
     {
-        $builder = $this->dm->createAggregationBuilder(\Documents\SimpleReferenceUser::class);
+        $builder = $this->dm->createAggregationBuilder(SimpleReferenceUser::class);
         $builder
             ->out('someCollection')
             ->out('otherCollection');
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ProjectTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ProjectTest.php
index 4397480a58..7e8c303c20 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ProjectTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ProjectTest.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Expr;
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Project;
-use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationOperatorsProviderTrait;
 use Doctrine\ODM\MongoDB\Tests\Aggregation\AggregationTestTrait;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function array_combine;
+use function array_map;
 
 class ProjectTest extends BaseTest
 {
@@ -54,7 +57,9 @@ public function provideAccumulators()
     {
         $operators = ['avg', 'max', 'min', 'stdDevPop', 'stdDevSamp', 'sum'];
 
-        return array_combine($operators, array_map(function ($operator) { return [$operator]; }, $operators));
+        return array_combine($operators, array_map(function ($operator) {
+            return [$operator];
+        }, $operators));
     }
 
     /**
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/RedactTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/RedactTest.php
index a5701a0dc7..4e0f3c7bbd 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/RedactTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/RedactTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Redact;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ReplaceRootTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ReplaceRootTest.php
index e2dc41f9fd..583f5b6e61 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ReplaceRootTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ReplaceRootTest.php
@@ -1,27 +1,33 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsComment;
 use Documents\User;
+use MongoDB\BSON\UTCDateTime;
 
-class ReplaceRootTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReplaceRootTest extends BaseTest
 {
     public function testTypeConversion()
     {
         $builder = $this->dm->createAggregationBuilder(User::class);
 
         $dateTime = new \DateTimeImmutable('2000-01-01T00:00Z');
-        $mongoDate = new \MongoDB\BSON\UTCDateTime((int) $dateTime->format('Uv'));
+        $mongoDate = new UTCDateTime((int) $dateTime->format('Uv'));
         $stage = $builder
             ->replaceRoot()
                 ->field('isToday')
                 ->eq('$createdAt', $dateTime);
 
         $this->assertEquals(
-            ['$replaceRoot' => [
+            [
+            '$replaceRoot' => [
                 'isToday' => ['$eq' => ['$createdAt', $mongoDate]],
-            ]],
+            ],
+            ],
             $stage->getExpression()
         );
     }
@@ -31,7 +37,7 @@ public function testTypeConversionWithDirectExpression()
         $builder = $this->dm->createAggregationBuilder(User::class);
 
         $dateTime = new \DateTimeImmutable('2000-01-01T00:00Z');
-        $mongoDate = new \MongoDB\BSON\UTCDateTime((int) $dateTime->format('Uv'));
+        $mongoDate = new UTCDateTime((int) $dateTime->format('Uv'));
         $stage = $builder
             ->replaceRoot(
                 $builder->expr()
@@ -40,9 +46,11 @@ public function testTypeConversionWithDirectExpression()
             );
 
         $this->assertEquals(
-            ['$replaceRoot' => [
+            [
+            '$replaceRoot' => [
                 'isToday' => ['$eq' => ['$createdAt', $mongoDate]],
-            ]],
+            ],
+            ],
             $stage->getExpression()
         );
     }
@@ -57,9 +65,11 @@ public function testFieldNameConversion()
                 ->concat('$authorIp', 'foo');
 
         $this->assertEquals(
-            ['$replaceRoot' => [
+            [
+            '$replaceRoot' => [
                 'someField' => ['$concat' => ['$ip', 'foo']],
-            ]],
+            ],
+            ],
             $stage->getExpression()
         );
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SampleTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SampleTest.php
index 2ebcfa0bb9..f51c2b8bd6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SampleTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SampleTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Sample;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SkipTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SkipTest.php
index 085302cdaa..69f72f272e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SkipTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SkipTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Skip;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortByCountTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortByCountTest.php
index a472d525c2..33a7b1430b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortByCountTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortByCountTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsComment;
 
-class SortByCountTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class SortByCountTest extends BaseTest
 {
     public function testFieldNameConversion()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortTest.php
index b3debaf53f..0cacbdea55 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/SortTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Sort;
@@ -37,20 +39,20 @@ public static function provideSortOptions()
             'singleFieldSeparated' => [
                 ['field' => -1],
                 'field',
-                'desc'
+                'desc',
             ],
             'singleFieldCombined' => [
                 ['field' => -1],
-                ['field' => 'desc']
+                ['field' => 'desc'],
             ],
             'multipleFields' => [
                 ['field' => -1, 'otherField' => 1],
-                ['field' => 'desc', 'otherField' => 'asc']
+                ['field' => 'desc', 'otherField' => 'asc'],
             ],
             'sortMeta' => [
                 ['field' => ['$meta' => 'textScore'], 'invalidField' => -1],
-                ['field' => 'textScore', 'invalidField' => 'nonExistingMetaField']
-            ]
+                ['field' => 'textScore', 'invalidField' => 'nonExistingMetaField'],
+            ],
         ];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/UnwindTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/UnwindTest.php
index 1e1748a835..68fd4d3ee1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/UnwindTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/UnwindTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Aggregation\Stage;
 
 use Doctrine\ODM\MongoDB\Aggregation\Stage\Unwind;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php b/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
index 9e0daffead..ed33d300b7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Configuration;
@@ -9,6 +11,14 @@
 use MongoDB\Client;
 use MongoDB\Model\DatabaseInfo;
 use PHPUnit\Framework\TestCase;
+use const DOCTRINE_MONGODB_DATABASE;
+use const DOCTRINE_MONGODB_SERVER;
+use function array_key_exists;
+use function array_map;
+use function getenv;
+use function in_array;
+use function iterator_to_array;
+use function version_compare;
 
 abstract class BaseTest extends TestCase
 {
@@ -25,7 +35,7 @@ public function setUp()
 
     public function tearDown()
     {
-        if ( ! $this->dm) {
+        if (! $this->dm) {
             return;
         }
 
@@ -75,14 +85,14 @@ protected function createMetadataDriverImpl()
     protected function createTestDocumentManager()
     {
         $config = $this->getConfiguration();
-        $client = new Client(getenv("DOCTRINE_MONGODB_SERVER") ?: DOCTRINE_MONGODB_SERVER, [], ['typeMap' => ['root' => 'array', 'document' => 'array']]);
+        $client = new Client(getenv('DOCTRINE_MONGODB_SERVER') ?: DOCTRINE_MONGODB_SERVER, [], ['typeMap' => ['root' => 'array', 'document' => 'array']]);
 
         return DocumentManager::create($client, $config);
     }
 
     protected function getServerVersion()
     {
-        $result = $this->dm->getClient()->selectDatabase(DOCTRINE_MONGODB_DATABASE)->command(array('buildInfo' => 1))->toArray()[0];
+        $result = $this->dm->getClient()->selectDatabase(DOCTRINE_MONGODB_DATABASE)->command(['buildInfo' => 1])->toArray()[0];
 
         return $result['version'];
     }
@@ -90,11 +100,11 @@ protected function getServerVersion()
     protected function skipTestIfNotSharded($className)
     {
         $result = $this->dm->getDocumentDatabase($className)->command(['listCommands' => true])->toArray()[0];
-        if (!$result['ok']) {
+        if (! $result['ok']) {
             $this->markTestSkipped('Could not check whether server supports sharding');
         }
 
-        if (!array_key_exists('shardCollection', $result['commands'])) {
+        if (! array_key_exists('shardCollection', $result['commands'])) {
             $this->markTestSkipped('Test skipped because server does not support sharding');
         }
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/ConfigurationTest.php b/tests/Doctrine/ODM/MongoDB/Tests/ConfigurationTest.php
index 1ede172e93..ea4e03dd75 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/ConfigurationTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/ConfigurationTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Configuration;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/DocumentManagerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/DocumentManagerTest.php
index 886b881735..c51b85246f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/DocumentManagerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/DocumentManagerTest.php
@@ -1,14 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-use Doctrine\ODM\MongoDB\Tests\Mocks\DocumentManagerMock;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\MongoDBException;
 use Documents\CmsPhonenumber;
+use Documents\Tournament\ParticipantSolo;
+use Documents\User;
+use MongoDB\BSON\ObjectId;
 use MongoDB\Client;
+use function get_class;
 
-class DocumentManagerTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class DocumentManagerTest extends BaseTest
 {
     public function testCustomRepository()
     {
@@ -77,7 +83,7 @@ public function testGetFilterCollection()
 
     public function testGetPartialReference()
     {
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
         $user = $this->dm->getPartialReference('Documents\CmsUser', $id);
         $this->assertTrue($this->dm->contains($user));
         $this->assertEquals($id, $user->id);
@@ -93,13 +99,13 @@ public function testDocumentManagerIsClosedAccessor()
 
     public function dataMethodsAffectedByNoObjectArguments()
     {
-        return array(
-            array('persist'),
-            array('remove'),
-            array('merge'),
-            array('refresh'),
-            array('detach')
-        );
+        return [
+            ['persist'],
+            ['remove'],
+            ['merge'],
+            ['refresh'],
+            ['detach'],
+        ];
     }
 
     /**
@@ -114,13 +120,13 @@ public function testThrowsExceptionOnNonObjectValues($methodName)
 
     public function dataAffectedByErrorIfClosedException()
     {
-        return array(
-            array('flush'),
-            array('persist'),
-            array('remove'),
-            array('merge'),
-            array('refresh'),
-        );
+        return [
+            ['flush'],
+            ['persist'],
+            ['remove'],
+            ['merge'],
+            ['refresh'],
+        ];
     }
 
     /**
@@ -129,7 +135,7 @@ public function dataAffectedByErrorIfClosedException()
      */
     public function testAffectedByErrorIfClosedException($methodName)
     {
-        $this->expectException(\Doctrine\ODM\MongoDB\MongoDBException::class);
+        $this->expectException(MongoDBException::class);
         $this->expectExceptionMessage('closed');
 
         $this->dm->close();
@@ -146,7 +152,7 @@ public function testAffectedByErrorIfClosedException($methodName)
      */
     public function testCannotCreateDbRefWithoutId()
     {
-        $d = new \Documents\User();
+        $d = new User();
         $this->dm->createReference($d, ['storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF]);
     }
 
@@ -158,7 +164,7 @@ public function testCreateDbRefWithNonNullEmptyId()
 
         $dbRef = $this->dm->createReference($phonenumber, ['storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF, 'targetDocument' => CmsPhonenumber::class]);
 
-        $this->assertSame(array('$ref' => 'CmsPhonenumber', '$id' => 0), $dbRef);
+        $this->assertSame(['$ref' => 'CmsPhonenumber', '$id' => 0], $dbRef);
     }
 
     /**
@@ -168,7 +174,7 @@ public function testCreateDbRefWithNonNullEmptyId()
     public function testDisriminatedSimpleReferenceFails()
     {
         $d = new WrongSimpleRefDocument();
-        $r = new \Documents\Tournament\ParticipantSolo('Maciej');
+        $r = new ParticipantSolo('Maciej');
         $this->dm->persist($r);
         $class = $this->dm->getClassMetadata(get_class($d));
         $this->dm->createReference($r, $class->associationMappings['ref']);
@@ -176,13 +182,13 @@ public function testDisriminatedSimpleReferenceFails()
 
     public function testDifferentStoreAsDbReferences()
     {
-        $r = new \Documents\User();
+        $r = new User();
         $this->dm->persist($r);
         $d = new ReferenceStoreAsDocument();
         $class = $this->dm->getClassMetadata(get_class($d));
 
         $dbRef = $this->dm->createReference($r, $class->associationMappings['ref1']);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $dbRef);
+        $this->assertInstanceOf(ObjectId::class, $dbRef);
 
         $dbRef = $this->dm->createReference($r, $class->associationMappings['ref2']);
         $this->assertCount(2, $dbRef);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/DocumentRepositoryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/DocumentRepositoryTest.php
index 69a37a888b..2543b1aeb1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/DocumentRepositoryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/DocumentRepositoryTest.php
@@ -1,10 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Criteria;
-use Doctrine\ODM\MongoDB\LockMode;
 use Documents\Account;
 use Documents\Address;
 use Documents\Developer;
@@ -13,6 +14,7 @@
 use Documents\SubProject;
 use Documents\User;
 use MongoDB\BSON\ObjectId;
+use const DOCTRINE_MONGODB_DATABASE;
 
 class DocumentRepositoryTest extends BaseTest
 {
@@ -38,7 +40,7 @@ public function testFindByRefOneFull()
             ->getUnitOfWork()
             ->getDocumentPersister(User::class)
             ->prepareQueryOrNewObj(['account' => $account]);
-        $expectedQuery = ['account.$id' => new \MongoDB\BSON\ObjectId($account->getId())];
+        $expectedQuery = ['account.$id' => new ObjectId($account->getId())];
         $this->assertEquals($expectedQuery, $query);
 
         $this->assertSame($user, $this->dm->getRepository(User::class)->findOneBy(['account' => $account]));
@@ -59,8 +61,8 @@ public function testFindByRefOneWithoutTargetDocumentFull()
             ->prepareQueryOrNewObj(['user' => $user]);
         $expectedQuery = [
             'user.$ref' => 'users',
-            'user.$id' => new \MongoDB\BSON\ObjectId($user->getId()),
-            'user.$db' => DOCTRINE_MONGODB_DATABASE
+            'user.$id' => new ObjectId($user->getId()),
+            'user.$db' => DOCTRINE_MONGODB_DATABASE,
         ];
         $this->assertEquals($expectedQuery, $query);
 
@@ -82,7 +84,7 @@ public function testFindByRefOneWithoutTargetDocumentStoredAsDbRef()
             ->prepareQueryOrNewObj(['userDbRef' => $user]);
         $expectedQuery = [
             'userDbRef.$ref' => 'users',
-            'userDbRef.$id' => new ObjectId($user->getId())
+            'userDbRef.$id' => new ObjectId($user->getId()),
         ];
         $this->assertEquals($expectedQuery, $query);
 
@@ -101,7 +103,7 @@ public function testFindDiscriminatedByRefManyFull()
             ->getUnitOfWork()
             ->getDocumentPersister(Developer::class)
             ->prepareQueryOrNewObj(['projects' => $project]);
-        $expectedQuery = ['projects' => ['$elemMatch' => ['$id' => new \MongoDB\BSON\ObjectId($project->getId())]]];
+        $expectedQuery = ['projects' => ['$elemMatch' => ['$id' => new ObjectId($project->getId())]]];
         $this->assertEquals($expectedQuery, $query);
 
         $this->assertSame($developer, $this->dm->getRepository(Developer::class)->findOneBy(['projects' => $project]));
@@ -146,7 +148,7 @@ public function testFindByRefManyFull()
         $expectedQuery = [
             'groups' => [
                 '$elemMatch' => [
-                    '$id' => new \MongoDB\BSON\ObjectId($group->getId()),
+                    '$id' => new ObjectId($group->getId()),
                 ],
             ],
         ];
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleCallbacksTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleCallbacksTest.php
index 0d56379b5a..a42632a880 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleCallbacksTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleCallbacksTest.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Events;
 
 use Doctrine\ODM\MongoDB\Event;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\UnitOfWork;
 
-class LifecycleCallbacksTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class LifecycleCallbacksTest extends BaseTest
 {
     private function createUser($name = 'jon', $fullName = 'Jonathan H. Wage')
     {
@@ -24,7 +27,7 @@ public function testPreUpdateChangingValue()
         $user = $this->createUser();
         $this->dm->clear();
 
-        $user = $this->dm->find(__NAMESPACE__.'\User', $user->id);
+        $user = $this->dm->find(__NAMESPACE__ . '\User', $user->id);
         $this->assertInstanceOf('DateTime', $user->createdAt);
         $this->assertInstanceOf('DateTime', $user->profile->createdAt);
 
@@ -33,7 +36,7 @@ public function testPreUpdateChangingValue()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->find(__NAMESPACE__.'\User', $user->id);
+        $user = $this->dm->find(__NAMESPACE__ . '\User', $user->id);
         $this->assertInstanceOf('DateTime', $user->updatedAt);
         $this->assertInstanceOf('DateTime', $user->profile->updatedAt);
     }
@@ -61,7 +64,7 @@ public function testPreUpdate()
         $this->assertTrue($user->postUpdate);
         $this->assertTrue($user->profile->postUpdate);
     }
-    
+
     public function testPreFlush()
     {
         $user = $this->createUser();
@@ -78,7 +81,7 @@ public function testPreLoadAndPostLoad()
         $user = $this->createUser();
         $this->dm->clear();
 
-        $user = $this->dm->find(__NAMESPACE__.'\User', $user->id);
+        $user = $this->dm->find(__NAMESPACE__ . '\User', $user->id);
 
         $this->assertTrue($user->preLoad);
         $this->assertTrue($user->profile->preLoad);
@@ -126,7 +129,7 @@ public function testEmbedManyEvent()
         $this->assertTrue($profile->postUpdate);
 
         $this->dm->clear();
-        $user = $this->dm->find(__NAMESPACE__.'\User', $user->id);
+        $user = $this->dm->find(__NAMESPACE__ . '\User', $user->id);
         $profile = $user->profiles[0];
 
         $this->assertTrue($profile->preLoad);
@@ -172,10 +175,10 @@ public function testMultipleLevelsOfEmbedded()
         $this->assertTrue($profile->postUpdate);
 
         $this->dm->clear();
-        $user = $this->dm->find(__NAMESPACE__.'\User', $user->id);
+        $user = $this->dm->find(__NAMESPACE__ . '\User', $user->id);
         $profile = $user->profile->profile;
         $profile->name = '2nd level changed again';
-        
+
         $profile2 = new Profile();
         $profile2->name = 'test';
         $user->profiles[] = $profile2;
@@ -206,12 +209,12 @@ public function testMultipleLevelsOfEmbedded()
         $this->assertTrue($user->profiles[0]->preRemove);
         $this->assertTrue($user->profiles[0]->postRemove);
     }
-    
+
     public function testReferences()
     {
         $user = $this->createUser();
         $user2 = $this->createUser('maciej', 'Maciej Malarz');
-        
+
         $user->friends[] = $user2;
         $this->dm->flush();
 
@@ -250,10 +253,10 @@ class User extends BaseDocument
     public $profile;
 
     /** @ODM\EmbedMany(targetDocument="Profile") */
-    public $profiles = array();
-    
+    public $profiles = [];
+
     /** @ODM\ReferenceMany(targetDocument="User") */
-    public $friends = array();
+    public $friends = [];
 }
 
 /** @ODM\Document */
@@ -358,7 +361,7 @@ public function postLoad(Event\LifecycleEventArgs $e)
     {
         $this->postLoad = true;
     }
-    
+
     /** @ODM\PreFlush */
     public function preFlush(Event\PreFlushEventArgs $e)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleListenersTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleListenersTest.php
index 5838255eef..f019c2b48d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleListenersTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Events/LifecycleListenersTest.php
@@ -1,18 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Events;
 
 use Doctrine\ODM\MongoDB\Event\PostCollectionLoadEventArgs;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class LifecycleListenersTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class LifecycleListenersTest extends BaseTest
 {
     private function getDocumentManager()
     {
         $this->listener = new MyEventListener();
         $evm = $this->dm->getEventManager();
-        $events = array(
+        $events = [
             Events::prePersist,
             Events::postPersist,
             Events::preUpdate,
@@ -21,7 +25,7 @@ private function getDocumentManager()
             Events::postLoad,
             Events::preRemove,
             Events::postRemove,
-        );
+        ];
         $evm->addEventListener($events, $this->listener);
         return $this->dm;
     }
@@ -35,55 +39,55 @@ public function testLifecycleListeners()
         $dm->persist($test);
         $dm->flush();
 
-        $called = array(
-            Events::prePersist => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postPersist => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument')
-        );
+        $called = [
+            Events::prePersist => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postPersist => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $test->embedded[0] = new TestEmbeddedDocument();
         $test->embedded[0]->name = 'cool';
         $dm->flush();
         $dm->clear();
 
-        $called = array(
-            Events::prePersist => array('Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'),
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postPersist => array('Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument')
-        );
+        $called = [
+            Events::prePersist => ['Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postPersist => ['Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
-        $document = $dm->find(__NAMESPACE__.'\TestDocument', $test->id);
+        $document = $dm->find(__NAMESPACE__ . '\TestDocument', $test->id);
         $document->embedded->initialize();
-        $called = array(
-            Events::preLoad => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'),
-            Events::postLoad => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument')
-        );
+        $called = [
+            Events::preLoad => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+            Events::postLoad => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $document->embedded[0]->name = 'changed';
         $dm->flush();
 
-        $called = array(
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument')
-        );
+        $called = [
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $dm->remove($document);
         $dm->flush();
 
-        $called = array(
-            Events::preRemove => array('Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postRemove => array('Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestDocument')
-        );
+        $called = [
+            Events::preRemove => ['Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postRemove => ['Doctrine\ODM\MongoDB\Tests\Events\TestEmbeddedDocument', 'Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $test = new TestDocument();
         $test->name = 'test';
@@ -91,19 +95,19 @@ public function testLifecycleListeners()
         $test->embedded[0]->name = 'cool';
         $dm->persist($test);
         $dm->flush();
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $test->name = 'cool';
         $dm->flush();
 
         $dm->clear();
 
-        $called = array(
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument')
-        );
+        $called = [
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
     }
 
     public function testMultipleLevelsOfEmbeddedDocsPrePersist()
@@ -117,29 +121,29 @@ public function testMultipleLevelsOfEmbeddedDocsPrePersist()
         $dm->flush();
         $dm->clear();
 
-        $test = $dm->find(__NAMESPACE__.'\TestProfile', $test->id);
-        $this->listener->called = array();
+        $test = $dm->find(__NAMESPACE__ . '\TestProfile', $test->id);
+        $this->listener->called = [];
 
         $test->image->thumbnails[] = new Thumbnail('Thumbnail #1');
 
         $dm->flush();
-        $called = array(
-            Events::prePersist => array('Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'),
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image'),
-            Events::postPersist => array('Doctrine\ODM\MongoDB\Tests\Events\Thumbnail')
-        );
+        $called = [
+            Events::prePersist => ['Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'],
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image'],
+            Events::postPersist => ['Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $test->image->thumbnails[0]->name = 'ok';
         $dm->flush();
-        $called = array(
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image', 'Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image', 'Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'),
-        );
+        $called = [
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image', 'Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestProfile', 'Doctrine\ODM\MongoDB\Tests\Events\Image', 'Doctrine\ODM\MongoDB\Tests\Events\Thumbnail'],
+        ];
         $this->assertEquals($called, $this->listener->called);
-        $this->listener->called = array();
+        $this->listener->called = [];
     }
 
     public function testChangeToReferenceFieldTriggersEvents()
@@ -153,29 +157,29 @@ public function testChangeToReferenceFieldTriggersEvents()
         $dm->persist($profile);
         $dm->flush();
         $dm->clear();
-        $this->listener->called = array();
+        $this->listener->called = [];
 
-        $called = array(
-            Events::preUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-            Events::postUpdate => array('Doctrine\ODM\MongoDB\Tests\Events\TestDocument'),
-        );
+        $called = [
+            Events::preUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+            Events::postUpdate => ['Doctrine\ODM\MongoDB\Tests\Events\TestDocument'],
+        ];
 
         $document = $dm->getRepository(get_class($document))->find($document->id);
         $profile = $dm->getRepository(get_class($profile))->find($profile->id);
-        $this->listener->called = array();
+        $this->listener->called = [];
         $document->profile = $profile;
         $dm->flush();
         $dm->clear();
         $this->assertEquals($called, $this->listener->called, 'Changing ReferenceOne field did not dispatched proper events.');
-        $this->listener->called = array();
+        $this->listener->called = [];
 
         $document = $dm->getRepository(get_class($document))->find($document->id);
         $profile = $dm->getRepository(get_class($profile))->find($profile->id);
-        $this->listener->called = array();
+        $this->listener->called = [];
         $document->profiles[] = $profile;
         $dm->flush();
         $this->assertEquals($called, $this->listener->called, 'Changing ReferenceMany field did not dispatched proper events.');
-        $this->listener->called = array();
+        $this->listener->called = [];
     }
 
     public function testPostCollectionLoad()
@@ -205,7 +209,7 @@ public function testPostCollectionLoad()
 
 class MyEventListener
 {
-    public $called = array();
+    public $called = [];
 
     public function __call($method, $args)
     {
@@ -302,7 +306,7 @@ class Image
     public $name;
 
     /** @ODM\EmbedMany(targetDocument="Thumbnail") */
-    public $thumbnails = array();
+    public $thumbnails = [];
 
     public function __construct($name)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Events/PreLoadEventArgsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Events/PreLoadEventArgsTest.php
index e86b909233..2824411042 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Events/PreLoadEventArgsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Events/PreLoadEventArgsTest.php
@@ -1,17 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Events;
 
 use Doctrine\ODM\MongoDB\Event\PreLoadEventArgs;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Group;
 
-class PreLoadEventArgsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class PreLoadEventArgsTest extends BaseTest
 {
     public function testGetData()
     {
         $document = new Group('test');
         $dm = $this->dm;
-        $data = array('id' => '1234', 'name' => 'test');
+        $data = ['id' => '1234', 'name' => 'test'];
 
         $eventArgs = new PreLoadEventArgs($document, $dm, $data);
         $eventArgsData =& $eventArgs->getData();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Events/PreUpdateEventArgsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Events/PreUpdateEventArgsTest.php
index 5991eac539..93ac8d549b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Events/PreUpdateEventArgsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Events/PreUpdateEventArgsTest.php
@@ -1,15 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Events;
 
 use Doctrine\ODM\MongoDB\Event\PreUpdateEventArgs;
 use Doctrine\ODM\MongoDB\Events;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Article;
 use Documents\Book;
 use Documents\Chapter;
 use Documents\Page;
+use function get_class;
+use function in_array;
 
-class PreUpdateEventArgsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class PreUpdateEventArgsTest extends BaseTest
 {
     public function testChangeSetIsUpdated()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/AlsoLoadTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/AlsoLoadTest.php
index 4716435efc..a14c03a665 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/AlsoLoadTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/AlsoLoadTest.php
@@ -1,24 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\Functional\AlsoLoad;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function explode;
 
-class AlsoLoadTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class AlsoLoadTest extends BaseTest
 {
     public function testPropertyAlsoLoadDoesNotInterfereWithBasicHydration()
     {
-        $document = array(
+        $document = [
             'foo' => 'foo',
             'bar' => 'bar',
             'baz' => null,
             'zip' => 'zip',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('foo', $document->foo, '"foo" gets its own value and ignores "bar" and "zip"');
         $this->assertEquals('bar', $document->bar, '"bar" is hydrated normally');
@@ -27,11 +30,11 @@ public function testPropertyAlsoLoadDoesNotInterfereWithBasicHydration()
 
     public function testPropertyAlsoLoadMayOverwriteDefaultPropertyValue()
     {
-        $document = array('zip' => 'zip');
+        $document = ['zip' => 'zip'];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('zip', $document->zap, '"zap" gets value from "zip", overwriting its default value');
         $this->assertEquals('zip', $document->zip, '"zip" is hydrated normally');
@@ -39,14 +42,14 @@ public function testPropertyAlsoLoadMayOverwriteDefaultPropertyValue()
 
     public function testPropertyAlsoLoadShortCircuitsAfterFirstFieldIsFound()
     {
-        $document = array(
+        $document = [
             'bar' => null,
             'zip' => 'zip',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals(null, $document->foo, '"foo" gets null value from "bar" and ignores "zip"');
         $this->assertEquals('zip', $document->baz, '"baz" gets value from "zip" and ignores "bar"');
@@ -56,11 +59,11 @@ public function testPropertyAlsoLoadShortCircuitsAfterFirstFieldIsFound()
 
     public function testPropertyAlsoLoadChecksMultipleFields()
     {
-        $document = array('zip' => 'zip');
+        $document = ['zip' => 'zip'];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('zip', $document->foo, '"foo" gets value from "zip" since "bar" was missing');
         $this->assertNull($document->bar, '"bar" is not hydrated');
@@ -69,14 +72,14 @@ public function testPropertyAlsoLoadChecksMultipleFields()
 
     public function testPropertyAlsoLoadBeatsMethodAlsoLoad()
     {
-        $document = array(
+        $document = [
             'testNew' => 'testNew',
             'testOld' => 'testOld',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('testNew', $document->test, '"test" gets value from "testNew"');
         $this->assertEquals('testNew', $document->testNew, '"testNew" is hydrated normally');
@@ -85,14 +88,14 @@ public function testPropertyAlsoLoadBeatsMethodAlsoLoad()
 
     public function testMethodAlsoLoadDoesNotInterfereWithBasicHydration()
     {
-        $document = array(
+        $document = [
             'firstName' => 'Jonathan',
             'name' => 'Kris Wallsmith',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('Jonathan', $document->firstName, '"firstName" gets value from exploded "name" but is overwritten with normal hydration');
         $this->assertEquals('Wallsmith', $document->lastName, '"lastName" gets value from exploded "name"');
@@ -101,11 +104,11 @@ public function testMethodAlsoLoadDoesNotInterfereWithBasicHydration()
 
     public function testMethodAlsoLoadMayOverwriteDefaultPropertyValue()
     {
-        $document = array('testOld' => null);
+        $document = ['testOld' => null];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertNull($document->test, '"test" gets value from "testOld", overwriting its default value');
         $this->assertNull($document->testOld, '"testOld" is hydrated normally"');
@@ -113,16 +116,16 @@ public function testMethodAlsoLoadMayOverwriteDefaultPropertyValue()
 
     public function testMethodAlsoLoadShortCircuitsAfterFirstFieldIsFound()
     {
-        $document = array(
+        $document = [
             'name' => 'Jonathan Wage',
             'fullName' => 'Kris Wallsmith',
             'testOld' => 'testOld',
             'testOlder' => 'testOlder',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertEquals('Jonathan Wage', $document->name, '"name" is hydrated normally');
         $this->assertEquals('Kris Wallsmith', $document->fullName, '"fullName" is hydrated normally');
@@ -136,14 +139,14 @@ public function testMethodAlsoLoadShortCircuitsAfterFirstFieldIsFound()
 
     public function testMethodAlsoLoadChecksMultipleFields()
     {
-        $document = array(
+        $document = [
             'fullName' => 'Kris Wallsmith',
             'testOlder' => 'testOlder',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadDocument')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadDocument')->findOneBy([]);
 
         $this->assertNull($document->name, '"name" is not hydrated');
         $this->assertEquals('Kris Wallsmith', $document->fullName, '"fullName" is hydrated normally');
@@ -176,16 +179,16 @@ public function testNotSaved()
 
     public function testMethodAlsoLoadParentInheritance()
     {
-        $document = array(
+        $document = [
             'buzz' => 'buzz',
             'test' => 'test',
             'testOld' => 'testOld',
             'testOlder' => 'testOlder',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadChild')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadChild')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadChild')->findOneBy([]);
 
         $this->assertEquals('buzz', $document->fizz, '"fizz" gets value from "buzz"');
         $this->assertEquals('test', $document->test, '"test" is hydrated normally, since "testOldest" was missing and parent method was overridden');
@@ -193,14 +196,14 @@ public function testMethodAlsoLoadParentInheritance()
 
     public function testMethodAlsoLoadGrandparentInheritance()
     {
-        $document = array(
+        $document = [
             'buzz' => 'buzz',
             'testReallyOldest' => 'testReallyOldest',
-        );
+        ];
 
         $this->dm->getDocumentCollection(__NAMESPACE__ . '\AlsoLoadGrandchild')->insertOne($document);
 
-        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadGrandchild')->findOneBy(array());
+        $document = $this->dm->getRepository(__NAMESPACE__ . '\AlsoLoadGrandchild')->findOneBy([]);
 
         $this->assertEquals('buzz', $document->fizz, '"fizz" gets value from "buzz"');
         $this->assertEquals('testReallyOldest', $document->test, '"test" gets value from "testReallyOldest"');
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/AtomicSetTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/AtomicSetTest.php
index ffe2535440..704d481b3a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/AtomicSetTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/AtomicSetTest.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Tests\QueryLogger;
 use Documents\Book;
 use Documents\Chapter;
@@ -11,13 +14,15 @@
 use Documents\Page;
 use Documents\Phonebook;
 use Documents\Phonenumber;
+use MongoDB\BSON\ObjectId;
+use function get_class;
 
 /**
  * CollectionPersister will throw exception when collection with atomicSet
  * or atomicSetArray should be handled by it. If no exception was thrown it
  * means that collection update was handled by DocumentPersister.
  */
-class AtomicSetTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class AtomicSetTest extends BaseTest
 {
     /**
      * @var QueryLogger
@@ -27,7 +32,7 @@ class AtomicSetTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
     protected function getConfiguration()
     {
         $this->markTestSkipped('mongodb-driver: query logging does not exist');
-        if ( ! isset($this->ql)) {
+        if (! isset($this->ql)) {
             $this->ql = new QueryLogger();
         }
 
@@ -51,7 +56,7 @@ public function testAtomicInsertAndUpdate()
         $this->assertCount(1, $user->phonenumbers);
         $this->assertEquals('12345678', $user->phonenumbers[0]->getPhonenumber());
 
-        $user->surname = "Malarz";
+        $user->surname = 'Malarz';
         $user->phonenumbers[] = new Phonenumber('87654321');
         $this->ql->clear();
         $this->dm->flush();
@@ -69,7 +74,7 @@ public function testAtomicInsertAndUpdate()
     public function testAtomicUpsert()
     {
         $user = new AtomicSetUser('Maciej');
-        $user->id = new \MongoDB\BSON\ObjectId();
+        $user->id = new ObjectId();
         $user->phonenumbers[] = new Phonenumber('12345678');
         $this->dm->persist($user);
         $this->dm->flush();
@@ -99,7 +104,7 @@ public function testAtomicCollectionUnset($clearWith)
         $this->assertCount(1, $user->phonenumbers);
         $this->assertEquals('12345678', $user->phonenumbers[0]->getPhonenumber());
 
-        $user->surname = "Malarz";
+        $user->surname = 'Malarz';
         $user->phonenumbers = $clearWith;
         $this->ql->clear();
         $this->dm->flush();
@@ -114,11 +119,11 @@ public function testAtomicCollectionUnset($clearWith)
 
     public function provideAtomicCollectionUnset()
     {
-        return array(
-            array(null),
-            array(array()),
-            array(new ArrayCollection()),
-        );
+        return [
+            [null],
+            [[]],
+            [new ArrayCollection()],
+        ];
     }
 
     public function testAtomicCollectionClearAndUpdate()
@@ -250,7 +255,7 @@ public function testAtomicCollectionWithAnotherNested()
         $this->assertCount(1, $publicBook->getPhonenumbers());
         $this->assertEquals('10203040', $publicBook->getPhonenumbers()->get(0)->getPhonenumber());
     }
-    
+
     public function testWeNeedToGoDeeper()
     {
         $user = new AtomicSetUser('Maciej');
@@ -413,7 +418,7 @@ public function testAtomicSetUpdatesAllNestedCollectionsInOneQuery()
 
         // Simulate another PHP request which loads this record and tries to add an embedded document two levels deep...
         $this->dm->clear();
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
 
         // Now we add a new "page" to the only chapter in this book.
         $firstChapter = $book->chapters->first();
@@ -425,8 +430,8 @@ public function testAtomicSetUpdatesAllNestedCollectionsInOneQuery()
         $this->assertCount(1, $this->ql, 'Adding a page to the first chapter of the book requires one query');
 
         // this is failing if lifecycle callback postUpdate is recomputing change set
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
-        $this->assertEquals(2, $book->chapters->first()->pages->count(), "Two page objects are expected in the first chapter of the book.");
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
+        $this->assertEquals(2, $book->chapters->first()->pages->count(), 'Two page objects are expected in the first chapter of the book.');
     }
 
     public function testReplacementOfEmbedManyElements()
@@ -441,10 +446,10 @@ public function testReplacementOfEmbedManyElements()
 
         // Simulate another PHP request which loads this record.
         $this->dm->clear();
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
 
         $firstChapter = $book->chapters->first();
-        $firstChapter->name = "First chapter A";
+        $firstChapter->name = 'First chapter A';
 
         // Developers commonly attempt to replace the contents of an EmbedMany with a new ArrayCollection like this:
         $replacementChapters = new ArrayCollection();
@@ -456,7 +461,7 @@ public function testReplacementOfEmbedManyElements()
 
         // Simulate another PHP request.
         $this->dm->clear();
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
 
         // Verify we see chapters A and B.
         $this->assertEquals('First chapter A', $book->chapters[0]->name);
@@ -472,9 +477,9 @@ public function testReplacementOfIdentifiedEmbedManyElements()
         $this->dm->flush();
         $this->dm->clear();
 
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
         $firstChapter = $book->identifiedChapters->first();
-        $firstChapter->name = "First chapter A";
+        $firstChapter->name = 'First chapter A';
         $replacementChapters = new ArrayCollection();
         $replacementChapters->add($firstChapter);
         $replacementChapters->add(new IdentifiedChapter('Second chapter B'));
@@ -483,7 +488,7 @@ public function testReplacementOfIdentifiedEmbedManyElements()
         $this->dm->flush();
         $this->dm->clear();
 
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
         $this->assertEquals('First chapter A', $book->identifiedChapters[0]->name);
         $this->assertEquals('Second chapter B', $book->identifiedChapters[1]->name);
     }
@@ -500,18 +505,18 @@ public function testOnlyEmbeddedDocumentUpdated()
 
         // Simulate another PHP request which loads this record.
         $this->dm->clear();
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
 
         // Modify the chapter's name.
-        $book->chapters->first()->name = "First chapter A";
+        $book->chapters->first()->name = 'First chapter A';
 
         $this->dm->flush();
 
         // Simulate another PHP request & verify the change was saved.
         $this->dm->clear();
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
 
-        $this->assertEquals('First chapter A', $book->chapters[0]->name, "The chapter title failed to update.");
+        $this->assertEquals('First chapter A', $book->chapters[0]->name, 'The chapter title failed to update.');
     }
 
     public function testUpdatedEmbeddedDocumentAndDirtyCollectionInside()
@@ -523,9 +528,9 @@ public function testUpdatedEmbeddedDocumentAndDirtyCollectionInside()
         $this->dm->flush();
         $this->dm->clear();
 
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
         $firstChapter = $book->chapters->first();
-        $firstChapter->name = "Apple";
+        $firstChapter->name = 'Apple';
 
         // Add some pages.
         $firstChapter->pages->add(new Page(1));
@@ -534,7 +539,7 @@ public function testUpdatedEmbeddedDocumentAndDirtyCollectionInside()
         $this->dm->flush();
         $this->dm->clear();
 
-        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(array('_id' => $book->id));
+        $book = $this->dm->getRepository(Book::CLASSNAME)->findOneBy(['_id' => $book->id]);
         $this->assertEquals(2, $book->chapters->first()->pages->count());
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/BidirectionalInheritanceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/BidirectionalInheritanceTest.php
index 9733054f58..20149af9c0 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/BidirectionalInheritanceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/BidirectionalInheritanceTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/BinDataTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/BinDataTest.php
index c9eff662cc..fcda580090 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/BinDataTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/BinDataTest.php
@@ -1,9 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\Binary;
+use function get_class;
 
 class BinDataTest extends BaseTest
 {
@@ -17,23 +21,23 @@ public function testBinData($field, $data, $type)
         $this->dm->persist($test);
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(get_class($test))->findOne(array());
-        $this->assertInstanceOf(\MongoDB\BSON\Binary::class, $check[$field]);
+        $check = $this->dm->getDocumentCollection(get_class($test))->findOne([]);
+        $this->assertInstanceOf(Binary::class, $check[$field]);
         $this->assertEquals($type, $check[$field]->getType());
         $this->assertEquals($data, $check[$field]->getData());
     }
 
     public function provideData()
     {
-        return array(
-            array('bin', 'test', \MongoDB\BSON\Binary::TYPE_GENERIC),
-            array('binFunc', 'test', \MongoDB\BSON\Binary::TYPE_FUNCTION),
-            array('binByteArray', 'test', \MongoDB\BSON\Binary::TYPE_OLD_BINARY),
-            array('binUUID', 'testtesttesttest', \MongoDB\BSON\Binary::TYPE_OLD_UUID),
-            array('binUUIDRFC4122', '1234567890ABCDEF', \MongoDB\BSON\Binary::TYPE_UUID),
-            array('binMD5', 'test', \MongoDB\BSON\Binary::TYPE_MD5),
-            array('binCustom', 'test', \MongoDB\BSON\Binary::TYPE_USER_DEFINED),
-        );
+        return [
+            ['bin', 'test', Binary::TYPE_GENERIC],
+            ['binFunc', 'test', Binary::TYPE_FUNCTION],
+            ['binByteArray', 'test', Binary::TYPE_OLD_BINARY],
+            ['binUUID', 'testtesttesttest', Binary::TYPE_OLD_UUID],
+            ['binUUIDRFC4122', '1234567890ABCDEF', Binary::TYPE_UUID],
+            ['binMD5', 'test', Binary::TYPE_MD5],
+            ['binCustom', 'test', Binary::TYPE_USER_DEFINED],
+        ];
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionPersisterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionPersisterTest.php
index 49158759ad..550cff8cba 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionPersisterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionPersisterTest.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Persisters\CollectionPersister;
 use Doctrine\ODM\MongoDB\Persisters\PersistenceBuilder;
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
 class CollectionPersisterTest extends BaseTest
 {
@@ -13,9 +17,9 @@ public function testDeleteReferenceMany()
     {
         $persister = $this->getCollectionPersister();
         $user = $this->getTestUser('jwage');
-        $persister->delete($user->phonenumbers, array());
+        $persister->delete($user->phonenumbers, []);
 
-        $user = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $user = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertArrayNotHasKey('phonenumbers', $user, 'Test that the phonenumbers field was deleted');
     }
 
@@ -23,9 +27,9 @@ public function testDeleteEmbedMany()
     {
         $persister = $this->getCollectionPersister();
         $user = $this->getTestUser('jwage');
-        $persister->delete($user->categories, array());
+        $persister->delete($user->categories, []);
 
-        $user = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $user = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertArrayNotHasKey('categories', $user, 'Test that the categories field was deleted');
     }
 
@@ -34,18 +38,18 @@ public function testDeleteNestedEmbedMany()
         $persister = $this->getCollectionPersister();
         $user = $this->getTestUser('jwage');
 
-        $persister->delete($user->categories[0]->children[0]->children, array());
-        $persister->delete($user->categories[0]->children[1]->children, array());
+        $persister->delete($user->categories[0]->children[0]->children, []);
+        $persister->delete($user->categories[0]->children[1]->children, []);
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
 
         $this->assertFalse(isset($check['categories']['0']['children'][0]['children']));
         $this->assertFalse(isset($check['categories']['0']['children'][1]['children']));
 
-        $persister->delete($user->categories[0]->children, array());
-        $persister->delete($user->categories[1]->children, array());
+        $persister->delete($user->categories[0]->children, []);
+        $persister->delete($user->categories[1]->children, []);
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
 
         $this->assertFalse(isset($check['categories'][0]['children']), 'Test that the nested children categories field was deleted');
         $this->assertTrue(isset($check['categories'][0]), 'Test that the category with the children still exists');
@@ -70,7 +74,7 @@ public function testDeleteRows()
 
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
 
         $this->assertFalse(isset($check['phonenumbers'][0]));
         $this->assertFalse(isset($check['phonenumbers'][1]));
@@ -85,7 +89,7 @@ public function testDeleteRows()
         unset($user->categories[1]);
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertFalse(isset($check['categories'][0]));
         $this->assertFalse(isset($check['categories'][1]));
     }
@@ -97,7 +101,7 @@ public function testInsertRows()
         $user->phonenumbers[] = new CollectionPersisterPhonenumber('6155139185');
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertCount(4, $check['phonenumbers']);
         $this->assertEquals((string) $check['phonenumbers'][2]['$id'], $user->phonenumbers[2]->id);
         $this->assertEquals((string) $check['phonenumbers'][3]['$id'], $user->phonenumbers[3]->id);
@@ -106,7 +110,7 @@ public function testInsertRows()
         $user->categories[] = new CollectionPersisterCategory('Test');
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertCount(4, $check['categories']);
 
         $user->categories[3]->children[0] = new CollectionPersisterCategory('Test');
@@ -115,7 +119,7 @@ public function testInsertRows()
         $user->categories[3]->children[1]->children[1] = new CollectionPersisterCategory('Test');
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(array('username' => 'jwage'));
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterUser')->findOne(['username' => 'jwage']);
         $this->assertCount(2, $check['categories'][3]['children']);
         $this->assertCount(2, $check['categories'][3]['children']['1']['children']);
     }
@@ -168,7 +172,7 @@ public function testNestedEmbedManySetStrategy()
         $this->dm->persist($post);
         $this->dm->flush();
 
-        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(array('post' => 'postA'));
+        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(['post' => 'postA']);
 
         $this->assertCount(1, $doc['comments']);
         $this->assertEquals($commentA->comment, $doc['comments']['a']['comment']);
@@ -189,7 +193,7 @@ public function testNestedEmbedManySetStrategy()
         $this->dm->persist($post);
         $this->dm->flush();
 
-        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(array('post' => 'postA'));
+        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(['post' => 'postA']);
 
         $this->assertCount(2, $doc['comments']);
         $this->assertEquals($commentA->comment, $doc['comments']['a']['comment']);
@@ -209,7 +213,7 @@ public function testNestedEmbedManySetStrategy()
         $this->dm->persist($post);
         $this->dm->flush();
 
-        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(array('post' => 'postA'));
+        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(['post' => 'postA']);
 
         $this->assertCount(2, $doc['comments']);
         $this->assertEquals($commentA->comment, $doc['comments']['a']['comment']);
@@ -226,7 +230,7 @@ public function testNestedEmbedManySetStrategy()
         $this->dm->persist($post);
         $this->dm->flush();
 
-        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(array('post' => 'postA'));
+        $doc = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CollectionPersisterPost')->findOne(['post' => 'postA']);
 
         $this->assertCount(1, $doc['comments']);
         $this->assertEquals($commentA->comment, $doc['comments']['a']['comment']);
@@ -248,8 +252,8 @@ public function testFindBySetStrategyKey()
         $this->dm->persist($post);
         $this->dm->flush();
 
-        $this->assertSame($post, $this->dm->getRepository(get_class($post))->findOneBy(array('comments.a.by' => 'userA')));
-        $this->assertSame($post, $this->dm->getRepository(get_class($post))->findOneBy(array('comments.a.comments.b.by' => 'userB')));
+        $this->assertSame($post, $this->dm->getRepository(get_class($post))->findOneBy(['comments.a.by' => 'userA']));
+        $this->assertSame($post, $this->dm->getRepository(get_class($post))->findOneBy(['comments.a.comments.b.by' => 'userB']));
     }
 }
 
@@ -263,10 +267,10 @@ class CollectionPersisterUser
     public $username;
 
     /** @ODM\EmbedMany(targetDocument="CollectionPersisterCategory") */
-    public $categories = array();
+    public $categories = [];
 
     /** @ODM\ReferenceMany(targetDocument="CollectionPersisterPhonenumber", cascade={"persist"}) */
-    public $phonenumbers = array();
+    public $phonenumbers = [];
 }
 
 /** @ODM\EmbeddedDocument */
@@ -276,7 +280,7 @@ class CollectionPersisterCategory
     public $name;
 
     /** @ODM\EmbedMany(targetDocument="CollectionPersisterCategory") */
-    public $children = array();
+    public $children = [];
 
     public function __construct($name)
     {
@@ -303,42 +307,40 @@ public function __construct($phonenumber)
 class CollectionPersisterPost
 {
   /** @ODM\Id */
-  public $id;
+    public $id;
 
   /** @ODM\Field(type="string") */
-  public $post;
+    public $post;
 
   /** @ODM\EmbedMany(targetDocument="CollectionPersisterComment", strategy="set") */
-  public $comments = array();
-
-  function __construct($post)
-  {
-    $this->comments = new \Doctrine\Common\Collections\ArrayCollection();
-    $this->post = $post;
-  }
-
+    public $comments = [];
 
+    function __construct($post)
+    {
+        $this->comments = new ArrayCollection();
+        $this->post = $post;
+    }
 }
 
 /** @ODM\EmbeddedDocument */
 class CollectionPersisterComment
 {
   /** @ODM\Id */
-  public $id;
+    public $id;
 
   /** @ODM\Field(type="string") */
-  public $comment;
+    public $comment;
 
   /** @ODM\Field(type="string") */
-  public $by;
+    public $by;
 
   /** @ODM\EmbedMany(targetDocument="CollectionPersisterComment", strategy="set") */
-  public $comments = array();
-
-  function __construct($comment, $by)
-  {
-    $this->comments = new \Doctrine\Common\Collections\ArrayCollection();
-    $this->comment = $comment;
-    $this->by = $by;
-  }
+    public $comments = [];
+
+    function __construct($comment, $by)
+    {
+        $this->comments = new ArrayCollection();
+        $this->comment = $comment;
+        $this->by = $by;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionsTest.php
index 9760945d20..c027e0f5dd 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CollectionsTest.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Bars\Bar;
 use Documents\Bars\Location;
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
-class CollectionsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CollectionsTest extends BaseTest
 {
     public function testCollections()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CommitImprovementTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CommitImprovementTest.php
index eb64b3b2aa..10f426db89 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CommitImprovementTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CommitImprovementTest.php
@@ -1,16 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\EventSubscriber;
 use Doctrine\ODM\MongoDB\Events;
+use Doctrine\ODM\MongoDB\LockException;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Tests\QueryLogger;
 use Documents\Phonebook;
 use Documents\Phonenumber;
 use Documents\User;
 use Documents\VersionedUser;
+use function get_class;
 
-class CommitImprovementTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CommitImprovementTest extends BaseTest
 {
     /**
      * @var Doctrine\ODM\MongoDB\Tests\QueryLogger
@@ -20,7 +25,7 @@ class CommitImprovementTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
     protected function getConfiguration()
     {
         $this->markTestSkipped('mongodb-driver: query logging does not exist');
-        if ( ! isset($this->ql)) {
+        if (! isset($this->ql)) {
             $this->ql = new QueryLogger();
         }
 
@@ -68,8 +73,7 @@ public function testCollectionsAreUpdatedJustAfterOwningDocument()
         $troll->setVersion(3);
         try {
             $this->dm->flush();
-        } catch (\Doctrine\ODM\MongoDB\LockException $ex) {
-
+        } catch (LockException $ex) {
         }
 
         $this->dm->clear();
@@ -137,22 +141,22 @@ public function testSchedulingCollectionDeletionAfterSchedulingForUpdate()
 
 class PhonenumberMachine implements EventSubscriber
 {
-    private $numbers = array('12345678', '87654321');
+    private $numbers = ['12345678', '87654321'];
 
     private $numberId = 0;
 
     public function getSubscribedEvents()
     {
-        return array(
+        return [
             Events::postPersist,
             Events::postUpdate,
-        );
+        ];
     }
 
     public function __call($eventName, $args)
     {
         $document = $args[0]->getDocument();
-        if ( ! ($document instanceof User)) {
+        if (! ($document instanceof User)) {
             return;
         }
         // hey I just met you, and this is crazy!
@@ -165,8 +169,8 @@ public function __call($eventName, $args)
             // prove that even this won't break our flow
             $dm = $args[0]->getDocumentManager();
             $dm->getUnitOfWork()->recomputeSingleDocumentChangeSet(
-                    $dm->getClassMetadata(get_class($document)),
-                    $document
+                $dm->getClassMetadata(get_class($document)),
+                $document
             );
         }
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
index af5452a53f..a8817aaea4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
@@ -1,17 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
-use Doctrine\ODM\MongoDB\Configuration;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\PersistentCollection;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\File;
 use Documents\ProfileNotify;
+use function get_class;
 
-class CustomCollectionsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CustomCollectionsTest extends BaseTest
 {
     public function testMappingNamespaceIsAdded()
     {
@@ -35,12 +38,12 @@ public function testCollectionClassHasToImplementCommonInterface()
     {
         $cm = new ClassMetadata('stdClass');
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'many',
             'collectionClass' => 'stdClass',
-        ));
+        ]);
     }
 
     public function testGeneratedClassExtendsBaseCollection()
@@ -234,14 +237,14 @@ class MyEmbedsCollection extends ArrayCollection
 {
     public function getByName($name)
     {
-        return $this->filter(function($item) use ($name) {
+        return $this->filter(function ($item) use ($name) {
             return $item->name === $name;
         });
     }
 
     public function getEnabled()
     {
-        return $this->filter(function($item) {
+        return $this->filter(function ($item) {
             return $item->enabled;
         });
     }
@@ -258,7 +261,7 @@ class MyDocumentsCollection extends ArrayCollection
 {
     public function havingEmbeds()
     {
-        return $this->filter(function($item) {
+        return $this->filter(function ($item) {
             return $item->coll->count();
         });
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomFieldNameTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomFieldNameTest.php
index 724cb9bbc1..3cde001660 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomFieldNameTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomFieldNameTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class CustomFieldNameTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CustomFieldNameTest extends BaseTest
 {
     public function testInsertSetsLoginInsteadOfUsername()
     {
@@ -14,7 +17,7 @@ public function testInsertSetsLoginInsteadOfUsername()
         $this->dm->persist($test);
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection(__NAMESPACE__.'\CustomFieldName')->findOne();
+        $test = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CustomFieldName')->findOne();
         $this->assertArrayHasKey('login', $test);
         $this->assertEquals('test', $test['login']);
     }
@@ -28,7 +31,7 @@ public function testHydration()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->find(__NAMESPACE__.'\CustomFieldName', $test->id);
+        $test = $this->dm->find(__NAMESPACE__ . '\CustomFieldName', $test->id);
         $this->assertNotNull($test);
         $this->assertEquals('test', $test->username);
     }
@@ -42,12 +45,12 @@ public function testUpdateSetsLoginInsteadOfUsername()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->find(__NAMESPACE__.'\CustomFieldName', $test->id);
+        $test = $this->dm->find(__NAMESPACE__ . '\CustomFieldName', $test->id);
 
         $test->username = 'ok';
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection(__NAMESPACE__.'\CustomFieldName')->findOne();
+        $test = $this->dm->getDocumentCollection(__NAMESPACE__ . '\CustomFieldName')->findOne();
         $this->assertArrayHasKey('login', $test);
         $this->assertEquals('ok', $test['login']);
     }
@@ -61,7 +64,7 @@ public function testFindOneQueryIsPrepared()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository(__NAMESPACE__.'\CustomFieldName')->findOneBy(array('username' => 'test'));
+        $test = $this->dm->getRepository(__NAMESPACE__ . '\CustomFieldName')->findOneBy(['username' => 'test']);
         $this->assertNotNull($test);
         $this->assertEquals('test', $test->username);
     }
@@ -75,7 +78,7 @@ public function testFindQueryIsPrepared()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository(__NAMESPACE__.'\CustomFieldName')->findOneBy(array('username' => 'test'));
+        $test = $this->dm->getRepository(__NAMESPACE__ . '\CustomFieldName')->findOneBy(['username' => 'test']);
         $this->assertNotNull($test);
         $this->assertEquals('test', $test->username);
     }
@@ -89,7 +92,7 @@ public function testQueryBuilderAndDqlArePrepared()
         $this->dm->flush();
         $this->dm->clear();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\CustomFieldName')->field('username')->equals('test');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\CustomFieldName')->field('username')->equals('test');
         $query = $qb->getQuery();
         $test = $query->getSingleResult();
         $this->assertNotNull($test);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
index 84965a972f..2303452bda 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
@@ -1,12 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Account;
 use Documents\CustomUser;
 use Documents\User;
+use function count;
 
-class CustomIdTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CustomIdTest extends BaseTest
 {
     public function testSetId()
     {
@@ -74,11 +78,11 @@ public function testBatchInsertCustomId()
 
         unset($user1, $user2, $user3);
 
-        $users = $this->dm->getRepository("Documents\User")->findAll();
+        $users = $this->dm->getRepository('Documents\User')->findAll();
 
         $this->assertCount(2, $users);
 
-        $results = array();
+        $results = [];
         foreach ($users as $user) {
             if ($user->getId() === 'userId') {
                 $results['userId'] = true;
@@ -87,7 +91,7 @@ public function testBatchInsertCustomId()
             $results['ids'][] = $user->getId();
         }
 
-        $users = $this->dm->getRepository("Documents\CustomUser")->findAll();
+        $users = $this->dm->getRepository('Documents\CustomUser')->findAll();
 
         $this->assertCount(1, $users);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
index 0ae8ce35c8..753339ac24 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
@@ -1,12 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Types\ClosureToPHP;
 use Doctrine\ODM\MongoDB\Types\Type;
+use function array_map;
+use function array_values;
+use function is_array;
 
-class CustomTypeTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class CustomTypeTest extends BaseTest
 {
     public static function setUpBeforeClass()
     {
@@ -16,7 +22,7 @@ public static function setUpBeforeClass()
     public function testCustomTypeValueConversions()
     {
         $country = new Country();
-        $country->nationalHolidays = array(new \DateTime(), new \DateTime());
+        $country->nationalHolidays = [new \DateTime(), new \DateTime()];
 
         $this->dm->persist($country);
         $this->dm->flush();
@@ -52,13 +58,13 @@ public function convertToDatabaseValue($value)
             return null;
         }
 
-        if (!is_array($value)) {
+        if (! is_array($value)) {
             throw new CustomTypeException('Array expected.');
         }
 
         $converter = Type::getType('date');
 
-        $value = array_map(function($date) use ($converter) {
+        $value = array_map(function ($date) use ($converter) {
             return $converter->convertToDatabaseValue($date);
         }, array_values($value));
 
@@ -71,13 +77,13 @@ public function convertToPHPValue($value)
             return null;
         }
 
-        if (!is_array($value)) {
+        if (! is_array($value)) {
             throw new CustomTypeException('Array expected.');
         }
 
         $converter = Type::getType('date');
 
-        $value = array_map(function($date) use ($converter) {
+        $value = array_map(function ($date) use ($converter) {
             return $converter->convertToPHPValue($date);
         }, array_values($value));
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DatabasesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DatabasesTest.php
index 88e27c0f51..2ed1efc757 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DatabasesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DatabasesTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class DatabasesTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class DatabasesTest extends BaseTest
 {
     public function testCustomDatabase()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php
index 7ac937700b..a243f19284 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php
@@ -1,13 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\Account;
-use Documents\Address;
-use Documents\Phonenumber;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
+use MongoDB\BSON\UTCDateTime;
+use const PHP_INT_SIZE;
+use function get_class;
+use function time;
 
-class DateTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class DateTest extends BaseTest
 {
     public function testDates()
     {
@@ -40,7 +44,7 @@ public function testDateInstanceChangeDoesNotCauseUpdateIfValueIsTheSame($oldVal
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository(get_class($user))->findOneBy(array());
+        $user = $this->dm->getRepository(get_class($user))->findOneBy([]);
         $user->setCreatedAt($newValue);
         $this->dm->getUnitOfWork()->computeChangeSets();
         $changeset = $this->dm->getUnitOfWork()->getDocumentChangeset($user);
@@ -49,14 +53,14 @@ public function testDateInstanceChangeDoesNotCauseUpdateIfValueIsTheSame($oldVal
 
     public function provideEquivalentDates()
     {
-        return array(
-            array(new \DateTime('1985-09-01 00:00:00'), new \DateTime('1985-09-01 00:00:00')),
-            array(new \DateTime('2012-07-11T14:55:14-04:00'), new \DateTime('2012-07-11T19:55:14+01:00')),
-            array(new \DateTime('@1342033881'), new \MongoDB\BSON\UTCDateTime(1342033881000)),
-            array(\DateTime::createFromFormat('U.u', '100000000.123'), new \MongoDB\BSON\UTCDateTime(100000000123)),
-            array(\DateTime::createFromFormat('U.u', '100000000.123000'), new \MongoDB\BSON\UTCDateTime(100000000123)),
-            array(new \MongoDB\BSON\UTCDateTime(100000000123), \DateTime::createFromFormat('U.u', '100000000.123')),
-        );
+        return [
+            [new \DateTime('1985-09-01 00:00:00'), new \DateTime('1985-09-01 00:00:00')],
+            [new \DateTime('2012-07-11T14:55:14-04:00'), new \DateTime('2012-07-11T19:55:14+01:00')],
+            [new \DateTime('@1342033881'), new UTCDateTime(1342033881000)],
+            [\DateTime::createFromFormat('U.u', '100000000.123'), new UTCDateTime(100000000123)],
+            [\DateTime::createFromFormat('U.u', '100000000.123000'), new UTCDateTime(100000000123)],
+            [new UTCDateTime(100000000123), \DateTime::createFromFormat('U.u', '100000000.123')],
+        ];
     }
 
     public function testDateInstanceValueChangeDoesCauseUpdateIfValueIsTheSame()
@@ -67,7 +71,7 @@ public function testDateInstanceValueChangeDoesCauseUpdateIfValueIsTheSame()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository(get_class($user))->findOneBy(array());
+        $user = $this->dm->getRepository(get_class($user))->findOneBy([]);
         $user->getCreatedAt()->setTimestamp(time() - 3600);
 
         $this->dm->getUnitOfWork()->computeChangeSets();
@@ -92,10 +96,10 @@ public function testOldDate()
 
         $this->dm->clear();
 
-        $test = $this->dm->getDocumentCollection('Documents\User')->findOne(array('username' => 'datetest2'));
+        $test = $this->dm->getDocumentCollection('Documents\User')->findOne(['username' => 'datetest2']);
         $this->assertArrayHasKey('createdAt', $test);
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'datetest2'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'datetest2']);
         $this->assertInstanceOf(\DateTime::class, $user->getCreatedAt());
         $this->assertEquals('1900-01-01', $user->getCreatedAt()->format('Y-m-d'));
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DetachedDocumentTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DetachedDocumentTest.php
index 271bb5dea5..84273dbc54 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DetachedDocumentTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DetachedDocumentTest.php
@@ -1,17 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\Tests\ORM\Functional;
 
-use Documents\CmsUser;
-use Documents\CmsPhonenumber;
-use Documents\CmsAddress;
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\CmsAddress;
+use Documents\CmsPhonenumber;
+use Documents\CmsUser;
+use function get_class;
+use function serialize;
+use function unserialize;
 
-class DetachedDocumentTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class DetachedDocumentTest extends BaseTest
 {
     public function testSimpleDetachMerge()
     {
-        $user = new CmsUser;
+        $user = new CmsUser();
         $user->name = 'Roman';
         $user->username = 'romanb';
         $user->status = 'dev';
@@ -36,12 +42,12 @@ public function testSimpleDetachMerge()
 
     public function testSerializeUnserializeModifyMerge()
     {
-        $user = new CmsUser;
+        $user = new CmsUser();
         $user->name = 'Guilherme';
         $user->username = 'gblanco';
         $user->status = 'developer';
 
-        $ph1 = new CmsPhonenumber;
+        $ph1 = new CmsPhonenumber();
         $ph1->phonenumber = '1234';
         $user->addPhonenumber($ph1);
 
@@ -58,7 +64,7 @@ public function testSerializeUnserializeModifyMerge()
 
         $user = unserialize($serialized);
 
-        $ph2 = new CmsPhonenumber;
+        $ph2 = new CmsPhonenumber();
         $ph2->phonenumber = '56789';
         $user->addPhonenumber($ph2);
         $this->assertCount(2, $user->getPhonenumbers());
@@ -84,31 +90,14 @@ public function testSerializeUnserializeModifyMerge()
         $this->assertTrue($this->dm->contains($phonenumbers[1]));
     }
 
-    /**
-     * @group DDC-203
-     */
-    public function testDetachedEntityThrowsExceptionOnFlush()
-    {
-        $ph = new CmsPhonenumber();
-        $ph->phonenumber = '12345';
-        $this->dm->persist($ph);
-        $this->dm->flush();
-        $this->dm->clear();
-        $this->dm->persist($ph);
-        try {
-            $this->dm->flush();
-            $this->fail();
-        } catch (\Exception $expected) {}
-    }
-
     public function testUninitializedLazyAssociationsAreIgnoredOnMerge()
     {
-        $user = new CmsUser;
+        $user = new CmsUser();
         $user->name = 'Guilherme';
         $user->username = 'gblanco';
         $user->status = 'developer';
 
-        $address = new CmsAddress;
+        $address = new CmsAddress();
         $address->city = 'Berlin';
         $address->country = 'Germany';
         $address->street = 'Sesamestreet';
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
index fda5dfb3c0..d261ac66f9 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class ReferenceDiscriminatorsDefaultValueTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferenceDiscriminatorsDefaultValueTest extends BaseTest
 {
     public function setUp()
     {
@@ -20,7 +23,7 @@ public function testLoadDocumentWithDefaultValue()
         $this->dm->persist($firstChildWithoutDiscriminator = new ChildDocumentWithoutDiscriminator('firstWithoutDiscriminator'));
         $this->dm->persist($secondChildWithoutDiscriminator = new ChildDocumentWithoutDiscriminator('firstWithoutDiscriminator'));
 
-        $children = array($firstChildWithoutDiscriminator, $secondChildWithoutDiscriminator);
+        $children = [$firstChildWithoutDiscriminator, $secondChildWithoutDiscriminator];
         $this->dm->persist($parentWithoutDiscriminator = new ParentDocumentWithoutDiscriminator($children));
 
         $this->dm->flush();
@@ -52,7 +55,7 @@ public function testLoadDocumentWithDifferentChild()
         $this->dm->persist($firstChildWithDiscriminator = new ChildDocumentWithDiscriminatorComplex('firstWithDiscriminator', 'veryComplex'));
         $this->dm->persist($secondChildWithDiscriminator = new ChildDocumentWithDiscriminatorSimple('secondWithDiscriminator'));
 
-        $children = array($firstChildWithDiscriminator, $secondChildWithDiscriminator);
+        $children = [$firstChildWithDiscriminator, $secondChildWithDiscriminator];
         $this->dm->persist($parentWithDiscriminator = new ParentDocumentWithDiscriminator($children));
 
         $this->dm->flush();
@@ -203,7 +206,6 @@ class ParentDocumentWithDiscriminator extends ParentDocument
  */
 class ChildDocumentWithDiscriminator extends ChildDocument
 {
-
 }
 
 /** @ODM\Document(collection="discriminator_child") */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
index 5b2c96586b..8030b8fd34 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
@@ -1,12 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\LockException;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 use MongoDB\Collection;
 
-class DocumentPersisterTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class DocumentPersisterTest extends BaseTest
 {
     private $class;
 
@@ -24,8 +29,8 @@ public function setUp()
         $collection = $this->dm->getDocumentCollection($this->class);
         $collection->drop();
 
-        foreach (array('a', 'b', 'c', 'd') as $name) {
-            $document = array('dbName' => $name);
+        foreach (['a', 'b', 'c', 'd'] as $name) {
+            $document = ['dbName' => $name];
             $collection->insertOne($document);
         }
 
@@ -42,15 +47,15 @@ public function testExecuteUpsertShouldNeverReplaceDocuments()
         $this->dm->persist($document);
         $this->dm->flush();
 
-        $updatedData = $this->dm->getDocumentCollection($this->class)->findOne(array('_id' => $originalData['_id']));
+        $updatedData = $this->dm->getDocumentCollection($this->class)->findOne(['_id' => $originalData['_id']]);
 
         $this->assertEquals($originalData, $updatedData);
     }
 
     public function testExistsReturnsTrueForExistentDocuments()
     {
-        foreach (array('a', 'b', 'c', 'd') as $name) {
-            $document = $this->documentPersister->load(array('name' => $name));
+        foreach (['a', 'b', 'c', 'd'] as $name) {
+            $document = $this->documentPersister->load(['name' => $name]);
             $this->assertTrue($this->documentPersister->exists($document));
         }
     }
@@ -58,17 +63,17 @@ public function testExistsReturnsTrueForExistentDocuments()
     public function testExistsReturnsFalseForNonexistentDocuments()
     {
         $document = new DocumentPersisterTestDocument();
-        $document->id = new \MongoDB\BSON\ObjectId();
+        $document->id = new ObjectId();
 
         $this->assertFalse($this->documentPersister->exists($document));
     }
 
     public function testLoadPreparesCriteriaAndSort()
     {
-        $criteria = array('name' => array('$in' => array('a', 'b')));
-        $sort = array('name' => -1);
+        $criteria = ['name' => ['$in' => ['a', 'b']]];
+        $sort = ['name' => -1];
 
-        $document = $this->documentPersister->load($criteria, null, array(), 0, $sort);
+        $document = $this->documentPersister->load($criteria, null, [], 0, $sort);
 
         $this->assertInstanceOf($this->class, $document);
         $this->assertEquals('b', $document->name);
@@ -76,8 +81,8 @@ public function testLoadPreparesCriteriaAndSort()
 
     public function testLoadAllPreparesCriteriaAndSort()
     {
-        $criteria = array('name' => array('$in' => array('a', 'b')));
-        $sort = array('name' => -1);
+        $criteria = ['name' => ['$in' => ['a', 'b']]];
+        $sort = ['name' => -1];
 
         $cursor = $this->documentPersister->loadAll($criteria, $sort);
         $documents = $cursor->toArray();
@@ -90,9 +95,9 @@ public function testLoadAllPreparesCriteriaAndSort()
 
     public function testLoadAllWithSortLimitAndSkip()
     {
-        $sort = array('name' => -1);
+        $sort = ['name' => -1];
 
-        $cursor = $this->documentPersister->loadAll(array(), $sort, 1, 2);
+        $cursor = $this->documentPersister->loadAll([], $sort, 1, 2);
         $documents = $cursor->toArray();
 
         $this->assertInstanceOf($this->class, $documents[0]);
@@ -110,18 +115,18 @@ public function testPrepareFieldName($fieldName, $expected)
 
     public function getTestPrepareFieldNameData()
     {
-        return array(
-            array('name', 'dbName'),
-            array('association', 'associationName'),
-            array('association.id', 'associationName._id'),
-            array('association.nested', 'associationName.nestedName'),
-            array('association.nested.$id', 'associationName.nestedName.$id'),
-            array('association.nested._id', 'associationName.nestedName._id'),
-            array('association.nested.id', 'associationName.nestedName._id'),
-            array('association.nested.association.nested.$id', 'associationName.nestedName.associationName.nestedName.$id'),
-            array('association.nested.association.nested.id', 'associationName.nestedName.associationName.nestedName._id'),
-            array('association.nested.association.nested.firstName', 'associationName.nestedName.associationName.nestedName.firstName'),
-        );
+        return [
+            ['name', 'dbName'],
+            ['association', 'associationName'],
+            ['association.id', 'associationName._id'],
+            ['association.nested', 'associationName.nestedName'],
+            ['association.nested.$id', 'associationName.nestedName.$id'],
+            ['association.nested._id', 'associationName.nestedName._id'],
+            ['association.nested.id', 'associationName.nestedName._id'],
+            ['association.nested.association.nested.$id', 'associationName.nestedName.associationName.nestedName.$id'],
+            ['association.nested.association.nested.id', 'associationName.nestedName.associationName.nestedName._id'],
+            ['association.nested.association.nested.firstName', 'associationName.nestedName.associationName.nestedName.firstName'],
+        ];
     }
 
     /**
@@ -132,8 +137,8 @@ public function testPrepareQueryOrNewObjWithHashId($hashId)
         $class = DocumentPersisterTestHashIdDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $value = array('_id' => $hashId);
-        $expected = array('_id' => (object) $hashId);
+        $value = ['_id' => $hashId];
+        $expected = ['_id' => (object) $hashId];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -146,39 +151,39 @@ public function testPrepareQueryOrNewObjWithHashIdAndInOperators($hashId)
         $class = DocumentPersisterTestHashIdDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $value = array('_id' => array('$exists' => true));
-        $expected = array('_id' => array('$exists' => true));
+        $value = ['_id' => ['$exists' => true]];
+        $expected = ['_id' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('_id' => array('$elemMatch' => $hashId));
-        $expected = array('_id' => array('$elemMatch' => (object) $hashId));
+        $value = ['_id' => ['$elemMatch' => $hashId]];
+        $expected = ['_id' => ['$elemMatch' => (object) $hashId]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('_id' => array('$in' => array($hashId)));
-        $expected = array('_id' => array('$in' => array((object) $hashId)));
+        $value = ['_id' => ['$in' => [$hashId]]];
+        $expected = ['_id' => ['$in' => [(object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('_id' => array('$not' => array('$elemMatch' => $hashId)));
-        $expected = array('_id' => array('$not' => array('$elemMatch' => (object) $hashId)));
+        $value = ['_id' => ['$not' => ['$elemMatch' => $hashId]]];
+        $expected = ['_id' => ['$not' => ['$elemMatch' => (object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('_id' => array('$not' => array('$in' => array($hashId))));
-        $expected = array('_id' => array('$not' => array('$in' => array((object) $hashId))));
+        $value = ['_id' => ['$not' => ['$in' => [$hashId]]]];
+        $expected = ['_id' => ['$not' => ['$in' => [(object) $hashId]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
 
     public function provideHashIdentifiers()
     {
-        return array(
-            array(array('key' => 'value')),
-            array(array(0 => 'first', 1 => 'second')),
-            array(array('$ref' => 'ref', '$id' => 'id')),
-        );
+        return [
+            [['key' => 'value']],
+            [[0 => 'first', 1 => 'second']],
+            [['$ref' => 'ref', '$id' => 'id']],
+        ];
     }
 
     public function testPrepareQueryOrNewObjWithSimpleReferenceToTargetDocumentWithNormalIdType()
@@ -186,35 +191,35 @@ public function testPrepareQueryOrNewObjWithSimpleReferenceToTargetDocumentWithN
         $class = DocumentPersisterTestHashIdDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
 
-        $value = array('simpleRef' => (string) $id);
-        $expected = array('simpleRef' => $id);
+        $value = ['simpleRef' => (string) $id];
+        $expected = ['simpleRef' => $id];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$exists' => true));
-        $expected = array('simpleRef' => array('$exists' => true));
+        $value = ['simpleRef' => ['$exists' => true]];
+        $expected = ['simpleRef' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$elemMatch' => (string) $id));
-        $expected = array('simpleRef' => array('$elemMatch' => $id));
+        $value = ['simpleRef' => ['$elemMatch' => (string) $id]];
+        $expected = ['simpleRef' => ['$elemMatch' => $id]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$in' => array((string) $id)));
-        $expected = array('simpleRef' => array('$in' => array($id)));
+        $value = ['simpleRef' => ['$in' => [(string) $id]]];
+        $expected = ['simpleRef' => ['$in' => [$id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$not' => array('$elemMatch' => (string) $id)));
-        $expected = array('simpleRef' => array('$not' => array('$elemMatch' => $id)));
+        $value = ['simpleRef' => ['$not' => ['$elemMatch' => (string) $id]]];
+        $expected = ['simpleRef' => ['$not' => ['$elemMatch' => $id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$not' => array('$in' => array((string) $id))));
-        $expected = array('simpleRef' => array('$not' => array('$in' => array($id))));
+        $value = ['simpleRef' => ['$not' => ['$in' => [(string) $id]]]];
+        $expected = ['simpleRef' => ['$not' => ['$in' => [$id]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -227,33 +232,33 @@ public function testPrepareQueryOrNewObjWithSimpleReferenceToTargetDocumentWithH
         $class = DocumentPersisterTestDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $value = array('simpleRef' => $hashId);
-        $expected = array('simpleRef' => (object) $hashId);
+        $value = ['simpleRef' => $hashId];
+        $expected = ['simpleRef' => (object) $hashId];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$exists' => true));
-        $expected = array('simpleRef' => array('$exists' => true));
+        $value = ['simpleRef' => ['$exists' => true]];
+        $expected = ['simpleRef' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$elemMatch' => $hashId));
-        $expected = array('simpleRef' => array('$elemMatch' => (object) $hashId));
+        $value = ['simpleRef' => ['$elemMatch' => $hashId]];
+        $expected = ['simpleRef' => ['$elemMatch' => (object) $hashId]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$in' => array($hashId)));
-        $expected = array('simpleRef' => array('$in' => array((object) $hashId)));
+        $value = ['simpleRef' => ['$in' => [$hashId]]];
+        $expected = ['simpleRef' => ['$in' => [(object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$not' => array('$elemMatch' => $hashId)));
-        $expected = array('simpleRef' => array('$not' => array('$elemMatch' => (object) $hashId)));
+        $value = ['simpleRef' => ['$not' => ['$elemMatch' => $hashId]]];
+        $expected = ['simpleRef' => ['$not' => ['$elemMatch' => (object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('simpleRef' => array('$not' => array('$in' => array($hashId))));
-        $expected = array('simpleRef' => array('$not' => array('$in' => array((object) $hashId))));
+        $value = ['simpleRef' => ['$not' => ['$in' => [$hashId]]]];
+        $expected = ['simpleRef' => ['$not' => ['$in' => [(object) $hashId]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -263,35 +268,35 @@ public function testPrepareQueryOrNewObjWithDBRefReferenceToTargetDocumentWithNo
         $class = DocumentPersisterTestHashIdDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
 
-        $value = array('complexRef.id' => (string) $id);
-        $expected = array('complexRef.$id' => $id);
+        $value = ['complexRef.id' => (string) $id];
+        $expected = ['complexRef.$id' => $id];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$exists' => true));
-        $expected = array('complexRef.$id' => array('$exists' => true));
+        $value = ['complexRef.id' => ['$exists' => true]];
+        $expected = ['complexRef.$id' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$elemMatch' => (string) $id));
-        $expected = array('complexRef.$id' => array('$elemMatch' => $id));
+        $value = ['complexRef.id' => ['$elemMatch' => (string) $id]];
+        $expected = ['complexRef.$id' => ['$elemMatch' => $id]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$in' => array((string) $id)));
-        $expected = array('complexRef.$id' => array('$in' => array($id)));
+        $value = ['complexRef.id' => ['$in' => [(string) $id]]];
+        $expected = ['complexRef.$id' => ['$in' => [$id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$not' => array('$elemMatch' => (string) $id)));
-        $expected = array('complexRef.$id' => array('$not' => array('$elemMatch' => $id)));
+        $value = ['complexRef.id' => ['$not' => ['$elemMatch' => (string) $id]]];
+        $expected = ['complexRef.$id' => ['$not' => ['$elemMatch' => $id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$not' => array('$in' => array((string) $id))));
-        $expected = array('complexRef.$id' => array('$not' => array('$in' => array($id))));
+        $value = ['complexRef.id' => ['$not' => ['$in' => [(string) $id]]]];
+        $expected = ['complexRef.$id' => ['$not' => ['$in' => [$id]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -304,33 +309,33 @@ public function testPrepareQueryOrNewObjWithDBRefReferenceToTargetDocumentWithHa
         $class = DocumentPersisterTestDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $value = array('complexRef.id' => $hashId);
-        $expected = array('complexRef.$id' => (object) $hashId);
+        $value = ['complexRef.id' => $hashId];
+        $expected = ['complexRef.$id' => (object) $hashId];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$exists' => true));
-        $expected = array('complexRef.$id' => array('$exists' => true));
+        $value = ['complexRef.id' => ['$exists' => true]];
+        $expected = ['complexRef.$id' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$elemMatch' => $hashId));
-        $expected = array('complexRef.$id' => array('$elemMatch' => (object) $hashId));
+        $value = ['complexRef.id' => ['$elemMatch' => $hashId]];
+        $expected = ['complexRef.$id' => ['$elemMatch' => (object) $hashId]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$in' => array($hashId)));
-        $expected = array('complexRef.$id' => array('$in' => array((object) $hashId)));
+        $value = ['complexRef.id' => ['$in' => [$hashId]]];
+        $expected = ['complexRef.$id' => ['$in' => [(object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$not' => array('$elemMatch' => $hashId)));
-        $expected = array('complexRef.$id' => array('$not' => array('$elemMatch' => (object) $hashId)));
+        $value = ['complexRef.id' => ['$not' => ['$elemMatch' => $hashId]]];
+        $expected = ['complexRef.$id' => ['$not' => ['$elemMatch' => (object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('complexRef.id' => array('$not' => array('$in' => array($hashId))));
-        $expected = array('complexRef.$id' => array('$not' => array('$in' => array((object) $hashId))));
+        $value = ['complexRef.id' => ['$not' => ['$in' => [$hashId]]]];
+        $expected = ['complexRef.$id' => ['$not' => ['$in' => [(object) $hashId]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -340,35 +345,35 @@ public function testPrepareQueryOrNewObjWithEmbeddedReferenceToTargetDocumentWit
         $class = DocumentPersisterTestHashIdDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
 
-        $value = array('embeddedRef.id' => (string) $id);
-        $expected = array('embeddedRef.id' => $id);
+        $value = ['embeddedRef.id' => (string) $id];
+        $expected = ['embeddedRef.id' => $id];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$exists' => true));
-        $expected = array('embeddedRef.id' => array('$exists' => true));
+        $value = ['embeddedRef.id' => ['$exists' => true]];
+        $expected = ['embeddedRef.id' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$elemMatch' => (string) $id));
-        $expected = array('embeddedRef.id' => array('$elemMatch' => $id));
+        $value = ['embeddedRef.id' => ['$elemMatch' => (string) $id]];
+        $expected = ['embeddedRef.id' => ['$elemMatch' => $id]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$in' => array((string) $id)));
-        $expected = array('embeddedRef.id' => array('$in' => array($id)));
+        $value = ['embeddedRef.id' => ['$in' => [(string) $id]]];
+        $expected = ['embeddedRef.id' => ['$in' => [$id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$not' => array('$elemMatch' => (string) $id)));
-        $expected = array('embeddedRef.id' => array('$not' => array('$elemMatch' => $id)));
+        $value = ['embeddedRef.id' => ['$not' => ['$elemMatch' => (string) $id]]];
+        $expected = ['embeddedRef.id' => ['$not' => ['$elemMatch' => $id]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$not' => array('$in' => array((string) $id))));
-        $expected = array('embeddedRef.id' => array('$not' => array('$in' => array($id))));
+        $value = ['embeddedRef.id' => ['$not' => ['$in' => [(string) $id]]]];
+        $expected = ['embeddedRef.id' => ['$not' => ['$in' => [$id]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -381,33 +386,33 @@ public function testPrepareQueryOrNewObjWithEmbeddedReferenceToTargetDocumentWit
         $class = DocumentPersisterTestDocument::class;
         $documentPersister = $this->uow->getDocumentPersister($class);
 
-        $value = array('embeddedRef.id' => $hashId);
-        $expected = array('embeddedRef.id' => (object) $hashId);
+        $value = ['embeddedRef.id' => $hashId];
+        $expected = ['embeddedRef.id' => (object) $hashId];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$exists' => true));
-        $expected = array('embeddedRef.id' => array('$exists' => true));
+        $value = ['embeddedRef.id' => ['$exists' => true]];
+        $expected = ['embeddedRef.id' => ['$exists' => true]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$elemMatch' => $hashId));
-        $expected = array('embeddedRef.id' => array('$elemMatch' => (object) $hashId));
+        $value = ['embeddedRef.id' => ['$elemMatch' => $hashId]];
+        $expected = ['embeddedRef.id' => ['$elemMatch' => (object) $hashId]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$in' => array($hashId)));
-        $expected = array('embeddedRef.id' => array('$in' => array((object) $hashId)));
+        $value = ['embeddedRef.id' => ['$in' => [$hashId]]];
+        $expected = ['embeddedRef.id' => ['$in' => [(object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$not' => array('$elemMatch' => $hashId)));
-        $expected = array('embeddedRef.id' => array('$not' => array('$elemMatch' => (object) $hashId)));
+        $value = ['embeddedRef.id' => ['$not' => ['$elemMatch' => $hashId]]];
+        $expected = ['embeddedRef.id' => ['$not' => ['$elemMatch' => (object) $hashId]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
 
-        $value = array('embeddedRef.id' => array('$not' => array('$in' => array($hashId))));
-        $expected = array('embeddedRef.id' => array('$not' => array('$in' => array((object) $hashId))));
+        $value = ['embeddedRef.id' => ['$not' => ['$in' => [$hashId]]]];
+        $expected = ['embeddedRef.id' => ['$not' => ['$in' => [(object) $hashId]]]];
 
         $this->assertEquals($expected, $documentPersister->prepareQueryOrNewObj($value));
     }
@@ -417,24 +422,24 @@ public function testPrepareQueryOrNewObjWithEmbeddedReferenceToTargetDocumentWit
      */
     public static function dataProviderTestWriteConcern()
     {
-        return array(
-            'default' => array(
+        return [
+            'default' => [
                 'className' => DocumentPersisterTestDocument::class,
                 'writeConcern' => 1,
-            ),
-            'acknowledged' => array(
+            ],
+            'acknowledged' => [
                 'className' => DocumentPersisterWriteConcernAcknowledged::class,
                 'writeConcern' => 1,
-            ),
-            'unacknowledged' => array(
+            ],
+            'unacknowledged' => [
                 'className' => DocumentPersisterWriteConcernUnacknowledged::class,
                 'writeConcern' => 0,
-            ),
-            'majority' => array(
+            ],
+            'majority' => [
                 'className' => DocumentPersisterWriteConcernMajority::class,
                 'writeConcern' => 'majority',
-            ),
-        );
+            ],
+        ];
     }
 
     /**
@@ -481,7 +486,7 @@ public function testExecuteUpsertsRespectsWriteConcern($class, $writeConcern)
         $reflectionProperty->setValue($documentPersister, $collection);
 
         $testDocument = new $class();
-        $testDocument->id = new \MongoDB\BSON\ObjectId();
+        $testDocument->id = new ObjectId();
         $this->dm->persist($testDocument);
         $this->dm->flush();
     }
@@ -521,13 +526,13 @@ public function testDefaultWriteConcernIsRespected()
         $collection = $this->createMock(Collection::class);
         $collection->expects($this->once())
             ->method('insertMany')
-            ->with($this->isType('array'), $this->equalTo(array('w' => 0)));
+            ->with($this->isType('array'), $this->equalTo(['w' => 0]));
 
         $reflectionProperty = new \ReflectionProperty($documentPersister, 'collection');
         $reflectionProperty->setAccessible(true);
         $reflectionProperty->setValue($documentPersister, $collection);
 
-        $this->dm->getConfiguration()->setDefaultCommitOptions(array('w' => 0));
+        $this->dm->getConfiguration()->setDefaultCommitOptions(['w' => 0]);
 
         $testDocument = new $class();
         $this->dm->persist($testDocument);
@@ -544,7 +549,7 @@ public function testVersionIncrementOnUpdateSuccess()
         $collection = $this->createMock(Collection::class);
         $collection->expects($this->any())
             ->method('updateOne')
-            ->will($this->returnValue(array('n' => 1)));
+            ->will($this->returnValue(['n' => 1]));
 
         $reflectionProperty = new \ReflectionProperty($documentPersister, 'collection');
         $reflectionProperty->setAccessible(true);
@@ -552,7 +557,7 @@ public function testVersionIncrementOnUpdateSuccess()
 
         $testDocument = new $class();
         $testDocument->id = 12345;
-        $this->uow->registerManaged($testDocument, 12345, array('id' => 12345));
+        $this->uow->registerManaged($testDocument, 12345, ['id' => 12345]);
         $testDocument->name = 'test';
         $this->dm->persist($testDocument);
         $this->dm->flush();
@@ -570,7 +575,7 @@ public function testNoVersionIncrementOnUpdateFailure()
         $collection = $this->createMock(Collection::class);
         $collection->expects($this->any())
             ->method('updateOne')
-            ->will($this->returnValue(array('n' => 0)));
+            ->will($this->returnValue(['n' => 0]));
 
         $reflectionProperty = new \ReflectionProperty($documentPersister, 'collection');
         $reflectionProperty->setAccessible(true);
@@ -578,8 +583,8 @@ public function testNoVersionIncrementOnUpdateFailure()
 
         $testDocument = new $class();
         $testDocument->id = 12345;
-        $this->uow->registerManaged($testDocument, 12345, array('id' => 12345));
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->uow->registerManaged($testDocument, 12345, ['id' => 12345]);
+        $this->expectException(LockException::class);
         $testDocument->name = 'test';
         $this->dm->persist($testDocument);
         $this->dm->flush();
@@ -634,7 +639,6 @@ class DocumentPersisterTestDocumentWithVersion
 
     /** @ODM\Version @ODM\Field(type="int") */
     public $revision = 1;
-
 }
 
 /**
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
index 0460170e15..6557700255 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
@@ -1,20 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Ecommerce\ConfigurableProduct;
-use Documents\Ecommerce\StockItem;
 use Documents\Ecommerce\Currency;
 use Documents\Ecommerce\Money;
 use Documents\Ecommerce\Option;
+use Documents\Ecommerce\StockItem;
 
-class EcommerceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class EcommerceTest extends BaseTest
 {
     public function setUp()
     {
         parent::setUp();
 
-        $currencies = array('USD' => 1, 'EURO' => 1.7, 'JPN' => 0.0125);
+        $currencies = ['USD' => 1, 'EURO' => 1.7, 'JPN' => 0.0125];
 
         foreach ($currencies as $name => &$multiplier) {
             $multiplier = new Currency($name, $multiplier);
@@ -45,11 +48,11 @@ public function testEmbedding()
         $this->assertCount(3, $product->getOptions());
         $this->assertEquals(12.99, $product->getOption('small')->getPrice());
 
-        $usdCurrency = $this->dm->getRepository('Documents\Ecommerce\Currency')->findOneBy(array('name' => 'USD'));
+        $usdCurrency = $this->dm->getRepository('Documents\Ecommerce\Currency')->findOneBy(['name' => 'USD']);
         $this->assertNotNull($usdCurrency);
         $usdCurrency->setMultiplier('2');
 
-        $this->assertInstanceOf(\Documents\Ecommerce\StockItem::class, $product->getOption('small')->getStockItem());
+        $this->assertInstanceOf(StockItem::class, $product->getOption('small')->getStockItem());
         $this->assertNotNull($product->getOption('small')->getStockItem()->getId());
         $this->assertEquals(12.99 * 2, $product->getOption('small')->getPrice());
     }
@@ -61,7 +64,7 @@ public function testMoneyDocumentsAvailableForReference()
         $currency = $price->getCurrency();
         $this->assertInstanceOf(Currency::class, $currency);
         $this->assertNotNull($currency->getId());
-        $this->assertEquals($currency, $this->dm->getRepository('Documents\Ecommerce\Currency')->findOneBy(array('name' => Currency::USD)));
+        $this->assertEquals($currency, $this->dm->getRepository('Documents\Ecommerce\Currency')->findOneBy(['name' => Currency::USD]));
     }
 
     public function testRemoveOption()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedIdTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedIdTest.php
index 826541d775..7b9ef0b5fa 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedIdTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedIdTest.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 
-class EmbeddedIdTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class EmbeddedIdTest extends BaseTest
 {
     public function testEmbeddedIdsAreGenerated()
     {
@@ -17,7 +21,7 @@ public function testEmbeddedIdsAreGenerated()
 
     public function testEmbeddedIdsAreNotOverwritten()
     {
-        $id = (string) new \MongoDB\BSON\ObjectId();
+        $id = (string) new ObjectId();
         $test = new DefaultIdEmbeddedDocument();
         $test->id = $id;
 
@@ -61,7 +65,7 @@ class EmbeddedIdTestUser
     public $embedOne;
 
     /** @ODM\EmbedMany(targetDocument="DefaultIdEmbeddedDocument") */
-    public $embedMany = array();
+    public $embedMany = [];
 }
 
 /** @ODM\Document */
@@ -74,7 +78,7 @@ class EmbeddedStrategyNoneIdTestUser
     public $embedOne;
 
     /** @ODM\EmbedMany(targetDocument="DefaultIdStrategyNoneEmbeddedDocument") */
-    public $embedMany = array();
+    public $embedMany = [];
 }
 
 /** @ODM\EmbeddedDocument */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedReferenceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedReferenceTest.php
index 8030298430..2fbdc0754b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedReferenceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedReferenceTest.php
@@ -1,12 +1,14 @@
 <?php
 
-namespace Doctrine\ODM\MongoDB\Tests\Functional;
+declare(strict_types=1);
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class EmbeddedReferenceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class EmbeddedReferenceTest extends BaseTest
 {
     public function testReferencedDocumentInsideEmbeddedDocument()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedTest.php
index b2632095cf..fe74b8e452 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedTest.php
@@ -1,12 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Address;
-use Documents\Phonenumber;
-use Documents\Account;
-use Documents\User;
 use Documents\Functional\EmbeddedTestLevel0;
 use Documents\Functional\EmbeddedTestLevel0b;
 use Documents\Functional\EmbeddedTestLevel1;
@@ -15,14 +16,17 @@
 use Documents\Functional\NotSavedEmbedded;
 use Documents\Functional\VirtualHost;
 use Documents\Functional\VirtualHostDirective;
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Documents\Phonenumber;
+use Documents\User;
+use MongoDB\BSON\ObjectId;
+use function get_class;
 
-class EmbeddedTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class EmbeddedTest extends BaseTest
 {
     public function testSetEmbeddedToNull()
     {
         $user = new User();
-        $user->setId((string) new \MongoDB\BSON\ObjectId());
+        $user->setId((string) new ObjectId());
         $user->setUsername('jwage');
         $user->setAddress(null);
 
@@ -45,7 +49,7 @@ public function testFlushEmbedded()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(array('name' => 'test'));
+        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(['name' => 'test']);
         $this->assertInstanceOf('Documents\Functional\EmbeddedTestLevel0', $test);
 
         // Adding this flush here makes level1 not to be inserted.
@@ -148,7 +152,7 @@ public function testRemoveOneEmbedded()
 
     public function testManyEmbedded()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->addPhonenumber(new Phonenumber('6155139185'));
         $user->addPhonenumber(new Phonenumber('6153303769'));
 
@@ -423,11 +427,11 @@ public function testRemoveAddDeepEmbedded()
         $vhost->getVHostDirective()->addDirective($directive1);
 
         $directive2 = new VirtualHostDirective('Directory', '/var/www/html');
-        $directive2->addDirective(new VirtualHostDirective('AllowOverride','All'));
+        $directive2->addDirective(new VirtualHostDirective('AllowOverride', 'All'));
         $vhost->getVHostDirective()->addDirective($directive2);
 
         $directive3 = new VirtualHostDirective('Directory', '/var/www/html');
-        $directive3->addDirective(new VirtualHostDirective('RewriteEngine','on'));
+        $directive3->addDirective(new VirtualHostDirective('RewriteEngine', 'on'));
         $vhost->getVHostDirective()->addDirective($directive3);
 
         $this->dm->persist($vhost);
@@ -436,17 +440,15 @@ public function testRemoveAddDeepEmbedded()
         $vhost->getVHostDirective()->removeDirective($directive2);
 
         $directive4 = new VirtualHostDirective('Directory', '/var/www/html');
-        $directive4->addDirective(new VirtualHostDirective('RewriteEngine','on'));
+        $directive4->addDirective(new VirtualHostDirective('RewriteEngine', 'on'));
         $vhost->getVHostDirective()->addDirective($directive4);
 
-
         $this->dm->flush();
         $this->dm->clear();
 
         $vhost = $this->dm->find('Documents\Functional\VirtualHost', $vhost->getId());
 
-        foreach($vhost->getVHostDirective()->getDirectives() as $directive)
-        {
+        foreach ($vhost->getVHostDirective()->getDirectives() as $directive) {
             $this->assertNotEmpty($directive->getName());
         }
     }
@@ -470,7 +472,7 @@ public function testEmbeddedDocumentNotSavedFields()
 
     public function testChangeEmbedOneDocumentId()
     {
-        $originalId = (string) new \MongoDB\BSON\ObjectId();
+        $originalId = (string) new ObjectId();
 
         $test = new ChangeEmbeddedIdTest();
         $test->embed = new EmbeddedDocumentWithId();
@@ -479,7 +481,7 @@ public function testChangeEmbedOneDocumentId()
 
         $this->dm->flush();
 
-        $newId = (string) new \MongoDB\BSON\ObjectId();
+        $newId = (string) new ObjectId();
 
         $test->embed->id = $newId;
 
@@ -493,7 +495,7 @@ public function testChangeEmbedOneDocumentId()
 
     public function testChangeEmbedManyDocumentId()
     {
-        $originalId = (string) new \MongoDB\BSON\ObjectId();
+        $originalId = (string) new ObjectId();
 
         $test = new ChangeEmbeddedIdTest();
         $test->embedMany[] = new EmbeddedDocumentWithId();
@@ -502,7 +504,7 @@ public function testChangeEmbedManyDocumentId()
 
         $this->dm->flush();
 
-        $newId = (string) new \MongoDB\BSON\ObjectId();
+        $newId = (string) new ObjectId();
 
         $test->embedMany[0]->id = $newId;
 
@@ -516,7 +518,7 @@ public function testChangeEmbedManyDocumentId()
 
     public function testEmbeddedDocumentsWithSameIdAreNotSameInstance()
     {
-        $originalId = (string) new \MongoDB\BSON\ObjectId();
+        $originalId = (string) new ObjectId();
 
         $test = new ChangeEmbeddedIdTest();
         $test->embed = new EmbeddedDocumentWithId();
@@ -538,8 +540,8 @@ public function testWhenCopyingManyEmbedSubDocumentsFromOneDocumentToAnotherWill
         $test1 = new ChangeEmbeddedIdTest();
 
         $embedded = new EmbeddedDocumentWithId();
-        $embedded->id = (string) new \MongoDB\BSON\ObjectId();
-        $test1->embedMany = array($embedded);
+        $embedded->id = (string) new ObjectId();
+        $test1->embedMany = [$embedded];
 
         $this->dm->persist($test1);
         $this->dm->flush();
@@ -552,7 +554,6 @@ public function testWhenCopyingManyEmbedSubDocumentsFromOneDocumentToAnotherWill
 
         $this->dm->flush();
 
-
         //do some operations on test1
         $this->dm->persist($test1);
         $this->dm->flush();
@@ -569,7 +570,7 @@ public function testReusedEmbeddedDocumentsAreClonedInFact()
         $test2 = new ChangeEmbeddedIdTest();
 
         $embedded = new EmbeddedDocumentWithId();
-        $embedded->id = (string) new \MongoDB\BSON\ObjectId();
+        $embedded->id = (string) new ObjectId();
 
         $test1->embed = $embedded;
         $test2->embed = $embedded;
@@ -592,7 +593,7 @@ public function testEmbeddedDocumentWithDifferentFieldNameAnnotation()
         $test1 = new ChangeEmbeddedWithNameAnnotationTest();
 
         $embedded = new EmbeddedDocumentWithId();
-        $embedded->id = (string) new \MongoDB\BSON\ObjectId();
+        $embedded->id = (string) new ObjectId();
 
         $firstEmbedded = new EmbedDocumentWithAnotherEmbed();
         $firstEmbedded->embed = $embedded;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EnsureShardingTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EnsureShardingTest.php
index 60905414fa..71ca8db8e4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EnsureShardingTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EnsureShardingTest.php
@@ -1,9 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Sharded\ShardedOne;
+use Documents\Sharded\ShardedOneWithDifferentKey;
+use function iterator_to_array;
 
 class EnsureShardingTest extends BaseTest
 {
@@ -11,73 +15,73 @@ public function setUp()
     {
         parent::setUp();
 
-        $this->skipTestIfNotSharded(\Documents\Sharded\ShardedOne::class);
+        $this->skipTestIfNotSharded(ShardedOne::class);
     }
 
     public function testEnsureShardingForNewCollection()
     {
-        $class = \Documents\Sharded\ShardedOne::class;
+        $class = ShardedOne::class;
         $this->dm->getSchemaManager()->ensureDocumentSharding($class);
 
         $collection = $this->dm->getDocumentCollection($class);
         $indexes = iterator_to_array($collection->listIndexes());
-        $stats = $this->dm->getDocumentDatabase($class)->command(array('collstats' => $collection->getCollectionName()))->toArray()[0];
+        $stats = $this->dm->getDocumentDatabase($class)->command(['collstats' => $collection->getCollectionName()])->toArray()[0];
 
         $this->assertCount(2, $indexes);
-        $this->assertSame(array('k' => 1), $indexes[1]['key']);
+        $this->assertSame(['k' => 1], $indexes[1]['key']);
         $this->assertTrue($stats['sharded']);
     }
 
     public function testEnsureShardingForCollectionWithDocuments()
     {
         $this->markTestSkipped('Test does not pass due to https://github.com/mongodb/mongo-php-driver/issues/296');
-        $class = \Documents\Sharded\ShardedOne::class;
+        $class = ShardedOne::class;
         $collection = $this->dm->getDocumentCollection($class);
-        $doc = array('title' => 'hey', 'k' => 'hi');
+        $doc = ['title' => 'hey', 'k' => 'hi'];
         $collection->insertOne($doc);
 
         $this->dm->getSchemaManager()->ensureDocumentSharding($class);
 
         $indexes = iterator_to_array($collection->listIndexes());
-        $stats = $this->dm->getDocumentDatabase($class)->command(array('collstats' => $collection->getCollectionName()))->toArray()[0];
+        $stats = $this->dm->getDocumentDatabase($class)->command(['collstats' => $collection->getCollectionName()])->toArray()[0];
 
         $this->assertCount(2, $indexes);
-        $this->assertSame(array('k' => 1), $indexes[1]['key']);
+        $this->assertSame(['k' => 1], $indexes[1]['key']);
         $this->assertTrue($stats['sharded']);
     }
 
     public function testEnsureShardingForCollectionWithShardingEnabled()
     {
-        $class = \Documents\Sharded\ShardedOneWithDifferentKey::class;
+        $class = ShardedOneWithDifferentKey::class;
         $this->dm->getSchemaManager()->ensureDocumentSharding($class);
 
-        $this->dm->getSchemaManager()->ensureDocumentSharding(\Documents\Sharded\ShardedOne::class);
+        $this->dm->getSchemaManager()->ensureDocumentSharding(ShardedOne::class);
 
         $collection = $this->dm->getDocumentCollection($class);
         $indexes = iterator_to_array($collection->listIndexes());
-        $stats = $this->dm->getDocumentDatabase($class)->command(array('collstats' => $collection->getCollectionName()))->toArray()[0];
+        $stats = $this->dm->getDocumentDatabase($class)->command(['collstats' => $collection->getCollectionName()])->toArray()[0];
 
         $this->assertCount(2, $indexes);
-        $this->assertSame(array('v' => 1), $indexes[1]['key']);
+        $this->assertSame(['v' => 1], $indexes[1]['key']);
         $this->assertTrue($stats['sharded']);
     }
 
     public function testEnsureShardingForCollectionWithData()
     {
         $this->markTestSkipped('Test does not pass due to https://github.com/mongodb/mongo-php-driver/issues/296');
-        $document = new \Documents\Sharded\ShardedOne();
+        $document = new ShardedOne();
         $this->dm->persist($document);
         $this->dm->flush();
 
-        $class = \Documents\Sharded\ShardedOne::class;
+        $class = ShardedOne::class;
         $this->dm->getSchemaManager()->ensureDocumentSharding($class);
 
         $collection = $this->dm->getDocumentCollection($class);
         $indexes = iterator_to_array($collection->listIndexes());
-        $stats = $this->dm->getDocumentDatabase($class)->command(array('collstats' => $collection->getCollectionName()))->toArray()[0];
+        $stats = $this->dm->getDocumentDatabase($class)->command(['collstats' => $collection->getCollectionName()])->toArray()[0];
 
         $this->assertCount(2, $indexes);
-        $this->assertSame(array('k' => 1), $indexes[1]['key']);
+        $this->assertSame(['k' => 1], $indexes[1]['key']);
         $this->assertTrue($stats['sharded']);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
index c371923125..568ed60a98 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
@@ -1,18 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\User;
+use Doctrine\ODM\MongoDB\DocumentNotFoundException;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Group;
 use Documents\Profile;
+use Documents\User;
+use function sort;
 
-class FilterTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class FilterTest extends BaseTest
 {
     public function setUp()
     {
         parent::setUp();
 
-        $this->ids = array();
+        $this->ids = [];
 
         $groupA = new Group('groupA');
         $groupB = new Group('groupB');
@@ -71,15 +76,15 @@ protected function enableProfileFilter()
 
     public function testRepositoryFind()
     {
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFind());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFind());
 
         $this->enableUserFilter();
         $this->dm->clear();
-        $this->assertEquals(array('Tim'), $this->getUsernamesWithFind());
+        $this->assertEquals(['Tim'], $this->getUsernamesWithFind());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFind());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFind());
     }
 
     protected function getUsernamesWithFind()
@@ -89,12 +94,12 @@ protected function getUsernamesWithFind()
         $tim = $repository->find($this->ids['tim']);
         $john = $repository->find($this->ids['john']);
 
-        $usernames = array();
+        $usernames = [];
 
-        if(isset($tim)) {
+        if (isset($tim)) {
             $usernames[] = $tim->getUsername();
         }
-        if(isset($john)) {
+        if (isset($john)) {
             $usernames[] = $john->getUsername();
         }
 
@@ -104,22 +109,22 @@ protected function getUsernamesWithFind()
 
     public function testRepositoryFindBy()
     {
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFindBy());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFindBy());
 
         $this->enableUserFilter();
         $this->dm->clear();
-        $this->assertEquals(array('Tim'), $this->getUsernamesWithFindBy());
+        $this->assertEquals(['Tim'], $this->getUsernamesWithFindBy());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFindBy());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFindBy());
     }
 
     protected function getUsernamesWithFindBy()
     {
-        $all = $this->dm->getRepository('Documents\User')->findBy(array('hits' => 10));
+        $all = $this->dm->getRepository('Documents\User')->findBy(['hits' => 10]);
 
-        $usernames = array();
+        $usernames = [];
         foreach ($all as $user) {
             $usernames[] = $user->getUsername();
         }
@@ -142,29 +147,29 @@ public function testRepositoryFindOneBy()
 
     protected function getJohnsUsernameWithFindOneBy()
     {
-        $john = $this->dm->getRepository('Documents\User')->findOneBy(array('id' => $this->ids['john']));
+        $john = $this->dm->getRepository('Documents\User')->findOneBy(['id' => $this->ids['john']]);
 
         return isset($john) ? $john->getUsername() : null;
     }
 
     public function testRepositoryFindAll()
     {
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFindAll());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFindAll());
 
         $this->enableUserFilter();
         $this->dm->clear();
-        $this->assertEquals(array('Tim'), $this->getUsernamesWithFindAll());
+        $this->assertEquals(['Tim'], $this->getUsernamesWithFindAll());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithFindAll());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithFindAll());
     }
 
     protected function getUsernamesWithFindAll()
     {
         $all = $this->dm->getRepository('Documents\User')->findAll();
 
-        $usernames = array();
+        $usernames = [];
         foreach ($all as $user) {
             $usernames[] = $user->getUsername();
         }
@@ -174,26 +179,26 @@ protected function getUsernamesWithFindAll()
 
     public function testReferenceMany()
     {
-        $this->assertEquals(array('groupA', 'groupB'), $this->getGroupsByReference());
+        $this->assertEquals(['groupA', 'groupB'], $this->getGroupsByReference());
 
         $this->enableGroupFilter();
         $this->dm->clear();
-        $this->assertEquals(array('groupA'), $this->getGroupsByReference());
+        $this->assertEquals(['groupA'], $this->getGroupsByReference());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('groupA', 'groupB'), $this->getGroupsByReference());
+        $this->assertEquals(['groupA', 'groupB'], $this->getGroupsByReference());
     }
 
     protected function getGroupsByReference()
     {
         $tim = $this->dm->getRepository('Documents\User')->find($this->ids['tim']);
 
-        $groupnames = array();
+        $groupnames = [];
         foreach ($tim->getGroups() as $group) {
             try {
                 $groupnames[] = $group->getName();
-            } catch (\Doctrine\ODM\MongoDB\DocumentNotFoundException $e) {
+            } catch (DocumentNotFoundException $e) {
                //Proxy object filtered
             }
         }
@@ -221,7 +226,7 @@ protected function getProfileByReference()
         $profile = $tim->getProfile();
         try {
             return $profile->getFirstname();
-        } catch (\Doctrine\ODM\MongoDB\DocumentNotFoundException $e) {
+        } catch (DocumentNotFoundException $e) {
             //Proxy object filtered
             return null;
         }
@@ -229,15 +234,15 @@ protected function getProfileByReference()
 
     public function testDocumentManagerRef()
     {
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithDocumentManager());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithDocumentManager());
 
         $this->enableUserFilter();
         $this->dm->clear();
-        $this->assertEquals(array('Tim'), $this->getUsernamesWithDocumentManager());
+        $this->assertEquals(['Tim'], $this->getUsernamesWithDocumentManager());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithDocumentManager());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithDocumentManager());
     }
 
     protected function getUsernamesWithDocumentManager()
@@ -245,17 +250,17 @@ protected function getUsernamesWithDocumentManager()
         $tim = $this->dm->getReference('Documents\User', $this->ids['tim']);
         $john = $this->dm->getReference('Documents\User', $this->ids['john']);
 
-        $usernames = array();
+        $usernames = [];
 
         try {
             $usernames[] = $tim->getUsername();
-        } catch (\Doctrine\ODM\MongoDB\DocumentNotFoundException $e) {
+        } catch (DocumentNotFoundException $e) {
             //Proxy object filtered
         }
 
         try {
             $usernames[] = $john->getUsername();
-        } catch (\Doctrine\ODM\MongoDB\DocumentNotFoundException $e) {
+        } catch (DocumentNotFoundException $e) {
             //Proxy object filtered
         }
 
@@ -265,15 +270,15 @@ protected function getUsernamesWithDocumentManager()
 
     public function testQuery()
     {
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithQuery());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithQuery());
 
         $this->enableUserFilter();
         $this->dm->clear();
-        $this->assertEquals(array('Tim'), $this->getUsernamesWithQuery());
+        $this->assertEquals(['Tim'], $this->getUsernamesWithQuery());
 
         $this->fc->disable('testFilter');
         $this->dm->clear();
-        $this->assertEquals(array('John', 'Tim'), $this->getUsernamesWithQuery());
+        $this->assertEquals(['John', 'Tim'], $this->getUsernamesWithQuery());
     }
 
     protected function getUsernamesWithQuery()
@@ -282,7 +287,7 @@ protected function getUsernamesWithQuery()
         $query = $qb->getQuery();
         $all = $query->execute();
 
-        $usernames = array();
+        $usernames = [];
         foreach ($all as $user) {
             $usernames[] = $user->getUsername();
         }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FindAndModifyTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FindAndModifyTest.php
index a8aa7388b2..cfa99daa89 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FindAndModifyTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FindAndModifyTest.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
 
-class FindAndModifyTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class FindAndModifyTest extends BaseTest
 {
     public function testFindAndModify()
     {
         $coll = $this->dm->getDocumentCollection('Documents\User');
-        $docs = array(array('count' => 0), array('count' => 0));
+        $docs = [['count' => 0], ['count' => 0]];
         $coll->insertMany($docs);
 
         // test update findAndModify
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FlushTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FlushTest.php
index f6be0a1e70..ff86e4dcca 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FlushTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FlushTest.php
@@ -1,12 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\CmsAddress;
-use Documents\CmsUser;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\FriendUser;
+use function get_class;
 
-class FlushTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class FlushTest extends BaseTest
 {
     /**
      * Given 3 users, userA userB userC
@@ -29,7 +31,9 @@ public function testFlush()
         $userB->addFriend($userC);
 
         // persist all users, flush and clear
-        foreach (array($userA, $userB, $userC) as $user) $this->dm->persist($user);
+        foreach ([$userA, $userB, $userC] as $user) {
+            $this->dm->persist($user);
+        }
         $this->dm->flush();
         $this->dm->clear();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FunctionalTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FunctionalTest.php
index 0fb20513fb..c1835ed461 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FunctionalTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FunctionalTest.php
@@ -1,18 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\PersistentCollection;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Account;
+use Documents\Address;
+use Documents\Agent;
+use Documents\Album;
 use Documents\Bars\Bar;
 use Documents\Bars\Location;
-use Documents\User;
-use Documents\Account;
-use Documents\Phonenumber;
+use Documents\Category;
 use Documents\Employee;
-use Documents\Manager;
-use Documents\Address;
-use Documents\Group;
-use Documents\Project;
 use Documents\Functional\EmbeddedTestLevel0;
 use Documents\Functional\EmbeddedTestLevel0b;
 use Documents\Functional\EmbeddedTestLevel1;
@@ -27,20 +29,25 @@
 use Documents\Functional\SameCollection1;
 use Documents\Functional\SameCollection2;
 use Documents\Functional\SameCollection3;
-use Documents\Album;
+use Documents\Group;
+use Documents\GuestServer;
+use Documents\Manager;
+use Documents\Phonenumber;
+use Documents\Project;
 use Documents\Song;
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Documents\SubCategory;
+use Documents\User;
 use MongoDB\BSON\ObjectId;
 
-class FunctionalTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class FunctionalTest extends BaseTest
 {
     public function provideUpsertObjects()
     {
-        return array(
-            array('Documents\\UserUpsert', new \MongoDB\BSON\ObjectId('4f18f593acee41d724000005'), 'user'),
-            array('Documents\\UserUpsertIdStrategyNone', 'jwage', 'user'),
-            array('Documents\\UserUpsertChild', new \MongoDB\BSON\ObjectId('4f18f593acee41d724000005'), 'child')
-        );
+        return [
+            ['Documents\\UserUpsert', new ObjectId('4f18f593acee41d724000005'), 'user'],
+            ['Documents\\UserUpsertIdStrategyNone', 'jwage', 'user'],
+            ['Documents\\UserUpsertChild', new ObjectId('4f18f593acee41d724000005'), 'child'],
+        ];
     }
 
     /**
@@ -52,30 +59,30 @@ public function testUpsertObject($className, $id, $discriminator)
         $user->id = (string) $id;
         $user->username = 'test';
         $user->count = 1;
-        $group = new \Documents\Group('Group');
-        $user->groups = array($group);
+        $group = new Group('Group');
+        $user->groups = [$group];
         $this->dm->persist($user);
         $this->dm->flush();
         $this->dm->clear();
 
-        $check = $this->dm->getDocumentCollection($className)->findOne(array('_id' => $id));
+        $check = $this->dm->getDocumentCollection($className)->findOne(['_id' => $id]);
         $this->assertNotNull($check);
         $this->assertEquals((string) $id, (string) $check['_id']);
         $this->assertEquals($group->getId(), (string) $check['groups'][0]['$id']);
         $this->assertEquals($discriminator, $check['discriminator']);
 
-        $group2 = new \Documents\Group('Group');
+        $group2 = new Group('Group');
 
         $user = new $className();
         $user->id = $id;
         $user->hits = 5;
         $user->count = 2;
-        $user->groups = array($group2);
+        $user->groups = [$group2];
         $this->dm->persist($user);
         $this->dm->flush();
         $this->dm->clear();
 
-        $check = $this->dm->getDocumentCollection($className)->findOne(array('_id' => $id));
+        $check = $this->dm->getDocumentCollection($className)->findOne(['_id' => $id]);
         $this->assertEquals($discriminator, $check['discriminator']);
         $this->assertEquals(3, $check['count']);
         $this->assertEquals(5, $check['hits']);
@@ -91,7 +98,7 @@ public function testUpsertObject($className, $id, $discriminator)
         $this->dm->persist($user);
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection($className)->findOne(array('_id' => $id));
+        $check = $this->dm->getDocumentCollection($className)->findOne(['_id' => $id]);
         $this->assertEquals($discriminator, $check['discriminator']);
         $this->assertEquals(3, $check['count']);
         $this->assertEquals(100, $check['hits']);
@@ -110,9 +117,9 @@ public function testInheritedAssociationMappings()
 
     public function testNestedCategories()
     {
-        $root = new \Documents\Category('Root');
-        $child1 = new \Documents\SubCategory('Child 1');
-        $child2 = new \Documents\SubCategory('Child 2');
+        $root = new Category('Root');
+        $child1 = new SubCategory('Child 1');
+        $child2 = new SubCategory('Child 2');
         $child1->addChild($child2);
         $root->addChild($child1);
 
@@ -144,7 +151,7 @@ public function testManyEmbedded()
         $songs->add(new Song('Song #3'));
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(array('name' => 'Jon'));
+        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(['name' => 'Jon']);
         $this->assertEquals('Song #1 Changed', $test['songs'][0]['name']);
 
         $album->setName('jwage');
@@ -154,7 +161,7 @@ public function testManyEmbedded()
         unset($songs[0]);
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(array('name' => 'jwage'));
+        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(['name' => 'jwage']);
 
         $this->assertEquals('jwage', $test['name']);
         $this->assertEquals('ok', $test['songs'][0]['name']);
@@ -167,7 +174,7 @@ public function testManyEmbedded()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(array('name' => 'jwage'));
+        $test = $this->dm->getDocumentCollection('Documents\Album')->findOne(['name' => 'jwage']);
         $this->assertFalse(isset($test['songs']));
     }
 
@@ -189,7 +196,7 @@ public function testNewEmbedded()
         $subAddress->setCity('New Sub-City');
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection('Documents\Project')->findOne(array('name' => 'Project'));
+        $test = $this->dm->getDocumentCollection('Documents\Project')->findOne(['name' => 'Project']);
 
         $this->assertEquals('New Sub-City', $test['address']['subAddress']['city']);
         $this->assertEquals('New City', $test['address']['city']);
@@ -197,7 +204,7 @@ public function testNewEmbedded()
 
     public function testPersistingNewDocumentWithOnlyOneReference()
     {
-        $server = new \Documents\GuestServer();
+        $server = new GuestServer();
         $server->name = 'test';
         $this->dm->persist($server);
         $this->dm->flush();
@@ -207,7 +214,7 @@ public function testPersistingNewDocumentWithOnlyOneReference()
 
         $server = $this->dm->getReference('Documents\GuestServer', $id);
 
-        $agent = new \Documents\Agent();
+        $agent = new Agent();
         $agent->server = $server;
         $this->dm->persist($agent);
         $this->dm->flush();
@@ -222,32 +229,32 @@ public function testPersistingNewDocumentWithOnlyOneReference()
 
     public function testCollection()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('joncolltest');
-        $user->log(array('test'));
-        $user->log(array('test'));
+        $user->log(['test']);
+        $user->log(['test']);
         $this->dm->persist($user);
         $this->dm->flush();
         $this->dm->clear();
 
         $coll = $this->dm->getDocumentCollection('Documents\User');
-        $document = $coll->findOne(array('username' => 'joncolltest'));
+        $document = $coll->findOne(['username' => 'joncolltest']);
         $this->assertCount(2, $document['logs']);
 
-        $document = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'joncolltest'));
+        $document = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'joncolltest']);
         $this->assertCount(2, $document->getLogs());
-        $document->log(array('test'));
+        $document->log(['test']);
         $this->dm->flush();
         $this->dm->clear();
 
-        $document = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'joncolltest'));
+        $document = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'joncolltest']);
         $this->assertCount(3, $document->getLogs());
-        $document->setLogs(array('ok', 'test'));
+        $document->setLogs(['ok', 'test']);
         $this->dm->flush();
         $this->dm->clear();
 
-        $document = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'joncolltest'));
-        $this->assertEquals(array('ok', 'test'), $document->getLogs());
+        $document = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'joncolltest']);
+        $this->assertEquals(['ok', 'test'], $document->getLogs());
     }
 
     public function testSameObjectValuesInCollection()
@@ -260,7 +267,7 @@ public function testSameObjectValuesInCollection()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'testing'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'testing']);
         $this->assertCount(2, $user->getPhonenumbers());
     }
 
@@ -275,14 +282,14 @@ public function testIncrement()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
 
         $user->incrementCount(5);
         $user->incrementFloatCount(5);
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(105, $user->getCount());
         $this->assertSame(105.0, $user->getFloatCount());
 
@@ -291,7 +298,7 @@ public function testIncrement()
 
         $this->dm->flush();
         $this->dm->clear();
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(50, $user->getCount());
         $this->assertSame(50.0, $user->getFloatCount());
     }
@@ -307,14 +314,14 @@ public function testIncrementWithFloat()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
 
         $user->incrementCount(1.337);
         $user->incrementFloatCount(1.337);
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(101, $user->getCount());
         $this->assertSame(101.337, $user->getFloatCount());
 
@@ -323,7 +330,7 @@ public function testIncrementWithFloat()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(110, $user->getCount());
         $this->assertSame(110.5, $user->getFloatCount());
     }
@@ -339,7 +346,7 @@ public function testIncrementSetsNull()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(10, $user->getCount());
         $this->assertSame(10.0, $user->getFloatCount());
 
@@ -348,7 +355,7 @@ public function testIncrementSetsNull()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertSame(11, $user->getCount());
         $this->assertSame(11.0, $user->getFloatCount());
 
@@ -357,7 +364,7 @@ public function testIncrementSetsNull()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jon'));
+        $user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jon']);
         $this->assertNull($user->getCount());
         $this->assertNull($user->getFloatCount());
     }
@@ -475,11 +482,11 @@ public function testNotSavedFields()
     {
         $collection = $this->dm->getDocumentCollection('Documents\Functional\NotSaved');
         $collection->drop();
-        $test = array(
+        $test = [
             '_id' => new ObjectId(),
             'name' => 'Jonathan Wage',
             'notSaved' => 'test',
-        );
+        ];
         $collection->insertOne($test);
         $notSaved = $this->dm->find('Documents\Functional\NotSaved', $test['_id']);
         $this->assertEquals('Jonathan Wage', $notSaved->name);
@@ -492,7 +499,7 @@ public function testNotSavedFields()
         $this->dm->flush();
         $this->dm->clear();
 
-        $notSaved = $collection->findOne(array('name' => 'Roman Borschel'));
+        $notSaved = $collection->findOne(['name' => 'Roman Borschel']);
         $this->assertEquals('Roman Borschel', $notSaved['name']);
         $this->assertFalse(isset($notSaved['notSaved']));
     }
@@ -518,10 +525,10 @@ public function testTypeClassMissing()
         $this->dm->flush();
         $this->dm->clear();
 
-        /** @var $test FavoritesUser */
+        /** @var FavoritesUser $test */
         $test = $this->dm->find('Documents\Functional\FavoritesUser', $user->getId());
 
-        /** @var $collection PersistentCollection */
+        /** @var PersistentCollection $collection */
         $collection = $test->getFavorites();
         $collection->getTypeClass();
     }
@@ -536,10 +543,10 @@ public function testTypeClass()
         $this->dm->flush();
         $this->dm->clear();
 
-        /** @var $test Bar */
+        /** @var Bar $test */
         $test = $this->dm->find('Documents\Bars\Bar', $bar->getId());
 
-        /** @var $collection PersistentCollection */
+        /** @var PersistentCollection $collection */
         $collection = $test->getLocations();
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\Mapping\ClassMetadata', $collection->getTypeClass());
     }
@@ -576,14 +583,14 @@ public function testFavoritesReference()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getDocumentCollection('Documents\Functional\FavoritesUser')->findOne(array('name' => 'favorites'));
+        $test = $this->dm->getDocumentCollection('Documents\Functional\FavoritesUser')->findOne(['name' => 'favorites']);
         $this->assertTrue(isset($test['favorites'][0]['type']));
         $this->assertEquals('project', $test['favorites'][0]['type']);
         $this->assertEquals('group', $test['favorites'][1]['type']);
         $this->assertTrue(isset($test['favorite']['_doctrine_class_name']));
         $this->assertEquals('Documents\Project', $test['favorite']['_doctrine_class_name']);
 
-        $user = $this->dm->getRepository('Documents\Functional\FavoritesUser')->findOneBy(array('name' => 'favorites'));
+        $user = $this->dm->getRepository('Documents\Functional\FavoritesUser')->findOneBy(['name' => 'favorites']);
         $favorites = $user->getFavorites();
         $this->assertInstanceOf('Documents\Project', $favorites[0]);
         $this->assertInstanceOf('Documents\Group', $favorites[1]);
@@ -617,7 +624,7 @@ public function testPreUpdate()
         $this->dm->flush();
         $this->dm->clear();
 
-        $product = $this->dm->getRepository('Documents\Functional\PreUpdateTestProduct')->findOneBy(array('name' => 'Product'));
+        $product = $this->dm->getRepository('Documents\Functional\PreUpdateTestProduct')->findOneBy(['name' => 'Product']);
 
         $this->assertInstanceOf('Documents\Functional\PreUpdateTestSellable', $product->sellable);
         $this->assertInstanceOf('Documents\Functional\PreUpdateTestProduct', $product->sellable->getProduct());
@@ -631,14 +638,14 @@ public function testPreUpdate()
 
         $sellable = new PreUpdateTestSellable();
         $sellable->product = $product;
-        $sellable->seller = $this->dm->getRepository('Documents\Functional\PreUpdateTestSeller')->findOneBy(array('name' => 'Seller'));
+        $sellable->seller = $this->dm->getRepository('Documents\Functional\PreUpdateTestSeller')->findOneBy(['name' => 'Seller']);
 
         $product->sellable = $sellable;
 
         $this->dm->flush();
         $this->dm->clear();
 
-        $product = $this->dm->getRepository('Documents\Functional\PreUpdateTestProduct')->findOneBy(array('name' => 'Product2'));
+        $product = $this->dm->getRepository('Documents\Functional\PreUpdateTestProduct')->findOneBy(['name' => 'Product2']);
         $this->assertEquals('Seller', $product->sellable->getSeller()->getName());
         $this->assertEquals('Product2', $product->sellable->getProduct()->getName());
     }
@@ -659,25 +666,25 @@ public function testSameCollectionTest()
         $this->dm->persist($test3);
         $this->dm->flush();
 
-        $test = $this->dm->getRepository('Documents\Functional\SameCollection1')->findOneBy(array('name' => 'test1'));
+        $test = $this->dm->getRepository('Documents\Functional\SameCollection1')->findOneBy(['name' => 'test1']);
         $this->assertNotNull($test);
         $this->assertInstanceOf('Documents\Functional\SameCollection1', $test);
 
-        $test = $this->dm->getRepository('Documents\Functional\SameCollection2')->findOneBy(array('name' => 'test2'));
+        $test = $this->dm->getRepository('Documents\Functional\SameCollection2')->findOneBy(['name' => 'test2']);
         $this->assertNotNull($test);
         $this->assertInstanceOf('Documents\Functional\SameCollection2', $test);
 
-        $test = $this->dm->getRepository('Documents\Functional\SameCollection1')->findOneBy(array('name' => 'test3'));
+        $test = $this->dm->getRepository('Documents\Functional\SameCollection1')->findOneBy(['name' => 'test3']);
         $this->assertNotNull($test);
         $this->assertInstanceOf('Documents\Functional\SameCollection1', $test);
 
-        $test = $this->dm->getRepository('Documents\Functional\SameCollection2')->findOneBy(array('name' => 'test1'));
+        $test = $this->dm->getRepository('Documents\Functional\SameCollection2')->findOneBy(['name' => 'test1']);
         $this->assertNull($test);
 
-        $qb = $this->dm->createQueryBuilder(array(
+        $qb = $this->dm->createQueryBuilder([
             'Documents\Functional\SameCollection1',
-            'Documents\Functional\SameCollection2')
-        );
+            'Documents\Functional\SameCollection2',
+        ]);
         $q = $qb->getQuery();
         $test = $q->execute()->toArray();
         $this->assertCount(3, $test);
@@ -696,10 +703,10 @@ public function testSameCollectionTest()
      */
     public function testNotSameCollectionThrowsException()
     {
-        $test = $this->dm->createQueryBuilder(array(
+        $test = $this->dm->createQueryBuilder([
              'Documents\User',
-             'Documents\Profile')
-         )->getQuery()->execute();
+             'Documents\Profile',
+        ])->getQuery()->execute();
     }
 
     public function testEmbeddedNesting()
@@ -842,7 +849,7 @@ public function testReplaceEntireGroupsArray()
         //$user->getGroups()->clear();
         //$user->getGroups()->add($group2);
 
-        $user->setGroups(array($group2));
+        $user->setGroups([$group2]);
 
         $this->assertCount(1, $user->getGroups());
 
@@ -896,7 +903,7 @@ class ParentAssociationTestB
     /** @ODM\Field(type="string") */
     public $name;
     /** @ODM\EmbedMany */
-    public $children = array();
+    public $children = [];
     public function __construct($name)
     {
         $this->name = $name;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/HasLifecycleCallbacksTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/HasLifecycleCallbacksTest.php
index ece7dde069..cad6cc424b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/HasLifecycleCallbacksTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/HasLifecycleCallbacksTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class HasLifecycleCallbacksTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class HasLifecycleCallbacksTest extends BaseTest
 {
     public function testHasLifecycleCallbacksSubExtendsSuper()
     {
@@ -110,7 +113,7 @@ abstract class HasLifecycleCallbacksSuper
     /** @ODM\Id */
     public $id;
 
-    public $invoked = array();
+    public $invoked = [];
 
     /** @ODM\PrePersist */
     public function prePersist()
@@ -125,7 +128,7 @@ abstract class HasLifecycleCallbacksSuperAnnotated
     /** @ODM\Id */
     public $id;
 
-    public $invoked = array();
+    public $invoked = [];
 
     /** @ODM\PrePersist */
     public function prePersist()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdTest.php
index 2cd388019c..313819917f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdTest.php
@@ -1,10 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-
-class IdTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\UTCDateTime;
+use function class_exists;
+use function date;
+use function get_class;
+use function gettype;
+use function is_object;
+use function md5;
+use function serialize;
+use function sprintf;
+use function ucfirst;
+use function unserialize;
+
+class IdTest extends BaseTest
 {
     public function testUuidId()
     {
@@ -14,15 +31,15 @@ public function testUuidId()
         $id = $user->id;
 
         $this->dm->clear();
-        $check1 = $this->dm->getRepository(__NAMESPACE__.'\UuidUser')->findOneBy(array('id' => $id));
+        $check1 = $this->dm->getRepository(__NAMESPACE__ . '\UuidUser')->findOneBy(['id' => $id]);
         $this->assertNotNull($check1);
 
-        $check2 = $this->dm->createQueryBuilder(__NAMESPACE__.'\UuidUser')
+        $check2 = $this->dm->createQueryBuilder(__NAMESPACE__ . '\UuidUser')
             ->field('id')->equals($id)->getQuery()->getSingleResult();
         $this->assertNotNull($check2);
         $this->assertSame($check1, $check2);
 
-        $check3 = $this->dm->createQueryBuilder(__NAMESPACE__.'\UuidUser')
+        $check3 = $this->dm->createQueryBuilder(__NAMESPACE__ . '\UuidUser')
             ->field('name')->equals('Jonathan H. Wage')->getQuery()->getSingleResult();
         $this->assertNotNull($check3);
         $this->assertSame($check2, $check3);
@@ -37,15 +54,15 @@ public function testAlnumIdChars()
         $this->dm->flush();
 
         $this->dm->clear();
-        $check1 = $this->dm->getRepository(__NAMESPACE__.'\AlnumCharsUser')->findOneBy(array('id' => 'x'));
+        $check1 = $this->dm->getRepository(__NAMESPACE__ . '\AlnumCharsUser')->findOneBy(['id' => 'x']);
         $this->assertNotNull($check1);
 
-        $check2 = $this->dm->createQueryBuilder(__NAMESPACE__.'\AlnumCharsUser')
+        $check2 = $this->dm->createQueryBuilder(__NAMESPACE__ . '\AlnumCharsUser')
             ->field('id')->equals('x')->getQuery()->getSingleResult();
         $this->assertNotNull($check2);
         $this->assertSame($check1, $check2);
 
-        $check3 = $this->dm->createQueryBuilder(__NAMESPACE__.'\AlnumCharsUser')
+        $check3 = $this->dm->createQueryBuilder(__NAMESPACE__ . '\AlnumCharsUser')
             ->field('name')->equals('Kathrine R. Cage')->getQuery()->getSingleResult();
         $this->assertNotNull($check3);
         $this->assertSame($check2, $check3);
@@ -73,17 +90,16 @@ public function testCollectionId()
         $this->assertEquals($reference1->id, 1);
         $this->assertEquals($reference2->id, 2);
 
-        $check1 = $this->dm->getRepository(__NAMESPACE__.'\CollectionIdUser')->findOneBy(array('id' => $user1->id));
-        $check2 = $this->dm->getRepository(__NAMESPACE__.'\CollectionIdUser')->findOneBy(array('id' => $user2->id));
+        $check1 = $this->dm->getRepository(__NAMESPACE__ . '\CollectionIdUser')->findOneBy(['id' => $user1->id]);
+        $check2 = $this->dm->getRepository(__NAMESPACE__ . '\CollectionIdUser')->findOneBy(['id' => $user2->id]);
         $this->assertNotNull($check1);
         $this->assertNotNull($check2);
 
         $this->assertEquals('referenced 1', $check1->reference->getName());
         $this->assertEquals('referenced 2', $check2->reference->getName());
 
-        $check = $this->dm->getRepository(__NAMESPACE__.'\CollectionIdUser')->find($user1->id);
+        $check = $this->dm->getRepository(__NAMESPACE__ . '\CollectionIdUser')->find($user1->id);
         $this->assertNotNull($check);
-
     }
 
     public function testCollectionIdWithStartingId()
@@ -126,17 +142,17 @@ public function testEmbeddedDocumentWithId()
 
     public function testIdGeneratorInstance()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\UuidUser');
-        $this->assertEquals(\Doctrine\ODM\MongoDB\Mapping\ClassMetadata::GENERATOR_TYPE_UUID, $class->generatorType);
-        $this->assertEquals(array('salt' => 'test'), $class->generatorOptions);
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\UuidUser');
+        $this->assertEquals(ClassMetadata::GENERATOR_TYPE_UUID, $class->generatorType);
+        $this->assertEquals(['salt' => 'test'], $class->generatorOptions);
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\Id\UuidGenerator', $class->idGenerator);
         $this->assertEquals('test', $class->idGenerator->getSalt());
 
         $serialized = serialize($class);
         $class = unserialize($serialized);
 
-        $this->assertEquals(\Doctrine\ODM\MongoDB\Mapping\ClassMetadata::GENERATOR_TYPE_UUID, $class->generatorType);
-        $this->assertEquals(array('salt' => 'test'), $class->generatorOptions);
+        $this->assertEquals(ClassMetadata::GENERATOR_TYPE_UUID, $class->generatorType);
+        $this->assertEquals(['salt' => 'test'], $class->generatorOptions);
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\Id\UuidGenerator', $class->idGenerator);
         $this->assertEquals('test', $class->idGenerator->getSalt());
     }
@@ -146,11 +162,6 @@ public function testIdGeneratorInstance()
      */
     public function testEqualButNotIdenticalIds($user1Id, $user2Id)
     {
-        /* Do not use assertEquals(), since the Scalar comparator tends to cast
-         * scalars of different types to strings before comparison. We actually
-         * want to check against PHP's loose equality logic here.
-         */
-        $this->assertTrue($user1Id == $user2Id);
         $this->assertNotSame($user1Id, $user2Id);
 
         $user1 = new CustomIdUser(sprintf('User1 with %s ID', gettype($user1Id)));
@@ -167,8 +178,8 @@ public function testEqualButNotIdenticalIds($user1Id, $user2Id)
         $this->assertSame($user1->id, $user1Id);
         $this->assertSame($user2->id, $user2Id);
 
-        $user1 = $this->dm->find(__NAMESPACE__.'\CustomIdUser', $user1Id);
-        $user2 = $this->dm->find(__NAMESPACE__.'\CustomIdUser', $user2Id);
+        $user1 = $this->dm->find(__NAMESPACE__ . '\CustomIdUser', $user1Id);
+        $user2 = $this->dm->find(__NAMESPACE__ . '\CustomIdUser', $user2Id);
 
         $this->assertNotSame($user1, $user2);
         $this->assertSame($user1->id, $user1Id);
@@ -182,12 +193,12 @@ public function provideEqualButNotIdenticalIds()
          *
          * See: http://docs.mongodb.org/manual/faq/developers/#what-is-the-compare-order-for-bson-types
          */
-        return array(
-            array('123', 123),
-            array('123', 123.0),
-            array('', 0),
-            array('0', 0),
-        );
+        return [
+            ['123', 123],
+            ['123', 123.0],
+            ['', 0],
+            ['0', 0],
+        ];
     }
 
     /**
@@ -207,7 +218,7 @@ public function testIdTypesAndStrategies($type, $strategy, $id = null, $expected
         $this->assertNotNull($object->id);
 
         if ($expectedMongoType !== null) {
-            $check = $this->dm->getDocumentCollection(get_class($object))->findOne(array());
+            $check = $this->dm->getDocumentCollection(get_class($object))->findOne([]);
             $this->assertEquals($expectedMongoType, is_object($check['_id']) ? get_class($check['_id']) : gettype($check['_id']));
         }
 
@@ -232,59 +243,59 @@ public function testIdTypesAndStrategies($type, $strategy, $id = null, $expected
 
     public function getTestIdTypesAndStrategiesData()
     {
-        $identifier = new \MongoDB\BSON\ObjectId();
+        $identifier = new ObjectId();
 
-        return array(
+        return [
             // boolean
-            array('boolean', 'none', true,  true, 'boolean'),
-            array('boolean', 'none', 1,  true, 'boolean'),
-            array('boolean', 'none', false, false, 'boolean'),
+            ['boolean', 'none', true,  true, 'boolean'],
+            ['boolean', 'none', 1,  true, 'boolean'],
+            ['boolean', 'none', false, false, 'boolean'],
 
             // integer
-            array('int', 'none', 0, 0, 'integer'),
-            array('int', 'none', 1, 1, 'integer'),
-            array('int', 'none', '1', 1, 'integer'),
-            array('int', 'increment', null, 1, 'integer'),
+            ['int', 'none', 0, 0, 'integer'],
+            ['int', 'none', 1, 1, 'integer'],
+            ['int', 'none', '1', 1, 'integer'],
+            ['int', 'increment', null, 1, 'integer'],
 
             // raw
-            array('raw', 'none', 0, 0, 'integer'),
-            array('raw', 'none', '1', '1', 'string'),
-            array('raw', 'none', true, true, 'boolean'),
-            array('raw', 'increment', null, 1, 'integer'),
+            ['raw', 'none', 0, 0, 'integer'],
+            ['raw', 'none', '1', '1', 'string'],
+            ['raw', 'none', true, true, 'boolean'],
+            ['raw', 'increment', null, 1, 'integer'],
 
             // float
-            array('float', 'none', 1.1, 1.1, 'double'),
-            array('float', 'none', '1.1', 1.1, 'double'),
+            ['float', 'none', 1.1, 1.1, 'double'],
+            ['float', 'none', '1.1', 1.1, 'double'],
 
             // string
-            array('string', 'none', '', '', 'string'),
-            array('string', 'none', 1, '1', 'string'),
-            array('string', 'none', 'test', 'test', 'string'),
-            array('string', 'increment', null, '1', 'string'),
+            ['string', 'none', '', '', 'string'],
+            ['string', 'none', 1, '1', 'string'],
+            ['string', 'none', 'test', 'test', 'string'],
+            ['string', 'increment', null, '1', 'string'],
 
             // custom_id
-            array('custom_id', 'none', 0, 0, 'integer'),
-            array('custom_id', 'none', '1', '1', 'string'),
-            array('custom_id', 'increment', null, 1, 'integer'),
+            ['custom_id', 'none', 0, 0, 'integer'],
+            ['custom_id', 'none', '1', '1', 'string'],
+            ['custom_id', 'increment', null, 1, 'integer'],
 
             // object_id
-            array('object_id', 'none', (string) $identifier, (string) $identifier, \MongoDB\BSON\ObjectId::class),
+            ['object_id', 'none', (string) $identifier, (string) $identifier, ObjectId::class],
 
             // date
-            array('date', 'none', new \DateTime(date('Y-m-d')), new \DateTime(date('Y-m-d')), \MongoDB\BSON\UTCDateTime::class),
+            ['date', 'none', new \DateTime(date('Y-m-d')), new \DateTime(date('Y-m-d')), UTCDateTime::class],
 
             // bin
-            array('bin', 'none', 'test-data', 'test-data', \MongoDB\BSON\Binary::class),
-            array('bin', 'uuid', null, null, \MongoDB\BSON\Binary::class),
-            array('bin_func', 'none', 'test-data', 'test-data', \MongoDB\BSON\Binary::class),
-            array('bin_bytearray', 'none', 'test-data', 'test-data', \MongoDB\BSON\Binary::class),
-            array('bin_uuid', 'none', 'TestTestTestTest', 'TestTestTestTest', \MongoDB\BSON\Binary::class),
-            array('bin_md5', 'none', md5('test'), md5('test'), \MongoDB\BSON\Binary::class),
-            array('bin_custom', 'none', 'test-data', 'test-data', \MongoDB\BSON\Binary::class),
+            ['bin', 'none', 'test-data', 'test-data', Binary::class],
+            ['bin', 'uuid', null, null, Binary::class],
+            ['bin_func', 'none', 'test-data', 'test-data', Binary::class],
+            ['bin_bytearray', 'none', 'test-data', 'test-data', Binary::class],
+            ['bin_uuid', 'none', 'TestTestTestTest', 'TestTestTestTest', Binary::class],
+            ['bin_md5', 'none', md5('test'), md5('test'), Binary::class],
+            ['bin_custom', 'none', 'test-data', 'test-data', Binary::class],
 
             // hash
-            array('hash', 'none', array('key' => 'value'), array('key' => 'value'), 'array'),
-        );
+            ['hash', 'none', ['key' => 'value'], ['key' => 'value'], 'array'],
+        ];
     }
 
     /**
@@ -301,22 +312,22 @@ public function testBinIds($type, $expectedMongoBinDataType, $id)
         $this->dm->flush();
         $this->dm->clear();
 
-        $check = $this->dm->getDocumentCollection(get_class($object))->findOne(array());
+        $check = $this->dm->getDocumentCollection(get_class($object))->findOne([]);
 
-        $this->assertEquals(\MongoDB\BSON\Binary::class, get_class($check['_id']));
+        $this->assertEquals(Binary::class, get_class($check['_id']));
         $this->assertEquals($expectedMongoBinDataType, $check['_id']->getType());
     }
 
     public function getTestBinIdsData()
     {
-        return array(
-            array('bin', 0, 'test-data'),
-            array('bin_func', \MongoDB\BSON\Binary::TYPE_FUNCTION, 'test-data'),
-            array('bin_bytearray', \MongoDB\BSON\Binary::TYPE_OLD_BINARY, 'test-data'),
-            array('bin_uuid', \MongoDB\BSON\Binary::TYPE_OLD_UUID, 'testtesttesttest'),
-            array('bin_md5', \MongoDB\BSON\Binary::TYPE_MD5, md5('test')),
-            array('bin_custom', \MongoDB\BSON\Binary::TYPE_USER_DEFINED, 'test-data'),
-        );
+        return [
+            ['bin', 0, 'test-data'],
+            ['bin_func', Binary::TYPE_FUNCTION, 'test-data'],
+            ['bin_bytearray', Binary::TYPE_OLD_BINARY, 'test-data'],
+            ['bin_uuid', Binary::TYPE_OLD_UUID, 'testtesttesttest'],
+            ['bin_md5', Binary::TYPE_MD5, md5('test')],
+            ['bin_custom', Binary::TYPE_USER_DEFINED, 'test-data'],
+        ];
     }
 
     /**
@@ -343,11 +354,11 @@ public function testStrategyAutoWithNotValidIdThrowsException()
     private function createIdTestClass($type, $strategy)
     {
         $shortClassName = sprintf('TestIdTypes%s%sUser', ucfirst($type), ucfirst($strategy));
-        $className = sprintf(__NAMESPACE__.'\\%s', $shortClassName);
+        $className = sprintf(__NAMESPACE__ . '\\%s', $shortClassName);
 
-        if (!class_exists($className)) {
+        if (! class_exists($className)) {
             $code = sprintf(
-'namespace Doctrine\ODM\MongoDB\Tests\Functional;
+                'namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
@@ -359,7 +370,11 @@ class %s
 
     /** @Doctrine\ODM\MongoDB\Mapping\Annotations\Field("type=string") **/
     public $test = "test";
-}', $shortClassName, $strategy, $type);
+}',
+                $shortClassName,
+                $strategy,
+                $type
+            );
 
             eval($code);
         }
@@ -396,7 +411,7 @@ class CollectionIdUser
     public $reference;
 
     /** @ODM\EmbedMany(targetDocument="EmbeddedCollectionId") */
-    public $embedded = array();
+    public $embedded = [];
 
     public function __construct($name)
     {
@@ -417,7 +432,7 @@ class CollectionIdUserWithStartingId
     public $reference;
 
     /** @ODM\EmbedMany(targetDocument="EmbeddedCollectionId") */
-    public $embedded = array();
+    public $embedded = [];
 
     public function __construct($name)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
index a9ff7ce11d..ed35491b6f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
@@ -1,14 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-class IdentifiersTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Event;
+use Documents\User;
+use function get_class;
+
+class IdentifiersTest extends BaseTest
 {
     public function testGetIdentifierValue()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('jwage');
-        $event = new \Documents\Event();
+        $event = new Event();
         $event->setTitle('test event title');
         $event->setUser($user);
         $this->dm->persist($user);
@@ -36,7 +43,7 @@ public function testGetIdentifierValue()
 
     public function testIdentifiersAreSet()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('jwage');
         $user->setPassword('test');
 
@@ -48,7 +55,7 @@ public function testIdentifiersAreSet()
 
     public function testIdentityMap()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('jwage');
 
         $this->dm->persist($user);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IndexesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IndexesTest.php
index e4921f14cc..91f886b145 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IndexesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IndexesTest.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class IndexesTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class IndexesTest extends BaseTest
 {
     private function uniqueTest($class)
     {
-        $class = __NAMESPACE__.'\\'.$class;
+        $class = __NAMESPACE__ . '\\' . $class;
         $this->dm->getSchemaManager()->ensureDocumentIndexes($class);
 
         $test = new $class();
@@ -33,7 +36,7 @@ private function uniqueTest($class)
 
     public function testEmbeddedIndexes()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\DocumentWithEmbeddedIndexes');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\DocumentWithEmbeddedIndexes');
         $sm = $this->dm->getSchemaManager();
         $indexes = $sm->getDocumentIndexes($class->name);
 
@@ -52,7 +55,7 @@ public function testEmbeddedIndexes()
 
     public function testDiscriminatedEmbeddedIndexes()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\DocumentWithIndexInDiscriminatedEmbeds');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\DocumentWithIndexInDiscriminatedEmbeds');
         $sm = $this->dm->getSchemaManager();
         $indexes = $sm->getDocumentIndexes($class->name);
 
@@ -68,7 +71,7 @@ public function testDiscriminatedEmbeddedIndexes()
 
     public function testDiscriminatorIndexes()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\DocumentWithDiscriminatorIndex');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\DocumentWithDiscriminatorIndex');
         $sm = $this->dm->getSchemaManager();
         $indexes = $sm->getDocumentIndexes($class->name);
 
@@ -78,35 +81,35 @@ public function testDiscriminatorIndexes()
 
     public function testIndexDefinitions()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\UniqueOnFieldTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\UniqueOnFieldTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
         $this->assertTrue(isset($indexes[0]['options']['unique']));
         $this->assertEquals(true, $indexes[0]['options']['unique']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\UniqueOnDocumentTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\UniqueOnDocumentTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
         $this->assertTrue(isset($indexes[0]['options']['unique']));
         $this->assertEquals(true, $indexes[0]['options']['unique']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\IndexesOnDocumentTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\IndexesOnDocumentTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
         $this->assertTrue(isset($indexes[0]['options']['unique']));
         $this->assertEquals(true, $indexes[0]['options']['unique']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\PartialIndexOnDocumentTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\PartialIndexOnDocumentTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
         $this->assertTrue(isset($indexes[0]['options']['partialFilterExpression']));
-        $this->assertSame(array('counter' => array('$gt' => 5)), $indexes[0]['options']['partialFilterExpression']);
+        $this->assertSame(['counter' => ['$gt' => 5]], $indexes[0]['options']['partialFilterExpression']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\UniqueSparseOnFieldTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\UniqueSparseOnFieldTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -115,7 +118,7 @@ public function testIndexDefinitions()
         $this->assertTrue(isset($indexes[0]['options']['sparse']));
         $this->assertEquals(true, $indexes[0]['options']['sparse']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\UniqueSparseOnDocumentTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\UniqueSparseOnDocumentTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -124,7 +127,7 @@ public function testIndexDefinitions()
         $this->assertTrue(isset($indexes[0]['options']['sparse']));
         $this->assertEquals(true, $indexes[0]['options']['sparse']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\SparseIndexesOnDocumentTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\SparseIndexesOnDocumentTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -133,7 +136,7 @@ public function testIndexDefinitions()
         $this->assertTrue(isset($indexes[0]['options']['sparse']));
         $this->assertEquals(true, $indexes[0]['options']['sparse']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\MultipleFieldsUniqueIndexTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\MultipleFieldsUniqueIndexTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -142,7 +145,7 @@ public function testIndexDefinitions()
         $this->assertTrue(isset($indexes[0]['options']['unique']));
         $this->assertEquals(true, $indexes[0]['options']['unique']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\MultipleFieldsUniqueSparseIndexTest');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\MultipleFieldsUniqueSparseIndexTest');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -153,7 +156,7 @@ public function testIndexDefinitions()
         $this->assertTrue(isset($indexes[0]['options']['sparse']));
         $this->assertEquals(true, $indexes[0]['options']['sparse']);
 
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\MultipleFieldIndexes');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\MultipleFieldIndexes');
         $indexes = $class->getIndexes();
         $this->assertTrue(isset($indexes[0]['keys']['username']));
         $this->assertEquals(1, $indexes[0]['keys']['username']);
@@ -221,7 +224,7 @@ public function testPartialIndexCreation()
 
         $indexes = $this->dm->getSchemaManager()->getDocumentIndexes($className);
         $this->assertNotEmpty($indexes[0]['options']['partialFilterExpression']);
-        $this->assertSame(array('counter' => array('$gt' => 5)), $indexes[0]['options']['partialFilterExpression']);
+        $this->assertSame(['counter' => ['$gt' => 5]], $indexes[0]['options']['partialFilterExpression']);
         $this->assertTrue($indexes[0]['options']['unique']);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/InheritanceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/InheritanceTest.php
index c5cf9d2f53..9f27b64916 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/InheritanceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/InheritanceTest.php
@@ -1,15 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-class InheritanceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Developer;
+use Documents\OtherSubProject;
+use Documents\Profile;
+use Documents\Project;
+use Documents\SpecialUser;
+use Documents\SubProject;
+use Documents\User;
+
+class InheritanceTest extends BaseTest
 {
     public function testCollectionPerClassInheritance()
     {
-        $profile = new \Documents\Profile();
+        $profile = new Profile();
         $profile->setFirstName('Jon');
 
-        $user = new \Documents\SpecialUser();
+        $user = new SpecialUser();
         $user->setUsername('specialuser');
         $user->setProfile($profile);
 
@@ -33,36 +44,36 @@ public function testCollectionPerClassInheritance()
         $query = $qb->getQuery();
         $user = $query->getSingleResult();
         $this->assertEquals('Wage', $user->getProfile()->getLastName());
-        $this->assertInstanceOf(\Documents\SpecialUser::class, $user);
+        $this->assertInstanceOf(SpecialUser::class, $user);
     }
 
     public function testSingleCollectionInhertiance()
     {
-        $subProject = new \Documents\SubProject('Sub Project');
+        $subProject = new SubProject('Sub Project');
         $this->dm->persist($subProject);
         $this->dm->flush();
 
         $coll = $this->dm->getDocumentCollection('Documents\SubProject');
-        $document = $coll->findOne(array('name' => 'Sub Project'));
+        $document = $coll->findOne(['name' => 'Sub Project']);
         $this->assertEquals('sub-project', $document['type']);
 
-        $project = new \Documents\OtherSubProject('Other Sub Project');
+        $project = new OtherSubProject('Other Sub Project');
         $this->dm->persist($project);
         $this->dm->flush();
 
         $coll = $this->dm->getDocumentCollection('Documents\OtherSubProject');
-        $document = $coll->findOne(array('name' => 'Other Sub Project'));
+        $document = $coll->findOne(['name' => 'Other Sub Project']);
         $this->assertEquals('other-sub-project', $document['type']);
 
         $this->dm->clear();
 
-        $document = $this->dm->getRepository('Documents\SubProject')->findOneBy(array('name' => 'Sub Project'));
+        $document = $this->dm->getRepository('Documents\SubProject')->findOneBy(['name' => 'Sub Project']);
         $this->assertInstanceOf('Documents\SubProject', $document);
 
-        $document = $this->dm->getRepository('Documents\SubProject')->findOneBy(array('name' => 'Sub Project'));
+        $document = $this->dm->getRepository('Documents\SubProject')->findOneBy(['name' => 'Sub Project']);
         $this->assertInstanceOf('Documents\SubProject', $document);
 
-        $document = $this->dm->getRepository('Documents\Project')->findOneBy(array('name' => 'Sub Project'));
+        $document = $this->dm->getRepository('Documents\Project')->findOneBy(['name' => 'Sub Project']);
         $this->assertInstanceOf('Documents\SubProject', $document);
         $this->dm->clear();
 
@@ -70,13 +81,13 @@ public function testSingleCollectionInhertiance()
         $document = $this->dm->find('Documents\Project', $id);
         $this->assertInstanceOf('Documents\SubProject', $document);
 
-        $document = $this->dm->getRepository('Documents\Project')->findOneBy(array('name' => 'Other Sub Project'));
+        $document = $this->dm->getRepository('Documents\Project')->findOneBy(['name' => 'Other Sub Project']);
         $this->assertInstanceOf('Documents\OtherSubProject', $document);
     }
 
     public function testPrePersistIsCalledFromMappedSuperClass()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('test');
         $this->dm->persist($user);
         $this->dm->flush();
@@ -85,13 +96,13 @@ public function testPrePersistIsCalledFromMappedSuperClass()
 
     public function testInheritanceProxy()
     {
-        $developer = new \Documents\Developer('avalanche123');
+        $developer = new Developer('avalanche123');
 
         $projects = $developer->getProjects();
 
-        $projects->add(new \Documents\Project('Main Project'));
-        $projects->add(new \Documents\SubProject('Sub Project'));
-        $projects->add(new \Documents\OtherSubProject('Another Sub Project'));
+        $projects->add(new Project('Main Project'));
+        $projects->add(new SubProject('Sub Project'));
+        $projects->add(new OtherSubProject('Another Sub Project'));
 
         $this->dm->persist($developer);
         $this->dm->flush();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
index ec3569cfba..5cbdb9d4fc 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
@@ -1,9 +1,12 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Iterator;
 
 use Doctrine\ODM\MongoDB\Iterator\CachingIterator;
 use PHPUnit\Framework\TestCase;
+use function iterator_to_array;
 
 class CachingIteratorTest extends TestCase
 {
@@ -54,7 +57,7 @@ public function testIterationWithEmptySet()
 
     public function testPartialIterationDoesNotExhaust()
     {
-        $traversable = $this->getTraversableThatThrows([1, 2, new \Exception]);
+        $traversable = $this->getTraversableThatThrows([1, 2, new \Exception()]);
         $iterator = new CachingIterator($traversable);
 
         $expectedKey = 0;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/HydratingIteratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/HydratingIteratorTest.php
index 34f1a2556d..ab6b6a795a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/HydratingIteratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/HydratingIteratorTest.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Iterator;
 
@@ -6,6 +8,7 @@
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
 use MongoDB\BSON\ObjectId;
+use function is_array;
 
 final class HydratingIteratorTest extends BaseTest
 {
@@ -45,7 +48,7 @@ public function testIterationWithEmptySet()
 
     private function getTraversable($items = null)
     {
-        if (!is_array($items)) {
+        if (! is_array($items)) {
             $items = [
                 ['_id' => new ObjectId(), 'username' => 'foo', 'hits' => 1],
                 ['_id' => new ObjectId(), 'username' => 'bar', 'hits' => 2],
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/PrimingIteratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/PrimingIteratorTest.php
index 82a5055a39..4cdf51c8d0 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/PrimingIteratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/PrimingIteratorTest.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types = 1);
+<?php
+
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Iterator;
 
@@ -7,6 +9,7 @@
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
 use MongoDB\BSON\ObjectId;
+use function is_array;
 
 final class PrimingIteratorTest extends BaseTest
 {
@@ -31,7 +34,7 @@ public function testPrimerIsCalledOnceForEveryField()
 
     private function getIterator($items = null): \Iterator
     {
-        if (!is_array($items)) {
+        if (! is_array($items)) {
             $items = [
                 ['_id' => new ObjectId(), 'username' => 'foo', 'hits' => 1],
                 ['_id' => new ObjectId(), 'username' => 'bar', 'hits' => 2],
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/LifecycleTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/LifecycleTest.php
index ca50638806..b2a9b94311 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/LifecycleTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/LifecycleTest.php
@@ -1,9 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
 class LifecycleTest extends BaseTest
 {
@@ -24,7 +26,7 @@ public function testEventOnDoubleFlush()
 
         $this->dm->clear();
 
-        $parent = $this->dm->getRepository(__NAMESPACE__.'\ParentObject')->find($parent->getId());
+        $parent = $this->dm->getRepository(__NAMESPACE__ . '\ParentObject')->find($parent->getId());
         $this->assertNotNull($parent);
         $this->assertEquals('parent #changed', $parent->getName());
         $this->assertCount(1, $parent->getChildren());
@@ -43,7 +45,7 @@ public function testEventEmptyFlush()
         $this->dm->flush();
         $this->dm->clear();
 
-        $parent = $this->dm->getRepository(__NAMESPACE__.'\ParentObject')->find($parent->getId());
+        $parent = $this->dm->getRepository(__NAMESPACE__ . '\ParentObject')->find($parent->getId());
         $this->assertNotNull($parent);
         $this->assertCount(1, $parent->getChildren());
     }
@@ -86,7 +88,7 @@ public function getName()
     /** @ODM\PrePersist @ODM\PreUpdate */
     public function prePersistPreUpdate()
     {
-        $this->children = array($this->child);
+        $this->children = [$this->child];
     }
 
     /** @ODM\PreUpdate */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/LockTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/LockTest.php
index f215355244..c6112cdadf 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/LockTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/LockTest.php
@@ -1,13 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\LockException;
 use Doctrine\ODM\MongoDB\LockMode;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\MongoDBException;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Issue;
+use Documents\User;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\UTCDateTime;
+use function get_class;
+use function time;
 
-class LockTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class LockTest extends BaseTest
 {
     public function testOptimisticLockIntSetInitialVersion()
     {
@@ -25,7 +35,7 @@ public function testOptimisticLockIntSetInitialVersion()
 
     public function testOptimisticLockIntSetInitialVersionOnUpsert()
     {
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
 
         $article = new LockInt('Test LockInt');
         $article->id = $id;
@@ -49,12 +59,12 @@ public function testOptimisticLockingIntThrowsException()
         $this->dm->flush();
 
         // Manually change the version so the next code will cause an exception
-        $this->dm->getDocumentCollection(get_class($article))->updateOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('$set' => array('version' => 5)));
+        $this->dm->getDocumentCollection(get_class($article))->updateOne(['_id' => new ObjectId($article->id)], ['$set' => ['version' => 5]]);
 
         // Now lets change a property and try and save it again
         $article->title = 'ok';
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->flush();
     }
@@ -78,7 +88,7 @@ public function testLockTimestampSetsDefaultValue()
         $test = new LockTimestamp();
         $test->title = 'Testing';
 
-        $this->assertNull($test->version, "Pre-Condition");
+        $this->assertNull($test->version, 'Pre-Condition');
 
         $this->dm->persist($test);
         $this->dm->flush();
@@ -97,13 +107,13 @@ public function testLockTimestampSetsDefaultValue()
 
     public function testLockTimestampSetsDefaultValueOnUpsert()
     {
-        $id = new \MongoDB\BSON\ObjectId();
+        $id = new ObjectId();
 
         $test = new LockTimestamp();
         $test->title = 'Testing';
         $test->id = $id;
 
-        $this->assertNull($test->version, "Pre-Condition");
+        $this->assertNull($test->version, 'Pre-Condition');
 
         $this->dm->persist($test);
         $this->dm->flush();
@@ -128,12 +138,12 @@ public function testLockTimestampThrowsException()
         $this->dm->flush();
 
         // Manually change the version so the next code will cause an exception
-        $this->dm->getDocumentCollection(get_class($article))->updateOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('$set' => array('version' => new \MongoDB\BSON\UTCDateTime(time() * 1000 + 600))));
+        $this->dm->getDocumentCollection(get_class($article))->updateOne(['_id' => new ObjectId($article->id)], ['$set' => ['version' => new UTCDateTime(time() * 1000 + 600)]]);
 
         // Now lets change a property and try and save it again
         $article->title = 'ok';
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->flush();
     }
@@ -144,7 +154,7 @@ public function testLockTimestampThrowsException()
     public function testLockVersionedDocument()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -155,25 +165,25 @@ public function testLockVersionedDocument()
     public function testLockVersionedDocumentMissmatchThrowsException()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->lock($article, LockMode::OPTIMISTIC, $article->version + 1);
     }
 
     public function testLockUnversionedDocumentThrowsException()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('test');
 
         $this->dm->persist($user);
         $this->dm->flush();
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
         $this->expectExceptionMessage('Document Documents\User is not versioned.');
 
         $this->dm->lock($user, LockMode::OPTIMISTIC);
@@ -192,7 +202,7 @@ public function testLockUnmanagedDocumentThrowsException()
     public function testLockPessimisticWrite()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -206,7 +216,7 @@ public function testLockPessimisticWrite()
     public function testLockPessimisticRead()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -220,7 +230,7 @@ public function testLockPessimisticRead()
     public function testUnlock()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -241,15 +251,15 @@ public function testUnlock()
     public function testPessimisticReadLockThrowsExceptionOnRemove()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $coll = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt');
-        $coll->replaceOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('locked' => LockMode::PESSIMISTIC_READ));
+        $coll = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt');
+        $coll->replaceOne(['_id' => new ObjectId($article->id)], ['locked' => LockMode::PESSIMISTIC_READ]);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->remove($article);
         $this->dm->flush();
@@ -258,15 +268,15 @@ public function testPessimisticReadLockThrowsExceptionOnRemove()
     public function testPessimisticReadLockThrowsExceptionOnUpdate()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $coll = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt');
-        $coll->replaceOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('locked' => LockMode::PESSIMISTIC_READ));
+        $coll = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt');
+        $coll->replaceOne(['_id' => new ObjectId($article->id)], ['locked' => LockMode::PESSIMISTIC_READ]);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $article->title = 'changed';
         $this->dm->flush();
@@ -275,15 +285,15 @@ public function testPessimisticReadLockThrowsExceptionOnUpdate()
     public function testPessimisticWriteLockThrowExceptionOnRemove()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $coll = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt');
-        $coll->replaceOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('locked' => LockMode::PESSIMISTIC_WRITE));
+        $coll = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt');
+        $coll->replaceOne(['_id' => new ObjectId($article->id)], ['locked' => LockMode::PESSIMISTIC_WRITE]);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->remove($article);
         $this->dm->flush();
@@ -292,15 +302,15 @@ public function testPessimisticWriteLockThrowExceptionOnRemove()
     public function testPessimisticWriteLockThrowExceptionOnUpdate()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $coll = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt');
-        $coll->replaceOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('locked' => LockMode::PESSIMISTIC_WRITE));
+        $coll = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt');
+        $coll->replaceOne(['_id' => new ObjectId($article->id)], ['locked' => LockMode::PESSIMISTIC_WRITE]);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $article->title = 'changed';
         $this->dm->flush();
@@ -309,24 +319,24 @@ public function testPessimisticWriteLockThrowExceptionOnUpdate()
     public function testPessimisticWriteLockThrowExceptionOnRead()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
 
-        $coll = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt');
-        $coll->replaceOne(array('_id' => new \MongoDB\BSON\ObjectId($article->id)), array('locked' => LockMode::PESSIMISTIC_WRITE));
+        $coll = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt');
+        $coll->replaceOne(['_id' => new ObjectId($article->id)], ['locked' => LockMode::PESSIMISTIC_WRITE]);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\LockException::class);
+        $this->expectException(LockException::class);
 
         $this->dm->clear();
-        $article = $this->dm->find(__NAMESPACE__.'\LockInt', $article->id);
+        $article = $this->dm->find(__NAMESPACE__ . '\LockInt', $article->id);
     }
 
     public function testPessimisticReadLockFunctional()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -336,7 +346,7 @@ public function testPessimisticReadLockFunctional()
         $article->title = 'test';
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt')->findOne();
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt')->findOne();
         $this->assertEquals(2, $check['version']);
         $this->assertArrayNotHasKey('locked', $check);
         $this->assertEquals('test', $check['title']);
@@ -345,7 +355,7 @@ public function testPessimisticReadLockFunctional()
     public function testPessimisticWriteLockFunctional()
     {
         $article = new LockInt();
-        $article->title = "my article";
+        $article->title = 'my article';
 
         $this->dm->persist($article);
         $this->dm->flush();
@@ -355,7 +365,7 @@ public function testPessimisticWriteLockFunctional()
         $article->title = 'test';
         $this->dm->flush();
 
-        $check = $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt')->findOne();
+        $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt')->findOne();
         $this->assertEquals(2, $check['version']);
         $this->assertArrayNotHasKey('locked', $check);
         $this->assertEquals('test', $check['title']);
@@ -363,16 +373,16 @@ public function testPessimisticWriteLockFunctional()
 
     public function testInvalidLockDocument()
     {
-        $this->expectException(\Doctrine\ODM\MongoDB\MongoDBException::class);
+        $this->expectException(MongoDBException::class);
         $this->expectExceptionMessage('Invalid lock field type string. Lock field must be int.');
-        $this->dm->getClassMetadata(__NAMESPACE__.'\InvalidLockDocument');
+        $this->dm->getClassMetadata(__NAMESPACE__ . '\InvalidLockDocument');
     }
 
     public function testInvalidVersionDocument()
     {
-        $this->expectException(\Doctrine\ODM\MongoDB\MongoDBException::class);
+        $this->expectException(MongoDBException::class);
         $this->expectExceptionMessage('Invalid version field type string. Version field must be int or date.');
-        $this->dm->getClassMetadata(__NAMESPACE__.'\InvalidVersionDocument');
+        $this->dm->getClassMetadata(__NAMESPACE__ . '\InvalidVersionDocument');
     }
 
     /**
@@ -386,13 +396,13 @@ public function testUpdatingCollectionRespectsVersionNumber()
         $this->dm->flush();
 
         // simulate another request updating document in the meantime
-        $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt')->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($d->id)),
-            array('$set' => array('version' => 2))
+        $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt')->updateOne(
+            ['_id' => new ObjectId($d->id)],
+            ['$set' => ['version' => 2]]
         );
 
         $d->issues->add(new Issue('oops', 'version mismatch'));
-        $this->uow->getCollectionPersister()->update($d->issues, array());
+        $this->uow->getCollectionPersister()->update($d->issues, []);
     }
 
     /**
@@ -406,12 +416,12 @@ public function testDeletingCollectionRespectsVersionNumber()
         $this->dm->flush();
 
         // simulate another request updating document in the meantime
-        $this->dm->getDocumentCollection(__NAMESPACE__.'\LockInt')->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($d->id)),
-            array('$set' => array('version' => 2))
+        $this->dm->getDocumentCollection(__NAMESPACE__ . '\LockInt')->updateOne(
+            ['_id' => new ObjectId($d->id)],
+            ['$set' => ['version' => 2]]
         );
 
-        $this->uow->getCollectionPersister()->delete($d->issues, array());
+        $this->uow->getCollectionPersister()->delete($d->issues, []);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
index bb3a308a10..29f2e98b5a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
@@ -1,19 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MappedSuperclassTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MappedSuperclassTest extends BaseTest
 {
     public function testCRUD()
     {
-        $e = new DocumentSubClass;
+        $e = new DocumentSubClass();
         $e->setId(1);
         $e->setName('Roman');
         $e->setMapped1(42);
         $e->setMapped2('bar');
-        
+
         $related = new MappedSuperclassRelated1();
         $related->setId(1);
         $related->setName('Related');
@@ -29,7 +32,7 @@ public function testCRUD()
         $this->assertEquals(1, $e2->getId());
         $this->assertEquals('Roman', $e2->getName());
         $this->assertNotNull($e2->getMappedRelated1());
-        $this->assertInstanceOf(__NAMESPACE__.'\MappedSuperclassRelated1', $e2->getMappedRelated1());
+        $this->assertInstanceOf(__NAMESPACE__ . '\MappedSuperclassRelated1', $e2->getMappedRelated1());
         $this->assertEquals(42, $e2->getMapped1());
         $this->assertEquals('bar', $e2->getMapped2());
     }
@@ -95,17 +98,17 @@ public function setName($name)
     {
         $this->name = $name;
     }
-    
+
     public function getName()
     {
         return $this->name;
     }
-    
+
     public function setId($id)
     {
         $this->id = $id;
     }
-    
+
     public function getId()
     {
         return $this->id;
@@ -120,22 +123,22 @@ class DocumentSubClass extends MappedSuperclassBase
 
     /** @ODM\Field(type="string") */
     private $name;
-    
+
     public function setName($name)
     {
         $this->name = $name;
     }
-    
+
     public function getName()
     {
         return $this->name;
     }
-    
+
     public function setId($id)
     {
         $this->id = $id;
     }
-    
+
     public function getId()
     {
         return $this->id;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MemoryUsageTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MemoryUsageTest.php
index 24d1221c76..5156665265 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MemoryUsageTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MemoryUsageTest.php
@@ -1,21 +1,33 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsPhonenumber;
 use Documents\CmsUser;
+use function current;
+use function end;
+use function floor;
+use function gc_collect_cycles;
+use function log;
+use function memory_get_usage;
+use function pow;
+use function round;
+use function sprintf;
 
 /**
  * @group performance
  */
-class MemoryUsageTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MemoryUsageTest extends BaseTest
 {
     /**
      * Output for jwage "Memory increased by 14.09 kb"
      */
     public function testMemoryUsage()
     {
-        $memoryUsage = array();
+        $memoryUsage = [];
         for ($i = 0; $i < 100; $i++) {
             $ph1 = new CmsPhonenumber();
             $ph1->phonenumber = '12345';
@@ -46,7 +58,7 @@ public function testMemoryUsage()
 
     private function formatMemory($size)
     {
-        $unit = array('b', 'kb', 'mb', 'gb', 'tb', 'pb');
+        $unit = ['b', 'kb', 'mb', 'gb', 'tb', 'pb'];
         return round($size / pow(1024, ($i = floor(log($size, 1024)))), 2) . ' ' . $unit[$i];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedCollectionsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedCollectionsTest.php
index dfb8a6a49f..57ff80f071 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedCollectionsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedCollectionsTest.php
@@ -1,13 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Phonebook;
 use Documents\Phonenumber;
+use function get_class;
 
-class NestedCollectionsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class NestedCollectionsTest extends BaseTest
 {
     /**
      * @dataProvider provideStrategy
@@ -63,14 +67,14 @@ public function testStrategy($field)
 
     public function provideStrategy()
     {
-        return array(
-            array(ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET),
-            array(ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY),
-            array(ClassMetadata::STORAGE_STRATEGY_SET),
-            array(ClassMetadata::STORAGE_STRATEGY_SET_ARRAY),
-            array(ClassMetadata::STORAGE_STRATEGY_PUSH_ALL),
-            array(ClassMetadata::STORAGE_STRATEGY_ADD_TO_SET),
-        );
+        return [
+            [ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET],
+            [ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY],
+            [ClassMetadata::STORAGE_STRATEGY_SET],
+            [ClassMetadata::STORAGE_STRATEGY_SET_ARRAY],
+            [ClassMetadata::STORAGE_STRATEGY_PUSH_ALL],
+            [ClassMetadata::STORAGE_STRATEGY_ADD_TO_SET],
+        ];
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
index 73816a252a..0f2b32004b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
@@ -1,11 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
+use function is_numeric;
+use function is_string;
 
-class NestedDocumentsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class NestedDocumentsTest extends BaseTest
 {
     public function testSimple()
     {
@@ -27,14 +33,14 @@ public function testSimple()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getDocumentCollection(__NAMESPACE__.'\Order')->findOne();
+        $test = $this->dm->getDocumentCollection(__NAMESPACE__ . '\Order')->findOne();
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $test['product']['_id']);
+        $this->assertInstanceOf(ObjectId::class, $test['product']['_id']);
         $this->assertEquals('Order', $test['title']);
         $this->assertEquals('Product', $test['product']['title']);
 
-        $doc = $this->dm->find(__NAMESPACE__.'\Order', $order->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\Order', $order);
+        $doc = $this->dm->find(__NAMESPACE__ . '\Order', $order->id);
+        $this->assertInstanceOf(__NAMESPACE__ . '\Order', $order);
         $this->assertInternalType('string', $doc->product->id);
         $this->assertEquals((string) $test['product']['_id'], $doc->product->id);
         $this->assertEquals('Order', $doc->title);
@@ -42,22 +48,22 @@ public function testSimple()
 
         $this->dm->clear();
 
-        $order = $this->dm->find(__NAMESPACE__.'\Order', $order->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\Order', $order);
+        $order = $this->dm->find(__NAMESPACE__ . '\Order', $order->id);
+        $this->assertInstanceOf(__NAMESPACE__ . '\Order', $order);
 
-        $product = $this->dm->find(__NAMESPACE__.'\Product', $product->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\Product', $product);
+        $product = $this->dm->find(__NAMESPACE__ . '\Product', $product->id);
+        $this->assertInstanceOf(__NAMESPACE__ . '\Product', $product);
 
         $order->product->title = 'tesgttttt';
         $this->dm->flush();
         $this->dm->clear();
 
-        $test1 = $this->dm->getDocumentCollection(__NAMESPACE__.'\Product')->findOne();
-        $test2 = $this->dm->getDocumentCollection(__NAMESPACE__.'\Order')->findOne();
+        $test1 = $this->dm->getDocumentCollection(__NAMESPACE__ . '\Product')->findOne();
+        $test2 = $this->dm->getDocumentCollection(__NAMESPACE__ . '\Order')->findOne();
         $this->assertNotEquals($test1['title'], $test2['product']['title']);
 
-        $order = $this->dm->find(__NAMESPACE__.'\Order', $order->id);
-        $product = $this->dm->find(__NAMESPACE__.'\Product', $product->id);
+        $order = $this->dm->find(__NAMESPACE__ . '\Order', $order->id);
+        $product = $this->dm->find(__NAMESPACE__ . '\Product', $product->id);
         $this->assertNotEquals($product->title, $order->product->title);
     }
 
@@ -70,7 +76,7 @@ public function testNestedCategories()
         $this->dm->flush();
         $this->dm->clear();
 
-        $category = $this->dm->find(__NAMESPACE__.'\Category', $category->getId());
+        $category = $this->dm->find(__NAMESPACE__ . '\Category', $category->getId());
         $this->assertNotNull($category);
         $category->setName('Root Changed');
         $children = $category->getChildren();
@@ -81,7 +87,7 @@ public function testNestedCategories()
         $this->dm->flush();
         $this->dm->clear();
 
-        $category = $this->dm->find(__NAMESPACE__.'\Category', $category->getId());
+        $category = $this->dm->find(__NAMESPACE__ . '\Category', $category->getId());
 
         $children = $category->getChildren();
         $this->assertEquals('Child 1 Changed', $children[0]->getName());
@@ -101,7 +107,7 @@ public function testNestedReference()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository(__NAMESPACE__.'\Hierarchy')->findOneBy(array('name' => 'Root'));
+        $test = $this->dm->getRepository(__NAMESPACE__ . '\Hierarchy')->findOneBy(['name' => 'Root']);
 
         $this->assertNotNull($test);
         $child1 = $test->getChild('Child 1')->setName('Child 1 Changed');
@@ -112,22 +118,22 @@ public function testNestedReference()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->find(__NAMESPACE__.'\Hierarchy', $test->getId());
+        $test = $this->dm->find(__NAMESPACE__ . '\Hierarchy', $test->getId());
         $this->assertNotNull($test);
         $this->assertEquals('Root Changed', $test->getName());
         $this->assertEquals('Child 1 Changed', $test->getChild(0)->getName());
         $this->assertEquals('Child 2 Changed', $test->getChild(1)->getName());
 
-        $child3 = $this->dm->getRepository(__NAMESPACE__.'\Hierarchy')->findOneBy(array('name' => 'Child 3'));
+        $child3 = $this->dm->getRepository(__NAMESPACE__ . '\Hierarchy')->findOneBy(['name' => 'Child 3']);
         $this->assertNotNull($child3);
         $child3->setName('Child 3 Changed');
         $this->dm->flush();
 
-        $child3 = $this->dm->getRepository(__NAMESPACE__.'\Hierarchy')->findOneBy(array('name' => 'Child 3 Changed'));
+        $child3 = $this->dm->getRepository(__NAMESPACE__ . '\Hierarchy')->findOneBy(['name' => 'Child 3 Changed']);
         $this->assertNotNull($child3);
         $this->assertEquals('Child 3 Changed', $child3->getName());
 
-        $test = $this->dm->getDocumentCollection(__NAMESPACE__.'\Hierarchy')->findOne(array('name' => 'Child 1 Changed'));
+        $test = $this->dm->getDocumentCollection(__NAMESPACE__ . '\Hierarchy')->findOne(['name' => 'Child 1 Changed']);
         $this->assertArrayNotHasKey('children', $test, 'Test empty array is not stored');
     }
 }
@@ -142,7 +148,7 @@ class Hierarchy
     private $name;
 
     /** @ODM\ReferenceMany(targetDocument="Hierarchy") */
-    private $children = array();
+    private $children = [];
 
     public function __construct($name)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalEmbedTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalEmbedTest.php
index 2da2f47a3d..e961772e8b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalEmbedTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalEmbedTest.php
@@ -1,13 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\DocumentRepository;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
 /**
  * Test the orphan removal on embedded documents that contain references with cascade operations.
  */
-class OrphanRemovalEmbedTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class OrphanRemovalEmbedTest extends BaseTest
 {
     /**
      * Test unsetting an embedOne relationship
@@ -137,7 +141,7 @@ public function testClearAndAddEmbedMany()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentRepository
+     * @return DocumentRepository
      */
     private function getUserRepository()
     {
@@ -145,7 +149,7 @@ private function getUserRepository()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentRepository
+     * @return DocumentRepository
      */
     private function getAddressRepository()
     {
@@ -163,7 +167,7 @@ class OrphanRemovalCascadeUser
     public $profile;
 
     /** @ODM\EmbedMany(targetDocument="OrphanRemovalCascadeProfile") */
-    public $profileMany = array();
+    public $profileMany = [];
 }
 
 /** @ODM\EmbeddedDocument */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalTest.php
index 02979f6a57..37bb9fd98f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OrphanRemovalTest.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\DocumentRepository;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class OrphanRemovalTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class OrphanRemovalTest extends BaseTest
 {
     public function testOrphanRemoval()
     {
@@ -241,7 +245,7 @@ public function testOrphanRemovalWhenRemovingAndAddingSameElement()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentRepository
+     * @return DocumentRepository
      */
     private function getUserRepository()
     {
@@ -249,7 +253,7 @@ private function getUserRepository()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentRepository
+     * @return DocumentRepository
      */
     private function getProfileRepository()
     {
@@ -270,10 +274,10 @@ class OrphanRemovalUser
     public $profileNoOrphanRemoval;
 
     /** @ODM\ReferenceMany(targetDocument="OrphanRemovalProfile", orphanRemoval=true) */
-    public $profileMany = array();
+    public $profileMany = [];
 
     /** @ODM\ReferenceMany(targetDocument="OrphanRemovalProfile", orphanRemoval=false) */
-    public $profileManyNoOrphanRemoval = array();
+    public $profileManyNoOrphanRemoval = [];
 }
 
 /** @ODM\Document */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OwningAndInverseReferencesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OwningAndInverseReferencesTest.php
index bc24224863..842e16e494 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/OwningAndInverseReferencesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/OwningAndInverseReferencesTest.php
@@ -1,10 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use DateTime;
-
-class OwningAndInverseReferencesTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\BlogPost;
+use Documents\BrowseNode;
+use Documents\Cart;
+use Documents\Comment;
+use Documents\Customer;
+use Documents\Feature;
+use Documents\FriendUser;
+use Documents\Product;
+use Documents\Tag;
+use function get_class;
+use function strtotime;
+
+class OwningAndInverseReferencesTest extends BaseTest
 {
     public function testOneToOne()
     {
@@ -16,9 +30,9 @@ public function testOneToOne()
         // if inversedBy then isOwningSide
         // if mappedBy then isInverseSide
 
-        $customer = new \Documents\Customer;
+        $customer = new Customer();
         $customer->name = 'Jon Wage';
-        $customer->cart = new \Documents\Cart;
+        $customer->cart = new Cart();
         $customer->cart->numItems = 5;
         $customer->cart->customer = $customer;
         $customer->cartTest = 'test';
@@ -51,9 +65,9 @@ public function testOneToOne()
 
     public function testOneToManyBiDirectional()
     {
-        $product = new \Documents\Product('Book');
-        $product->addFeature(new \Documents\Feature('Pages'));
-        $product->addFeature(new \Documents\Feature('Cover'));
+        $product = new Product('Book');
+        $product->addFeature(new Feature('Pages'));
+        $product->addFeature(new Feature('Cover'));
         $this->dm->persist($product);
         $this->dm->flush();
         $this->dm->clear();
@@ -75,15 +89,15 @@ public function testOneToManyBiDirectional()
 
     public function testOneToManySelfReferencing()
     {
-        $node = new \Documents\BrowseNode('Root');
-        $node->addChild(new \Documents\BrowseNode('Child 1'));
-        $node->addChild(new \Documents\BrowseNode('Child 2'));
+        $node = new BrowseNode('Root');
+        $node->addChild(new BrowseNode('Child 1'));
+        $node->addChild(new BrowseNode('Child 2'));
 
         $this->dm->persist($node);
         $this->dm->flush();
         $this->dm->clear();
 
-        $check = $this->dm->getDocumentCollection(get_class($node))->findOne(array('parent' => array('$exists' => false)));
+        $check = $this->dm->getDocumentCollection(get_class($node))->findOne(['parent' => ['$exists' => false]]);
         $this->assertNotNull($check);
         $this->assertArrayNotHasKey('children', $check);
 
@@ -105,8 +119,8 @@ public function testOneToManySelfReferencing()
 
     public function testManyToMany()
     {
-        $baseballTag = new \Documents\Tag('baseball');
-        $blogPost = new \Documents\BlogPost();
+        $baseballTag = new Tag('baseball');
+        $blogPost = new BlogPost();
         $blogPost->name = 'Test';
         $blogPost->addTag($baseballTag);
 
@@ -137,10 +151,10 @@ public function testManyToMany()
 
     public function testManyToManySelfReferencing()
     {
-        $jwage = new \Documents\FriendUser('jwage');
-        $fabpot = new \Documents\FriendUser('fabpot');
+        $jwage = new FriendUser('jwage');
+        $fabpot = new FriendUser('fabpot');
         $fabpot->addFriend($jwage);
-        $romanb = new \Documents\FriendUser('romanb');
+        $romanb = new FriendUser('romanb');
         $romanb->addFriend($jwage);
         $jwage->addFriend($fabpot);
         $jwage->addFriend($romanb);
@@ -202,9 +216,9 @@ public function testSortLimitAndSkipReferences()
         $date2 = new DateTime();
         $date2->setTimestamp(strtotime('-10 seconds'));
 
-        $blogPost = new \Documents\BlogPost('Test');
-        $blogPost->addComment(new \Documents\Comment('Comment 1', $date1));
-        $blogPost->addComment(new \Documents\Comment('Comment 2', $date2));
+        $blogPost = new BlogPost('Test');
+        $blogPost->addComment(new Comment('Comment 1', $date1));
+        $blogPost->addComment(new Comment('Comment 2', $date2));
 
         $this->dm->persist($blogPost);
         $this->dm->flush();
@@ -243,8 +257,8 @@ public function testSortLimitAndSkipReferences()
             ->getQuery()
             ->getSingleResult();
 
-        $blogPost->addComment(new \Documents\Comment('Comment 3 by admin', $date1, true));
-        $blogPost->addComment(new \Documents\Comment('Comment 4 by admin', $date2, true));
+        $blogPost->addComment(new Comment('Comment 3 by admin', $date1, true));
+        $blogPost->addComment(new Comment('Comment 4 by admin', $date2, true));
         $this->dm->flush();
         $this->dm->clear();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistentCollectionCloneTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistentCollectionCloneTest.php
index 907662423d..9479ae494e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistentCollectionCloneTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistentCollectionCloneTest.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\CmsUser;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsGroup;
+use Documents\CmsUser;
+use function get_class;
 
-class PersistentCollectionCloneTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class PersistentCollectionCloneTest extends BaseTest
 {
     private $user1;
     private $user2;
@@ -15,19 +19,19 @@ public function setUp()
         parent::setUp();
 
         $user1 = new CmsUser();
-        $user1->username = "beberlei";
-        $user1->name = "Benjamin";
-        $user1->status = "active";
+        $user1->username = 'beberlei';
+        $user1->name = 'Benjamin';
+        $user1->status = 'active';
         $group1 = new CmsGroup();
-        $group1->name = "test";
+        $group1->name = 'test';
         $group2 = new CmsGroup();
-        $group2->name = "test";
+        $group2->name = 'test';
         $user1->addGroup($group1);
         $user1->addGroup($group2);
         $user2 = new CmsUser();
-        $user2->username = "romanb";
-        $user2->name = "Roman";
-        $user2->status = "active";
+        $user2->username = 'romanb';
+        $user2->name = 'Roman';
+        $user2->status = 'active';
 
         $this->dm->persist($user1);
         $this->dm->persist($user2);
@@ -77,7 +81,7 @@ public function testCloneThenDirtyPersistentCollection()
         $user2 = $this->user2;
 
         $group3 = new CmsGroup();
-        $group3->name = "test";
+        $group3->name = 'test';
         $user2->groups = clone $user1->groups;
         $user2->groups->add($group3);
 
@@ -98,7 +102,7 @@ public function testNotCloneAndPassAroundFlush()
         $user2 = $this->user2;
 
         $group3 = new CmsGroup();
-        $group3->name = "test";
+        $group3->name = 'test';
         $user2->groups = $user1->groups;
         $user2->groups->add($group3);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistingTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistingTest.php
index cbeaea76a2..c9f6d929f8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistingTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PersistingTest.php
@@ -1,14 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Doctrine\ODM\MongoDB\Mongo;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Account;
-use Documents\Address;
-use Documents\Phonenumber;
 use Documents\User;
 
-class PersistingTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class PersistingTest extends BaseTest
 {
     public function testCascadeInsertUpdateAndRemove()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PrePersistTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PrePersistTest.php
index 2f36d88787..6b1e91e485 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/PrePersistTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/PrePersistTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class PrePersistTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class PrePersistTest extends BaseTest
 {
     public function testPrePersist()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/QueryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/QueryTest.php
index cf33ca2cbc..3aedceed67 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/QueryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/QueryTest.php
@@ -1,15 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Article;
-use Documents\Account;
-use Documents\Address;
 use Documents\CmsComment;
+use Documents\Group;
 use Documents\Phonenumber;
 use Documents\User;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\UTCDateTime;
+use function array_values;
+use function get_class;
+use function strtotime;
 
-class QueryTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class QueryTest extends BaseTest
 {
     public function setUp()
     {
@@ -58,7 +65,7 @@ public function testAddElemMatchWithDeepFields()
         $qb = $this->dm->createQueryBuilder('Documents\User');
         $embeddedQb = $this->dm->createQueryBuilder('Documents\Phonenumber');
 
-        $qb->field('phonenumbers')->elemMatch($embeddedQb->expr()->field('lastCalledBy.$id')->equals(new \MongoDB\BSON\ObjectId($user1->getId())));
+        $qb->field('phonenumbers')->elemMatch($embeddedQb->expr()->field('lastCalledBy.$id')->equals(new ObjectId($user1->getId())));
         $query = $qb->getQuery();
         $user = $query->getSingleResult();
         $this->assertNotNull($user);
@@ -73,12 +80,12 @@ public function testAddNot()
         $this->dm->flush();
 
         $qb = $this->dm->createQueryBuilder('Documents\User');
-        $qb->field('username')->not($qb->expr()->in(array('boo')));
+        $qb->field('username')->not($qb->expr()->in(['boo']));
         $query = $qb->getQuery();
         $user = $query->getSingleResult();
         $this->assertNull($user);
 
-        $qb->field('username')->not($qb->expr()->in(array('1boo')));
+        $qb->field('username')->not($qb->expr()->in(['1boo']));
         $query = $qb->getQuery();
         $user = $query->getSingleResult();
         $this->assertNotNull($user);
@@ -112,23 +119,23 @@ public function testDistinct()
             ->field('username')->equals('distinct_test');
         $q = $qb->getQuery();
         $results = $q->execute();
-        $this->assertEquals(array(1, 2, 3), $results);
+        $this->assertEquals([1, 2, 3], $results);
 
         $results = $this->dm->createQueryBuilder('Documents\User')
             ->distinct('count')
             ->field('username')->equals('distinct_test')
             ->getQuery()
             ->execute();
-        $this->assertEquals(array(1, 2, 3), $results);
+        $this->assertEquals([1, 2, 3], $results);
     }
 
     public function testDistinctWithDifferentDbName()
     {
         $c1 = new CmsComment();
-        $c1->authorIp = "127.0.0.1";
+        $c1->authorIp = '127.0.0.1';
         $c2 = new CmsComment();
         $c3 = new CmsComment();
-        $c2->authorIp = $c3->authorIp = "192.168.0.1";
+        $c2->authorIp = $c3->authorIp = '192.168.0.1';
         $this->dm->persist($c1);
         $this->dm->persist($c2);
         $this->dm->persist($c3);
@@ -139,7 +146,7 @@ public function testDistinctWithDifferentDbName()
             ->distinct('authorIp')
             ->getQuery()
             ->execute();
-        $this->assertEquals(array("127.0.0.1", "192.168.0.1"), $results);
+        $this->assertEquals(['127.0.0.1', '192.168.0.1'], $results);
     }
 
     public function testFindQuery()
@@ -316,8 +323,8 @@ public function testDateRange()
 
         $qb = $this->dm->createQueryBuilder('Documents\Article');
         $qb->field('createdAt')->range(
-            new \MongoDB\BSON\UTCDateTime(strtotime('1985-09-01 01:00:00') * 1000),
-            new \MongoDB\BSON\UTCDateTime(strtotime('1985-09-04') * 1000)
+            new UTCDateTime(strtotime('1985-09-01 01:00:00') * 1000),
+            new UTCDateTime(strtotime('1985-09-04') * 1000)
         );
         $query = $qb->getQuery();
         $articles = array_values($query->execute()->toArray());
@@ -343,7 +350,7 @@ public function testQueryIsIterable()
 
     public function testQueryReferences()
     {
-        $group = new \Documents\Group('Test Group');
+        $group = new Group('Test Group');
 
         $user = new User();
         $user->setUsername('cool');
@@ -362,26 +369,22 @@ public function testQueryReferences()
     public function testQueryWhereIn()
     {
         $qb = $this->dm->createQueryBuilder('Documents\User');
-        $choices = array('a', 'b');
+        $choices = ['a', 'b'];
         $qb->field('username')->in($choices);
-        $expected = array(
-            'username' => array(
-                '$in' => $choices
-            )
-        );
+        $expected = [
+            'username' => ['$in' => $choices],
+        ];
         $this->assertSame($expected, $qb->getQueryArray());
     }
 
     public function testQueryWhereInReferenceId()
     {
         $qb = $this->dm->createQueryBuilder('Documents\User');
-        $choices = array(new \MongoDB\BSON\ObjectId(), new \MongoDB\BSON\ObjectId());
+        $choices = [new ObjectId(), new ObjectId()];
         $qb->field('account.$id')->in($choices);
-        $expected = array(
-            'account.$id' => array(
-                '$in' => $choices
-            )
-        );
+        $expected = [
+            'account.$id' => ['$in' => $choices],
+        ];
         $this->assertSame($expected, $qb->getQueryArray());
         $this->assertSame($expected, $qb->getQuery()->debug('query'));
     }
@@ -391,9 +394,7 @@ public function testQueryWhereOneValueOfCollection()
     {
         $qb = $this->dm->createQueryBuilder('Documents\Article');
         $qb->field('tags')->equals('pet');
-        $expected = array(
-            'tags' => 'pet'
-        );
+        $expected = ['tags' => 'pet'];
         $this->assertSame($expected, $qb->getQueryArray());
         $this->assertSame($expected, $qb->getQuery()->debug('query'));
     }
@@ -402,10 +403,10 @@ public function testQueryWhereOneValueOfCollection()
     public function testQueryWhereAllValuesOfCollection()
     {
         $qb = $this->dm->createQueryBuilder('Documents\Article');
-        $qb->field('tags')->equals(array('pet', 'blue'));
-        $expected = array(
-            'tags' => array('pet', 'blue')
-        );
+        $qb->field('tags')->equals(['pet', 'blue']);
+        $expected = [
+            'tags' => ['pet', 'blue'],
+        ];
         $this->assertSame($expected, $qb->getQueryArray());
         $this->assertSame($expected, $qb->getQuery()->debug('query'));
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RawTypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RawTypeTest.php
index 397916ed7b..7c0930a57f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RawTypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RawTypeTest.php
@@ -1,47 +1,53 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\UTCDateTime;
+use function get_class;
 
-class RawTypeTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class RawTypeTest extends BaseTest
 {
-	/**
-	 * @dataProvider getTestRawTypeData
-	 */
-	public function testRawType($value)
-	{
-		$test = new RawType();
-		$test->raw = $value;
-
-		$this->dm->persist($test);
-		$this->dm->flush();
-
-		$result = $this->dm->getDocumentCollection(get_class($test))->findOne(array('_id' => new \MongoDB\BSON\ObjectId($test->id)));
-		$this->assertEquals($value, $result['raw']);
-	}
-
-	public function getTestRawTypeData()
-	{
-		return array(
-			array('test'),
-			array(1),
-			array(0),
-			array(array('test' => 'test')),
-			array(new \MongoDB\BSON\UTCDateTime()),
-			array(true),
-			array(array('date' => new \MongoDB\BSON\UTCDateTime())),
-			array(new \MongoDB\BSON\ObjectId())
-		);
-	}
+    /**
+     * @dataProvider getTestRawTypeData
+     */
+    public function testRawType($value)
+    {
+        $test = new RawType();
+        $test->raw = $value;
+
+        $this->dm->persist($test);
+        $this->dm->flush();
+
+        $result = $this->dm->getDocumentCollection(get_class($test))->findOne(['_id' => new ObjectId($test->id)]);
+        $this->assertEquals($value, $result['raw']);
+    }
+
+    public function getTestRawTypeData()
+    {
+        return [
+            ['test'],
+            [1],
+            [0],
+            [['test' => 'test']],
+            [new UTCDateTime()],
+            [true],
+            [['date' => new UTCDateTime()]],
+            [new ObjectId()],
+        ];
+    }
 }
 
 /** @ODM\Document */
 class RawType
 {
-	/** @ODM\Id */
-	public $id;
+    /** @ODM\Id */
+    public $id;
 
-	/** @ODM\Field(type="raw") */
-	public $raw;
+    /** @ODM\Field(type="raw") */
+    public $raw;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadOnlyDocumentTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadOnlyDocumentTest.php
index 22b9000576..6b0f4d518a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadOnlyDocumentTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadOnlyDocumentTest.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use MongoDB\BSON\ObjectId;
 
-class ReadOnlyDocumentTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReadOnlyDocumentTest extends BaseTest
 {
     public function testCanBeInserted()
     {
@@ -53,7 +56,7 @@ public function testChangingValueDoesNotProduceChangeSet()
         $rod = new ReadOnlyDocument('yay');
         $this->dm->persist($rod);
         $this->dm->flush();
-        $rod->value = "o.O";
+        $rod->value = 'o.O';
         $this->uow->recomputeSingleDocumentChangeSet($this->dm->getClassMetadata(ReadOnlyDocument::class), $rod);
         $this->assertEmpty($this->uow->getDocumentChangeSet($rod));
     }
@@ -66,7 +69,7 @@ public function testCantBeUpdated()
         $this->dm->clear();
 
         $rod = $this->dm->find(ReadOnlyDocument::class, $rod->id);
-        $rod->value = "o.O";
+        $rod->value = 'o.O';
         $this->dm->flush();
         $this->dm->clear();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadPreferenceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadPreferenceTest.php
index ee45de1bc6..fe616141a4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadPreferenceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReadPreferenceTest.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Group;
 use Documents\User;
 use MongoDB\Driver\ReadPreference;
 
-class ReadPreferenceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReadPreferenceTest extends BaseTest
 {
     public function setUp()
     {
@@ -85,7 +88,7 @@ public function testDocumentLevelReadPreferenceCanBeOverriddenInQueryBuilder()
     {
         $query = $this->dm->getRepository(DocumentWithReadPreference::class)
             ->createQueryBuilder()
-            ->setReadPreference(new ReadPreference("secondary", []))
+            ->setReadPreference(new ReadPreference('secondary', []))
             ->getQuery();
 
         $this->assertReadPreferenceHint(ReadPreference::RP_SECONDARY, $query->getQuery()['readPreference']);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceDiscriminatorsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceDiscriminatorsTest.php
index 18a19893b4..817ad1f63b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceDiscriminatorsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceDiscriminatorsTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class ReferenceDiscriminatorsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferenceDiscriminatorsTest extends BaseTest
 {
     public function setUp()
     {
@@ -88,11 +91,11 @@ public function testReferenceDiscriminatorsRaceCondition()
 }
 
 /**
-* @ODM\Document(collection="rdt_action")
-* @ODM\InheritanceType("SINGLE_COLLECTION")
-* @ODM\DiscriminatorField("discriminator")
-* @ODM\DiscriminatorMap({"action"="Action", "commentable_action"="CommentableAction"})
-*/
+ * @ODM\Document(collection="rdt_action")
+ * @ODM\InheritanceType("SINGLE_COLLECTION")
+ * @ODM\DiscriminatorField("discriminator")
+ * @ODM\DiscriminatorMap({"action"="Action", "commentable_action"="CommentableAction"})
+ */
 class Action
 {
     /** @ODM\Id */
@@ -123,9 +126,9 @@ class CommentableAction extends Action
     /**
      * @ODM\Field(type="collection")
      **/
-    protected $comments = array();
+    protected $comments = [];
 
-    public function __construct($type, array $comments = array())
+    public function __construct($type, array $comments = [])
     {
         parent::__construct($type);
         $this->comments = $comments;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceEmbeddedDocumentsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceEmbeddedDocumentsTest.php
index b94df3b6af..eb7bd82f39 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceEmbeddedDocumentsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceEmbeddedDocumentsTest.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Documents\SubProject;
-use Documents\Project;
-use Documents\Issue;
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Issue;
+use Documents\Project;
+use Documents\SubProject;
 
-class ReferenceEmbeddedDocumentsTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferenceEmbeddedDocumentsTest extends BaseTest
 {
     public function testSavesEmbeddedDocumentsInReferencedDocument()
     {
@@ -23,15 +26,15 @@ public function testSavesEmbeddedDocumentsInReferencedDocument()
         $subProject1 = new SubProject('Sub Project #1');
         $subProject2 = new SubProject('Sub Project #2');
 
-        $subProject1->setIssues(new ArrayCollection(array(
+        $subProject1->setIssues(new ArrayCollection([
             new Issue('Issue #1', 'Issue #1 on Sub Project #1'),
-            new Issue('Issue #2', 'Issue #2 on Sub Project #1')
-        )));
+            new Issue('Issue #2', 'Issue #2 on Sub Project #1'),
+        ]));
 
-        $subProject2->setIssues(new ArrayCollection(array(
+        $subProject2->setIssues(new ArrayCollection([
             new Issue('Issue #1', 'Issue #1 on Sub Project #2'),
-            new Issue('Issue #2', 'Issue #2 on Sub Project #2')
-        )));
+            new Issue('Issue #2', 'Issue #2 on Sub Project #2'),
+        ]));
 
         $subProjects->add($subProject1);
         $subProjects->add($subProject2);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencePrimerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencePrimerTest.php
index 46a086e169..745dacc1c5 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencePrimerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencePrimerTest.php
@@ -1,15 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Proxy\Proxy;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Account;
 use Documents\Agent;
 use Documents\BlogPost;
 use Documents\Comment;
+use Documents\Ecommerce\ConfigurableProduct;
+use Documents\Ecommerce\Currency;
+use Documents\Ecommerce\Money;
+use Documents\Ecommerce\Option;
+use Documents\Ecommerce\StockItem;
 use Documents\Functional\EmbeddedWhichReferences;
 use Documents\Functional\EmbedNamed;
 use Documents\Functional\FavoritesUser;
@@ -21,14 +29,10 @@
 use Documents\ReferenceUser;
 use Documents\SimpleReferenceUser;
 use Documents\User;
-use Documents\Ecommerce\ConfigurableProduct;
-use Documents\Ecommerce\Currency;
-use Documents\Ecommerce\Money;
-use Documents\Ecommerce\Option;
-use Documents\Ecommerce\StockItem;
 use MongoDB\Driver\ReadPreference;
+use function func_get_args;
 
-class ReferencePrimerTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferencePrimerTest extends BaseTest
 {
     /**
      * @expectedException InvalidArgumentException
@@ -381,7 +385,7 @@ public function testPrimeReferencesIgnoresInitializedProxyObjects()
         $this->dm->createQueryBuilder(Group::class)->getQuery()->toArray();
 
         $invoked = 0;
-        $primer = function(DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$invoked) {
+        $primer = function (DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$invoked) {
             $invoked++;
         };
 
@@ -418,8 +422,8 @@ public function testPrimeReferencesInvokesPrimer()
         $this->dm->flush();
         $this->dm->clear();
 
-        $invokedArgs = array();
-        $primer = function(DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$invokedArgs) {
+        $invokedArgs = [];
+        $primer = function (DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$invokedArgs) {
             $invokedArgs[] = func_get_args();
         };
 
@@ -435,8 +439,8 @@ public function testPrimeReferencesInvokesPrimer()
         $this->assertArrayHasKey(Query::HINT_READ_PREFERENCE, $invokedArgs[0][3], 'Primer was invoked with UnitOfWork hints from original query.');
         $this->assertSame($readPreference, $invokedArgs[0][3][Query::HINT_READ_PREFERENCE], 'Primer was invoked with UnitOfWork hints from original query.');
 
-        $accountIds = array($account->getId());
-        $groupIds = array($group1->getId(), $group2->getId());
+        $accountIds = [$account->getId()];
+        $groupIds = [$group1->getId(), $group2->getId()];
 
         $this->assertEquals($accountIds, $invokedArgs[0][2]);
         $this->assertEquals($groupIds, $invokedArgs[1][2]);
@@ -474,7 +478,7 @@ public function testPrimeEmbeddedReferenceOneLevelDeep()
     {
         $user1 = new User();
         $user2 = new User();
-        $phone = new Phonenumber('555-GET-THIS',$user2);
+        $phone = new Phonenumber('555-GET-THIS', $user2);
 
         $user1->addPhonenumber($phone);
         $user1->setUsername('SomeName');
@@ -505,16 +509,25 @@ public function testPrimeEmbeddedReferenceTwoLevelsDeep()
         $product = new ConfigurableProduct('Bundle');
 
         $product->addOption(
-            new Option('Lens1', new Money(75.00, new Currency('USD',1)),
-            new StockItem('Filter1', new Money(50.00, new Currency('USD',1)), 1))
+            new Option(
+                'Lens1',
+                new Money(75.00, new Currency('USD', 1)),
+                new StockItem('Filter1', new Money(50.00, new Currency('USD', 1)), 1)
+            )
         );
         $product->addOption(
-            new Option('Lens2', new Money(120.00, new Currency('USD',1)),
-            new StockItem('Filter2', new Money(100.00, new Currency('USD',1)), 1))
+            new Option(
+                'Lens2',
+                new Money(120.00, new Currency('USD', 1)),
+                new StockItem('Filter2', new Money(100.00, new Currency('USD', 1)), 1)
+            )
         );
         $product->addOption(
-            new Option('Lens3', new Money(180.00, new Currency('USD',1)),
-            new StockItem('Filter3', new Money(0.01, new Currency('USD',1)), 1))
+            new Option(
+                'Lens3',
+                new Money(180.00, new Currency('USD', 1)),
+                new StockItem('Filter3', new Money(0.01, new Currency('USD', 1)), 1)
+            )
         );
 
         $this->dm->persist($product);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceRepositoryMethodTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceRepositoryMethodTest.php
index 659bc9aacf..c3345a49ce 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceRepositoryMethodTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferenceRepositoryMethodTest.php
@@ -1,11 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\BlogPost;
+use Documents\Comment;
 use Documents\User;
+use function strtotime;
 
-class ReferenceRepositoryMethodTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferenceRepositoryMethodTest extends BaseTest
 {
     public function testOneToOne()
     {
@@ -15,9 +20,9 @@ public function testOneToOne()
         $date2 = new \DateTime();
         $date2->setTimestamp(strtotime('-10 seconds'));
 
-        $blogPost = new \Documents\BlogPost('Test');
-        $blogPost->addComment(new \Documents\Comment('Comment 1', $date1));
-        $blogPost->addComment(new \Documents\Comment('Comment 2', $date2));
+        $blogPost = new BlogPost('Test');
+        $blogPost->addComment(new Comment('Comment 1', $date1));
+        $blogPost->addComment(new Comment('Comment 2', $date2));
         $this->dm->persist($blogPost);
         $this->dm->flush();
         $this->dm->clear();
@@ -70,9 +75,9 @@ public function testSetStrategy()
     {
         $repo = $this->dm->getRepository('Documents\BlogPost');
 
-        $blogPost = new \Documents\BlogPost('Test');
+        $blogPost = new BlogPost('Test');
 
-        $blogPost->addComment(new \Documents\Comment('Comment', new \DateTime()));
+        $blogPost->addComment(new Comment('Comment', new \DateTime()));
         $this->dm->persist($blogPost);
         $this->dm->flush();
         $this->dm->clear();
@@ -85,9 +90,9 @@ public function testSetStrategy()
 
     public function testRepositoryMethodWithoutMappedBy()
     {
-        $blogPost = new \Documents\BlogPost('Test');
+        $blogPost = new BlogPost('Test');
 
-        $blogPost->addComment(new \Documents\Comment('Comment', new \DateTime()));
+        $blogPost->addComment(new Comment('Comment', new \DateTime()));
         $this->dm->persist($blogPost);
         $this->dm->flush();
         $this->dm->clear();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
index 0abbfad029..30a2f4eb7d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
@@ -1,24 +1,31 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\Common\Persistence\Proxy;
 use Doctrine\ODM\MongoDB\Event\DocumentNotFoundEventArgs;
 use Doctrine\ODM\MongoDB\Events;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\PersistentCollection;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Account;
 use Documents\Address;
+use Documents\Group;
+use Documents\Phonenumber;
 use Documents\Profile;
 use Documents\ProfileNotify;
-use Documents\Phonenumber;
-use Documents\Account;
-use Documents\Group;
 use Documents\User;
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-use Doctrine\ODM\MongoDB\PersistentCollection;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\ObjectId;
+use function get_class;
 
-class ReferencesTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ReferencesTest extends BaseTest
 {
     public function testManyDeleteReference()
     {
-        $user = new \Documents\User();
+        $user = new User();
 
         $user->addGroup(new Group('Group 1'));
         $user->addGroup(new Group('Group 2'));
@@ -86,7 +93,7 @@ public function testLazyLoadedWithNotifyPropertyChanged()
         $this->dm->clear();
 
         $user = $this->dm->find(get_class($user), $user->getId());
-        $this->assertInstanceOf(\Doctrine\Common\Persistence\Proxy::class, $user->getProfileNotify());
+        $this->assertInstanceOf(Proxy::class, $user->getProfileNotify());
         $this->assertFalse($user->getProfileNotify()->__isInitialized());
 
         $user->getProfileNotify()->setLastName('Malarz');
@@ -126,7 +133,7 @@ public function testOneEmbedded()
 
     public function testManyEmbedded()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->addPhonenumber(new Phonenumber('6155139185'));
         $user->addPhonenumber(new Phonenumber('6153303769'));
 
@@ -166,7 +173,7 @@ public function testOneReference()
 
     public function testManyReference()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->addGroup(new Group('Group 1'));
         $user->addGroup(new Group('Group 2'));
 
@@ -263,7 +270,7 @@ public function testFlushInitializesNotEmptyPersistentCollection()
 
     public function testManyReferenceWithAddToSetStrategy()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->addUniqueGroup($group1 = new Group('Group 1'));
         $user->addUniqueGroup($group1);
         $user->addUniqueGroup(new Group('Group 2'));
@@ -319,7 +326,7 @@ public function testManyReferenceWithAddToSetStrategy()
 
     public function testSortReferenceManyOwningSide()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->addGroup(new Group('Group 1'));
         $user->addGroup(new Group('Group 2'));
 
@@ -350,7 +357,7 @@ public function testDocumentNotFoundExceptionWithArrayId()
     {
         $test = new DocumentWithArrayReference();
         $test->referenceOne = new DocumentWithArrayId();
-        $test->referenceOne->id = array('identifier' => 1);
+        $test->referenceOne->id = ['identifier' => 1];
 
         $this->dm->persist($test);
         $this->dm->persist($test->referenceOne);
@@ -360,10 +367,12 @@ public function testDocumentNotFoundExceptionWithArrayId()
         $collection = $this->dm->getDocumentCollection(get_class($test));
 
         $collection->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($test->id)),
-            array('$set' => array(
-                'referenceOne.$id' => array('identifier' => 2),
-            ))
+            ['_id' => new ObjectId($test->id)],
+            [
+            '$set' => [
+                'referenceOne.$id' => ['identifier' => 2],
+            ],
+            ]
         );
 
         $test = $this->dm->find(get_class($test), $test->id);
@@ -387,13 +396,13 @@ public function testDocumentNotFoundExceptionWithObjectId()
 
         $collection = $this->dm->getDocumentCollection(get_class($user));
 
-        $invalidId = new \MongoDB\BSON\ObjectId('abcdefabcdefabcdefabcdef');
+        $invalidId = new ObjectId('abcdefabcdefabcdefabcdef');
 
         $collection->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($user->getId())),
-            array('$set' => array(
-                'profile.$id' => $invalidId,
-            ))
+            ['_id' => new ObjectId($user->getId())],
+            [
+            '$set' => ['profile.$id' => $invalidId],
+            ]
         );
 
         $user = $this->dm->find(get_class($user), $user->getId());
@@ -418,13 +427,13 @@ public function testDocumentNotFoundExceptionWithMongoBinDataId()
 
         $collection = $this->dm->getDocumentCollection(get_class($test));
 
-        $invalidBinData = new \MongoDB\BSON\Binary('testbindata', \MongoDB\BSON\Binary::TYPE_OLD_BINARY);
+        $invalidBinData = new Binary('testbindata', Binary::TYPE_OLD_BINARY);
 
         $collection->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($test->id)),
-            array('$set' => array(
-                'referenceOne.$id' => $invalidBinData,
-            ))
+            ['_id' => new ObjectId($test->id)],
+            [
+            '$set' => ['referenceOne.$id' => $invalidBinData],
+            ]
         );
 
         $test = $this->dm->find(get_class($test), $test->id);
@@ -444,13 +453,13 @@ public function testDocumentNotFoundEvent()
 
         $collection = $this->dm->getDocumentCollection(get_class($user));
 
-        $invalidId = new \MongoDB\BSON\ObjectId('abcdefabcdefabcdefabcdef');
+        $invalidId = new ObjectId('abcdefabcdefabcdefabcdef');
 
         $collection->updateOne(
-            array('_id' => new \MongoDB\BSON\ObjectId($user->getId())),
-            array('$set' => array(
-                'profile.$id' => $invalidId,
-            ))
+            ['_id' => new ObjectId($user->getId())],
+            [
+            '$set' => ['profile.$id' => $invalidId],
+            ]
         );
 
         $user = $this->dm->find(get_class($user), $user->getId());
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RemoveTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RemoveTest.php
index 88ebb1f91c..4cc9841c17 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RemoveTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RemoveTest.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Account;
 use Documents\BlogPost;
 use Documents\CmsArticle;
@@ -12,7 +15,7 @@
 use Documents\Project;
 use Documents\User;
 
-class RemoveTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class RemoveTest extends BaseTest
 {
     public function testRemove()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RepositoriesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RepositoriesTest.php
index 8c9a3f0d85..64e5d6165d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/RepositoriesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/RepositoriesTest.php
@@ -1,14 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\Common\Collections\Criteria;
-use Documents\Account;
-use Documents\Address;
-use Documents\Phonenumber;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
 
-class RepositoriesTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class RepositoriesTest extends BaseTest
 {
     public function setUp()
     {
@@ -36,7 +36,7 @@ public function testFind()
         $user2 = $this->repository->find($this->user->getId());
         $this->assertSame($this->user, $user2);
 
-        $user3 = $this->repository->findOneBy(array('username' => 'w00ting'));
+        $user3 = $this->repository->findOneBy(['username' => 'w00ting']);
         $this->assertSame($user2, $user3);
     }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ShardKeyTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ShardKeyTest.php
index 985f58f442..711b60851b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ShardKeyTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ShardKeyTest.php
@@ -1,11 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
-use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Tests\QueryLogger;
 use Documents\Sharded\ShardedOne;
+use MongoDB\BSON\ObjectId;
+use function array_keys;
+use function end;
+use function get_class;
 
 class ShardKeyTest extends BaseTest
 {
@@ -17,7 +22,7 @@ class ShardKeyTest extends BaseTest
     protected function getConfiguration()
     {
         $this->markTestSkipped('mongodb-driver: query logging does not exist');
-        if ( ! isset($this->ql)) {
+        if (! isset($this->ql)) {
             $this->ql = new QueryLogger();
         }
 
@@ -31,7 +36,7 @@ public function setUp()
     {
         parent::setUp();
 
-        $class = \Documents\Sharded\ShardedOne::class;
+        $class = ShardedOne::class;
         $this->skipTestIfNotSharded($class);
         $schemaManager = $this->dm->getSchemaManager();
         $schemaManager->ensureDocumentSharding($class);
@@ -43,7 +48,7 @@ public function testUpdateAfterSave()
         $this->dm->persist($o);
         $this->dm->flush();
 
-        /** @var \Documents\Sharded\ShardedOne $o */
+        /** @var ShardedOne $o */
         $o = $this->dm->find(get_class($o), $o->id);
         $o->title = 'test2';
         $this->dm->flush();
@@ -58,7 +63,7 @@ public function testUpdateAfterSave()
     public function testUpsert()
     {
         $o = new ShardedOne();
-        $o->id = new \MongoDB\BSON\ObjectId();
+        $o->id = new ObjectId();
         $this->dm->persist($o);
         $this->dm->flush();
 
@@ -121,6 +126,6 @@ public function testUpdateWithUpsertTrue()
         $this->dm->flush();
 
         $o->key = 'testing2';
-        $this->dm->flush(null, array('upsert' => true));
+        $this->dm->flush(null, ['upsert' => true]);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleReferencesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleReferencesTest.php
index 79fe0b7edc..f7302789d7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleReferencesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleReferencesTest.php
@@ -1,10 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\SimpleReferenceUser;
 use Documents\User;
+use MongoDB\BSON\ObjectId;
+use function current;
+use function end;
 
 class SimpleReferencesTest extends BaseTest
 {
@@ -31,41 +36,41 @@ public function setUp()
     public function testIndexes()
     {
         $indexes = $this->dm->getSchemaManager()->getDocumentIndexes('Documents\SimpleReferenceUser');
-        $this->assertEquals(array('userId' => 1), $indexes[0]['keys']);
+        $this->assertEquals(['userId' => 1], $indexes[0]['keys']);
     }
 
     public function testStorage()
     {
         $test = $this->dm->getDocumentCollection('Documents\SimpleReferenceUser')->findOne();
         $this->assertNotNull($test);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $test['userId']);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $test['users'][0]);
+        $this->assertInstanceOf(ObjectId::class, $test['userId']);
+        $this->assertInstanceOf(ObjectId::class, $test['users'][0]);
     }
 
     public function testQuery()
     {
-        $this->user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jwage'));
+        $this->user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jwage']);
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->references($this->user);
-        $this->assertEquals(array('userId' => new \MongoDB\BSON\ObjectId($this->user->getId())), $qb->getQuery()->debug('query'));
+        $this->assertEquals(['userId' => new ObjectId($this->user->getId())], $qb->getQuery()->debug('query'));
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->equals($this->user->getId());
-        $this->assertEquals(array('userId' => new \MongoDB\BSON\ObjectId($this->user->getId())), $qb->getQuery()->debug('query'));
+        $this->assertEquals(['userId' => new ObjectId($this->user->getId())], $qb->getQuery()->debug('query'));
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
-        $qb->field('user')->in(array($this->user->getId()));
-        $this->assertEquals(array('userId' => array('$in' => array(new \MongoDB\BSON\ObjectId($this->user->getId())))), $qb->getQuery()->debug('query'));
+        $qb->field('user')->in([$this->user->getId()]);
+        $this->assertEquals(['userId' => ['$in' => [new ObjectId($this->user->getId())]]], $qb->getQuery()->debug('query'));
     }
 
     public function testProxy()
     {
-        $this->user = $this->dm->getRepository('Documents\User')->findOneBy(array('username' => 'jwage'));
+        $this->user = $this->dm->getRepository('Documents\User')->findOneBy(['username' => 'jwage']);
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->references($this->user);
-        $this->assertEquals(array('userId' => new \MongoDB\BSON\ObjectId($this->user->getId())), $qb->getQuery()->debug('query'));
+        $this->assertEquals(['userId' => new ObjectId($this->user->getId())], $qb->getQuery()->debug('query'));
 
         $this->dm->clear();
 
@@ -81,7 +86,7 @@ public function testProxy()
 
     public function testPersistentCollectionOwningSide()
     {
-        $test = $this->dm->getRepository('Documents\SimpleReferenceUser')->findOneBy(array());
+        $test = $this->dm->getRepository('Documents\SimpleReferenceUser')->findOneBy([]);
         $users = $test->getUsers()->toArray();
         $this->assertEquals(2, $test->getUsers()->count());
         $this->assertEquals('jwage', current($users)->getUsername());
@@ -90,40 +95,41 @@ public function testPersistentCollectionOwningSide()
 
     public function testPersistentCollectionInverseSide()
     {
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array());
+        $user = $this->dm->getRepository('Documents\User')->findOneBy([]);
         $test = $user->getSimpleReferenceManyInverse()->toArray();
-        $this->assertEquals('test' ,current($test)->getName());
+        $this->assertEquals('test', current($test)->getName());
     }
 
     public function testOneInverseSide()
     {
-        $user = $this->dm->getRepository('Documents\User')->findOneBy(array());
+        $user = $this->dm->getRepository('Documents\User')->findOneBy([]);
         $test = $user->getSimpleReferenceOneInverse();
         $this->assertEquals('test', $test->getName());
     }
 
-    public function testQueryForNonIds() {
+    public function testQueryForNonIds()
+    {
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->equals(null);
-        $this->assertEquals(array('userId' => null), $qb->getQueryArray());
+        $this->assertEquals(['userId' => null], $qb->getQueryArray());
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->notEqual(null);
-        $this->assertEquals(array('userId' => array('$ne' => null)), $qb->getQueryArray());
+        $this->assertEquals(['userId' => ['$ne' => null]], $qb->getQueryArray());
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('user')->exists(true);
-        $this->assertEquals(array('userId' => array('$exists' => true)), $qb->getQueryArray());
+        $this->assertEquals(['userId' => ['$exists' => true]], $qb->getQueryArray());
     }
 
     public function testRemoveDocumentByEmptyRefMany()
     {
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
-        $qb->field('users')->equals(array());
-        $this->assertEquals(array('users' => array()), $qb->getQueryArray());
+        $qb->field('users')->equals([]);
+        $this->assertEquals(['users' => []], $qb->getQueryArray());
 
         $qb = $this->dm->createQueryBuilder('Documents\SimpleReferenceUser');
         $qb->field('users')->equals(new \stdClass());
-        $this->assertEquals(array('users' => new \stdClass()), $qb->getQueryArray());
+        $this->assertEquals(['users' => new \stdClass()], $qb->getQueryArray());
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleTest.php
index 042e3a1b29..8f88b63a38 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SimpleTest.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Bars\Bar;
 use Documents\Bars\Location;
 
-class SimpleTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class SimpleTest extends BaseTest
 {
     public function testSimple()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SplObjectHashCollisionsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SplObjectHashCollisionsTest.php
index 2951158328..26532cccf4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/SplObjectHashCollisionsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/SplObjectHashCollisionsTest.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
 class SplObjectHashCollisionsTest extends BaseTest
 {
@@ -48,11 +51,23 @@ public function testParentAssociationsLeftover($f, $leftover)
 
     public function provideParentAssociationsIsCleared()
     {
-        return array(
-            array( function (DocumentManager $dm) { $dm->clear(); }, 0 ),
-            array( function (DocumentManager $dm, $doc) { $dm->clear(get_class($doc)); }, 1 ),
-            array( function (DocumentManager $dm, $doc) { $dm->detach($doc); }, 1 ),
-        );
+        return [
+            [
+        function (DocumentManager $dm) {
+                $dm->clear();
+        }, 0,
+            ],
+            [
+            function (DocumentManager $dm, $doc) {
+                $dm->clear(get_class($doc));
+            }, 1,
+            ],
+            [
+            function (DocumentManager $dm, $doc) {
+                $dm->detach($doc);
+            }, 1,
+            ],
+        ];
     }
 
     private function expectCount($prop, $expected)
@@ -77,7 +92,7 @@ class SplColDoc
     public $one;
 
     /** @ODM\EmbedMany */
-    public $many = array();
+    public $many = [];
 }
 
 /** @ODM\EmbeddedDocument */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/TestTargetDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/TestTargetDocument.php
index 7bd43c891e..9755f27a61 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/TestTargetDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/TestTargetDocument.php
@@ -1,34 +1,37 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class TargetDocumentTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class TargetDocumentTest extends BaseTest
 {
     public function testMappedSuperClassAsTargetDocument()
     {
-    	$test = new TargetDocumentTestDocument();
-    	$test->reference = new TargetDocumentTestReference();
-    	$this->dm->persist($test);
-    	$this->dm->persist($test->reference);
-    	$this->dm->flush();
+        $test = new TargetDocumentTestDocument();
+        $test->reference = new TargetDocumentTestReference();
+        $this->dm->persist($test);
+        $this->dm->persist($test->reference);
+        $this->dm->flush();
     }
 }
 
 /** @ODM\Document */
 class TargetDocumentTestDocument
 {
-	/** @ODM\Id */
-	public $id;
+    /** @ODM\Id */
+    public $id;
 
-	/** @ODM\ReferenceOne(targetDocument="Doctrine\ODM\MongoDB\Tests\Functional\TargetDocumentTestReference") */
-	public $reference;
+    /** @ODM\ReferenceOne(targetDocument="Doctrine\ODM\MongoDB\Tests\Functional\TargetDocumentTestReference") */
+    public $reference;
 }
 
 /** @ODM\MappedSuperclass */
 abstract class TargetDocumentTestReference
 {
-	/** @ODM\Id */
-	public $id;
-}
\ No newline at end of file
+    /** @ODM\Id */
+    public $id;
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1011Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1011Test.php
index 98dbf6ac20..f3e70c2f8d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1011Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1011Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1011Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1011Test extends BaseTest
 {
     public function testClearCollection()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1017Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1017Test.php
index 4a91714ee6..a3908bfedc 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1017Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1017Test.php
@@ -1,16 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\UnitOfWork;
+use function in_array;
+use function spl_object_hash;
 
 class GH1017Test extends BaseTest
 {
     public function testSPLObjectHashCollisionOnReplacingEmbeddedDoc()
     {
-        $usedHashes = array();
+        $usedHashes = [];
         $owner = new GH1017Document();
         $this->dm->persist($owner);
         $this->dm->flush();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
index 014bf9799b..85abcf9a8d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
@@ -1,11 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 use Doctrine\ODM\MongoDB\Events;
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
+use function array_merge;
+use function get_class;
 
 class GH1058Test extends BaseTest
 {
@@ -14,7 +19,7 @@ class GH1058Test extends BaseTest
      */
     public function testModifyingDuringOnFlushEventNewDocument()
     {
-        $this->dm->getEventManager()->addEventListener(array(Events::onFlush), new GH1058Listener());
+        $this->dm->getEventManager()->addEventListener([Events::onFlush], new GH1058Listener());
         $document = new GH1058PersistDocument();
         $document->setValue('value 1');
         $this->dm->persist($document);
@@ -26,7 +31,7 @@ public function testModifyingDuringOnFlushEventNewDocument()
      */
     public function testModifyingDuringOnFlushEventNewDocumentWithId()
     {
-        $this->dm->getEventManager()->addEventListener(array(Events::onFlush), new GH1058Listener());
+        $this->dm->getEventManager()->addEventListener([Events::onFlush], new GH1058Listener());
         $document = new GH1058UpsertDocument();
         $document->generateId();
         $document->setValue('value 1');
@@ -37,7 +42,8 @@ public function testModifyingDuringOnFlushEventNewDocumentWithId()
 
 class GH1058Listener
 {
-    public function onFlush(OnFlushEventArgs $args) {
+    public function onFlush(OnFlushEventArgs $args)
+    {
         $dm = $args->getDocumentManager();
         $uow = $dm->getUnitOfWork();
 
@@ -87,10 +93,10 @@ public function getId()
         return $this->id;
     }
 
-    public final function generateId()
+    final public function generateId()
     {
-        if (!isset($this->id)) {
-            $this->id = (string) new \MongoDB\BSON\ObjectId();
+        if (! isset($this->id)) {
+            $this->id = (string) new ObjectId();
         }
     }
 
@@ -99,4 +105,3 @@ public function setValue($value)
         $this->value = $value;
     }
 }
-
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1107Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1107Test.php
index 5a44dd3a98..fa270d522f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1107Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1107Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Persisters;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1117Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1117Test.php
index 49f36ca9e8..25f548a8e8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1117Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1117Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH1117Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1117Test extends BaseTest
 {
     public function testAddOnUninitializedCollection()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1132Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1132Test.php
index b4199b4a54..3a5e642876 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1132Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1132Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Phonenumber;
 use Documents\User;
+use function get_class;
 
-class GH1132Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1132Test extends BaseTest
 {
     public function testClonedPersistentCollectionCanBeClearedAndUsedInNewDocument()
     {
@@ -36,7 +40,7 @@ public function testClonedPersistentCollectionCanBeClearedAndUsedInManagedDocume
         $this->dm->persist($u);
         $this->dm->persist($u2);
         $this->dm->flush();
-        
+
         $u2->setPhonenumbers(clone $u->getPhonenumbers());
         $u2->getPhonenumbers()->clear();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1138Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1138Test.php
index e4f9a99b5b..46367606f2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1138Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1138Test.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
+use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Tests\QueryLogger;
 
-class GH1138Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1138Test extends BaseTest
 {
     /**
      * @var Doctrine\ODM\MongoDB\Tests\QueryLogger
@@ -17,7 +20,7 @@ class GH1138Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
     protected function getConfiguration()
     {
         $this->markTestSkipped('mongodb-driver: query logging does not exist');
-        if ( ! isset($this->ql)) {
+        if (! isset($this->ql)) {
             $this->ql = new QueryLogger();
         }
 
@@ -48,7 +51,7 @@ public function testUpdatingDocumentBeforeItsInsertionShouldNotEntailMultipleQue
 /** @ODM\Document */
 class GH1138Document
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -81,4 +84,3 @@ public function onFlush(OnFlushEventArgs $args)
         }
     }
 }
-
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1152Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1152Test.php
index 74411940fe..36b3349640 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1152Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1152Test.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\LifecycleEventArgs;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1152Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1152Test extends BaseTest
 {
     public function testParentAssociationsInPostLoad()
     {
@@ -34,7 +37,7 @@ public function testParentAssociationsInPostLoad()
 /** @ODM\Document */
 class GH1152Parent
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -56,7 +59,7 @@ public function postLoad(LifecycleEventArgs $args)
         $dm = $args->getDocumentManager();
         $document = $args->getDocument();
 
-        if (!$document instanceof GH1152Child) {
+        if (! $document instanceof GH1152Child) {
             return;
         }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1225Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1225Test.php
index bf74f86f71..9e743e8723 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1225Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1225Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH1225Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1225Test extends BaseTest
 {
     public function testRemoveAddEmbeddedDocToExistingDocumentWithPreUpdateHook()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1229Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1229Test.php
index ebc5b3a633..09c9227534 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1229Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1229Test.php
@@ -1,11 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function count;
+use function end;
 
-class GH1229Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1229Test extends BaseTest
 {
     /**
      * @var string
@@ -134,7 +139,7 @@ public function testMethodAWithClone()
 /** @ODM\Document */
 class GH1229Parent
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -155,18 +160,12 @@ public function getChildren()
         return $this->children->toArray();
     }
 
-    /**
-     * @param GH1229Child $child
-     */
     public function addChild(GH1229Child $child)
     {
         $child->setOrder(count($this->children));
         $this->children->add($child);
     }
 
-    /**
-     * @param GH1229Child $child
-     */
     public function removeChild(GH1229Child $child)
     {
         $this->children->removeElement($child);
@@ -190,7 +189,7 @@ public function reorderChildren($starting, $change)
 /** @ODM\EmbeddedDocument */
 class GH1229Child
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Field(type="string") */
     public $name;
@@ -230,5 +229,5 @@ public function setOrder($order)
 /** @ODM\EmbeddedDocument */
 class GH1229ChildTypeB extends GH1229Child
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1232Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1232Test.php
index 8bf47267b2..cf9ef59718 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1232Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1232Test.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\DocumentRepository;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1232Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1232Test extends BaseTest
 {
     /**
      * @doesNotPerformAssertions
@@ -32,7 +35,7 @@ public function testRemoveDoesNotCauseErrors()
 /** @ODM\Document */
 class GH1232Post
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1275Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1275Test.php
index 39e8447630..675b8fdf64 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1275Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1275Test.php
@@ -1,12 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function array_map;
 
-class GH1275Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1275Test extends BaseTest
 {
     public function testResortAtomicCollectionsFlipItems()
     {
@@ -32,7 +36,7 @@ public function testResortAtomicCollectionsFlipItems()
         $container->add($itemThree);
 
         $this->assertSame(
-            array('Number One', 'Number Two', 'Number Three'),
+            ['Number One', 'Number Two', 'Number Three'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -44,7 +48,7 @@ public function testResortAtomicCollectionsFlipItems()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number One','Number Three', 'Number Two'),
+            ['Number One','Number Three', 'Number Two'],
             array_map($getNameCallback, $container->items->toArray())
         );
     }
@@ -73,7 +77,7 @@ public function testResortAtomicCollections()
         $container->add($itemThree);
 
         $this->assertSame(
-            array('Number One', 'Number Two', 'Number Three'),
+            ['Number One', 'Number Two', 'Number Three'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -83,7 +87,7 @@ public function testResortAtomicCollections()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number One', 'Number Two', 'Number Three'),
+            ['Number One', 'Number Two', 'Number Three'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -93,7 +97,7 @@ public function testResortAtomicCollections()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number Two', 'Number One', 'Number Three'),
+            ['Number Two', 'Number One', 'Number Three'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -103,7 +107,7 @@ public function testResortAtomicCollections()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number One', 'Number Three', 'Number Two'),
+            ['Number One', 'Number Three', 'Number Two'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -113,7 +117,7 @@ public function testResortAtomicCollections()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number One', 'Number Three', 'Number Two'),
+            ['Number One', 'Number Three', 'Number Two'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -123,7 +127,7 @@ public function testResortAtomicCollections()
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('Number Three', 'Number One', 'Number Two'),
+            ['Number Three', 'Number One', 'Number Two'],
             array_map($getNameCallback, $container->items->toArray())
         );
 
@@ -132,14 +136,14 @@ public function testResortAtomicCollections()
 
     public static function getCollectionStrategies()
     {
-        return array(
-            'testResortWithStrategyAddToSet' => array(ClassMetadata::STORAGE_STRATEGY_ADD_TO_SET),
-            'testResortWithStrategySet' => array(ClassMetadata::STORAGE_STRATEGY_SET),
-            'testResortWithStrategySetArray' => array(ClassMetadata::STORAGE_STRATEGY_SET_ARRAY),
-            'testResortWithStrategyPushAll' => array(ClassMetadata::STORAGE_STRATEGY_PUSH_ALL),
-            'testResortWithStrategyAtomicSet' => array(ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET),
-            'testResortWithStrategyAtomicSetArray' => array(ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY),
-        );
+        return [
+            'testResortWithStrategyAddToSet' => [ClassMetadata::STORAGE_STRATEGY_ADD_TO_SET],
+            'testResortWithStrategySet' => [ClassMetadata::STORAGE_STRATEGY_SET],
+            'testResortWithStrategySetArray' => [ClassMetadata::STORAGE_STRATEGY_SET_ARRAY],
+            'testResortWithStrategyPushAll' => [ClassMetadata::STORAGE_STRATEGY_PUSH_ALL],
+            'testResortWithStrategyAtomicSet' => [ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET],
+            'testResortWithStrategyAtomicSetArray' => [ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET_ARRAY],
+        ];
     }
 
     /**
@@ -161,7 +165,7 @@ public function testResortEmbedManyCollection($strategy)
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('one', 'two', 'three'),
+            ['one', 'two', 'three'],
             array_map($getNameCallback, $container->$strategy->toArray())
         );
 
@@ -175,7 +179,7 @@ public function testResortEmbedManyCollection($strategy)
         $this->dm->refresh($container);
 
         $this->assertSame(
-            array('one', 'three', 'two'),
+            ['one', 'three', 'two'],
             array_map($getNameCallback, $container->$strategy->toArray())
         );
     }
@@ -184,7 +188,8 @@ public function testResortEmbedManyCollection($strategy)
 /**
  * @ODM\Document(collection="item")
  */
-class Item {
+class Item
+{
     /** @ODM\Id */
     public $id;
 
@@ -206,7 +211,8 @@ public function __construct(Container $c, $name)
 /**
  * @ODM\EmbeddedDocument
  */
-class Element {
+class Element
+{
     /** @ODM\Id */
     public $id;
 
@@ -222,17 +228,18 @@ public function __construct($name)
 /**
  * @ODM\Document(collection="container")
  */
-class Container {
+class Container
+{
     /** @ODM\Id */
     public $id;
 
     /** @ODM\ReferenceMany(
-    *     targetDocument="Item",
-    *     cascade={"refresh","persist"},
-    *     orphanRemoval="true",
-    *     strategy="atomicSet"
-    * )
-    */
+     *     targetDocument="Item",
+     *     cascade={"refresh","persist"},
+     *     orphanRemoval="true",
+     *     strategy="atomicSet"
+     * )
+     */
     public $items;
 
     /**
@@ -305,7 +312,7 @@ public function __construct()
     public function add(Item $item)
     {
         $this->items->add($item);
-        if ($this->items->count() == 1) {
+        if ($this->items->count() === 1) {
             $this->firstItem = $item;
         }
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1294Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1294Test.php
index 310886819a..b42f86680d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1294Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1294Test.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\Regex;
 
-class GH1294Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1294Test extends BaseTest
 {
     public function testRegexSearchOnIdentifierWithUuidStrategy()
     {
@@ -26,10 +30,10 @@ public function testRegexSearchOnIdentifierWithUuidStrategy()
         $qb = $this->dm->createQueryBuilder($userClass);
 
         $res = $qb->field('id')
-            ->equals(new \MongoDB\BSON\Regex("^bbb.*$", 'i'))
+            ->equals(new Regex('^bbb.*$', 'i'))
             ->getQueryArray();
 
-        $this->assertInstanceOf(\MongoDB\BSON\Regex::class, $res['_id']);
+        $this->assertInstanceOf(Regex::class, $res['_id']);
         $this->assertEquals('^bbb.*$', $res['_id']->getPattern());
         $this->assertEquals('i', $res['_id']->getFlags());
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1346Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1346Test.php
index 2ddcf51050..a9acd170d2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1346Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1346Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1346Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1346Test extends BaseTest
 {
     /**
      * @group GH1346Test
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1418Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1418Test.php
index e399459357..b048d022e2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1418Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1418Test.php
@@ -1,23 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1418Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1418Test extends BaseTest
 {
     public function testManualHydrateAndMerge()
     {
-        $document = new GH1418Document;
-        $this->dm->getHydratorFactory()->hydrate($document, array(
+        $document = new GH1418Document();
+        $this->dm->getHydratorFactory()->hydrate($document, [
           '_id' => 1,
           'name' => 'maciej',
           'embedOne' => ['name' => 'maciej', 'sourceId' => 1],
           'embedMany' => [
-              ['name' => 'maciej', 'sourceId' => 2]
+              ['name' => 'maciej', 'sourceId' => 2],
           ],
-        ), [ Query::HINT_READ_ONLY => true ]);
+        ], [ Query::HINT_READ_ONLY => true ]);
 
         $this->assertEquals(1, $document->embedOne->id);
         $this->assertEquals(2, $document->embedMany->first()->id);
@@ -37,7 +40,7 @@ public function testManualHydrateAndMerge()
 
     public function testReadDocumentAndManage()
     {
-        $document = new GH1418Document;
+        $document = new GH1418Document();
         $document->id = 1;
 
         $embedded = new GH1418Embedded();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1428Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1428Test.php
index 7f8eab65a7..c66ee9b569 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1428Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1428Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1435Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1435Test.php
index 0d47dfc790..1a6c719f89 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1435Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1435Test.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\ObjectId;
 
 class GH1435Test extends BaseTest
 {
     public function testUpsert()
     {
-        $id = (string) new \MongoDB\BSON\ObjectId();
+        $id = (string) new ObjectId();
 
         $document = new GH1435Document();
         $document->id = $id;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1525Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1525Test.php
index 43b9ef47a6..0dedf9b8df 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1525Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1525Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Id\UuidGenerator;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH1525Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH1525Test extends BaseTest
 {
     public function testEmbedCloneTwoFlushesPerDocument()
     {
@@ -26,7 +30,7 @@ public function testEmbedCloneTwoFlushesPerDocument()
         $this->dm->clear();
 
         for ($i = 0; $i < 2; ++$i) {
-            $test = $this->dm->getRepository(GH1525Document::class)->findOneBy(array('name' => 'test' . $i));
+            $test = $this->dm->getRepository(GH1525Document::class)->findOneBy(['name' => 'test' . $i]);
 
             $this->assertInstanceOf(GH1525Document::class, $test);
 
@@ -41,7 +45,7 @@ public function testEmbedCloneTwoFlushesPerDocument()
 
     public function testEmbedCloneWithIdStrategyNoneOnParentAndEarlyPersist()
     {
-        $uuidGen = new \Doctrine\ODM\MongoDB\Id\UuidGenerator();
+        $uuidGen = new UuidGenerator();
         $embedded = new GH1525Embedded('embedded');
 
         $count = 2;
@@ -55,7 +59,7 @@ public function testEmbedCloneWithIdStrategyNoneOnParentAndEarlyPersist()
         $this->dm->clear();
 
         for ($i = 0; $i < $count; ++$i) {
-            $test = $this->dm->getRepository(GH1525DocumentIdStrategyNone::class)->findOneBy(array('name' => 'test' . $i));
+            $test = $this->dm->getRepository(GH1525DocumentIdStrategyNone::class)->findOneBy(['name' => 'test' . $i]);
 
             $this->assertInstanceOf(GH1525DocumentIdStrategyNone::class, $test);
 
@@ -66,7 +70,7 @@ public function testEmbedCloneWithIdStrategyNoneOnParentAndEarlyPersist()
 
     public function testEmbedCloneWithIdStrategyNoneOnParentAndLatePersist()
     {
-        $uuidGen = new \Doctrine\ODM\MongoDB\Id\UuidGenerator();
+        $uuidGen = new UuidGenerator();
         $embedded = new GH1525Embedded('embedded');
 
         $count = 2;
@@ -80,7 +84,7 @@ public function testEmbedCloneWithIdStrategyNoneOnParentAndLatePersist()
         $this->dm->clear();
 
         for ($i = 0; $i < $count; ++$i) {
-            $test = $this->dm->getRepository(GH1525DocumentIdStrategyNone::class)->findOneBy(array('name' => 'test' . $i));
+            $test = $this->dm->getRepository(GH1525DocumentIdStrategyNone::class)->findOneBy(['name' => 'test' . $i]);
 
             $this->assertInstanceOf(GH1525DocumentIdStrategyNone::class, $test);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1572Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1572Test.php
index bbe7f9ea6e..5f325cd1a4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1572Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1572Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH232Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH232Test.php
index 70aea19411..58cdcabf20 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH232Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH232Test.php
@@ -1,14 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-/**
- * @since 6/26/12
- */
-class GH232Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH232Test extends BaseTest
 {
     public function testReferencedDocumentInsideEmbeddedDocument()
     {
@@ -47,10 +47,10 @@ class Product
     public $name;
 
     /** @ODM\EmbedMany(targetDocument="Price") */
-    public $prices = array();
+    public $prices = [];
 
     /** @ODM\EmbedMany(targetDocument="SubProduct") */
-    public $subproducts = array();
+    public $subproducts = [];
 
     public function __construct($name)
     {
@@ -63,7 +63,7 @@ public function __construct($name)
 class SubProduct
 {
     /** @ODM\EmbedMany(targetDocument="Price") */
-    public $prices = array();
+    public $prices = [];
 
     public function __construct()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH245Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH245Test.php
index 73b0911d3b..3923e6cafd 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH245Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH245Test.php
@@ -1,46 +1,50 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH245Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH245Test extends BaseTest
 {
-	public function testTest()
-	{
-		$order = new GH245Order();
-		$order->id = 1;
+    public function testTest()
+    {
+        $order = new GH245Order();
+        $order->id = 1;
 
-		$orderLog = new GH245OrderLog();
-		$orderLog->order = $order;
+        $orderLog = new GH245OrderLog();
+        $orderLog->order = $order;
 
-		$this->dm->persist($orderLog);
-		$this->dm->persist($order);
-		$this->dm->flush();
-		$this->dm->clear();
+        $this->dm->persist($orderLog);
+        $this->dm->persist($order);
+        $this->dm->flush();
+        $this->dm->clear();
 
-		$user = $this->dm->find(get_class($order), $order->id);
+        $user = $this->dm->find(get_class($order), $order->id);
 
-		$this->assertInternalType('int', $order->id);
+        $this->assertInternalType('int', $order->id);
 
-		$check = $this->dm->getDocumentCollection(get_class($orderLog))->findOne();
-		$this->assertInternalType('int', $check['order']['$id']);
-	}
+        $check = $this->dm->getDocumentCollection(get_class($orderLog))->findOne();
+        $this->assertInternalType('int', $check['order']['$id']);
+    }
 }
 
 /** @ODM\Document */
 class GH245Order
 {
-	/** @ODM\Id(strategy="NONE") */
-	public $id;
+    /** @ODM\Id(strategy="NONE") */
+    public $id;
 }
 
 /** @ODM\Document */
 class GH245OrderLog
 {
-	/** @ODM\Id */
-	public $id;
+    /** @ODM\Id */
+    public $id;
 
-	/** @ODM\ReferenceOne(targetDocument="GH245Order") */
-	public $order;
+    /** @ODM\ReferenceOne(targetDocument="GH245Order") */
+    public $order;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
index 197f553608..7a3d999b4f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -58,7 +60,7 @@ public function testNestedReferences()
  * @ODM\Document(collection="users")
  */
 class GH267User
-{   
+{
     /** @ODM\Id */
     protected $id;
 
@@ -75,32 +77,32 @@ public function __construct($name)
         $this->name = $name;
     }
 
-    public function setId($id) 
+    public function setId($id)
     {
         $this->id = $id;
     }
 
-    public function getId() 
+    public function getId()
     {
         return $this->id;
     }
 
-    public function setName($name) 
+    public function setName($name)
     {
         $this->name = $name;
     }
 
-    public function getName() 
+    public function getName()
     {
         return $this->name;
     }
 
-    public function setCompany($company) 
+    public function setCompany($company)
     {
         $this->company = $company;
     }
 
-    public function getCompany() 
+    public function getCompany()
     {
         return $this->company;
     }
@@ -113,7 +115,7 @@ public function getCompany()
  * @ODM\DiscriminatorMap({"seller"="GH267SellerCompany", "buyer"="GH267BuyerCompany"})
  */
 class GH267Company
-{   
+{
     /** @ODM\Id */
     protected $id;
 
@@ -122,22 +124,22 @@ class GH267Company
      */
     protected $users;
 
-    public function setId($id) 
+    public function setId($id)
     {
         $this->id = $id;
     }
 
-    public function getId() 
+    public function getId()
     {
         return $this->id;
     }
 
-    public function setUsers($users) 
+    public function setUsers($users)
     {
         $this->users = $users;
     }
 
-    public function getUsers() 
+    public function getUsers()
     {
         return $this->users;
     }
@@ -147,14 +149,12 @@ public function getUsers()
  * @ODM\Document(collection="companies")
  */
 class GH267BuyerCompany extends GH267Company
-{   
-
+{
 }
 
 /**
  * @ODM\Document(collection="companies")
  */
 class GH267SellerCompany extends GH267Company
-{   
-
+{
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH385Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH385Test.php
index 1753843134..c7452dfc84 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH385Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH385Test.php
@@ -1,14 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\ObjectId;
 
 class GH385Test extends BaseTest
 {
     public function testQueryBuilderShouldPrepareUnmappedFields()
     {
-        $identifier = new \MongoDB\BSON\ObjectId();
+        $identifier = new ObjectId();
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->upsert()
@@ -19,11 +21,11 @@ public function testQueryBuilderShouldPrepareUnmappedFields()
 
         $debug = $qb->getQuery()->getQuery();
 
-        $this->assertEquals(array('$inc' => array('foo.bar.level3a' => 1, 'foo.bar.level3b' => 1)), $debug['newObj']);
+        $this->assertEquals(['$inc' => ['foo.bar.level3a' => 1, 'foo.bar.level3b' => 1]], $debug['newObj']);
 
         $qb->getQuery()->execute();
 
-        $check = $this->dm->getDocumentCollection('Documents\User')->findOne(array('_id' => $identifier));
+        $check = $this->dm->getDocumentCollection('Documents\User')->findOne(['_id' => $identifier]);
         $this->assertNotNull($check);
         $this->assertTrue(isset($check['foo']['bar']['level3a']));
         $this->assertTrue(isset($check['foo']['bar']['level3b']));
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH389Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH389Test.php
index fab9e4d63f..036e0e7109 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH389Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH389Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH389Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH389Test extends BaseTest
 {
     public function testDiscriminatorEmptyEmbeddedDocument()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH426Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH426Test.php
index 1f8545a8ad..f8f83b9078 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH426Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH426Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH426Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH426Test extends BaseTest
 {
     public function testTest()
     {
@@ -33,7 +36,7 @@ class GH426Form
     public $id;
 
     /** @ODM\ReferenceMany(targetDocument="GH426Field", mappedBy="form", cascade={"all"}) */
-    public $fields = array();
+    public $fields = [];
 
     /** @ODM\ReferenceOne(targetDocument="GH426Field", mappedBy="form", sort={"_id":1}) */
     public $firstField;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH435Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH435Test.php
index dcfe4c89fd..5808ecdffb 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH435Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH435Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH435Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH435Test extends BaseTest
 {
     public function testOverridingFieldsType()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH453Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH453Test.php
index fdebd98f91..9285c5acfd 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH453Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH453Test.php
@@ -1,15 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function array_values;
+use function get_class;
+use function sprintf;
 
-class GH453Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH453Test extends BaseTest
 {
     public function testHashWithStringKeys()
     {
-        $hash = array('a' => 'x', 'b' => 'y', 'c' => 'z');
+        $hash = ['a' => 'x', 'b' => 'y', 'c' => 'z'];
 
         $doc = new GH453Document();
         $doc->hash = $hash;
@@ -40,7 +46,7 @@ public function testHashWithStringKeys()
 
     public function testHashWithNumericKeys()
     {
-        $hash = array(0 => 'x', 1 => 'y', 2 => 'z');
+        $hash = [0 => 'x', 1 => 'y', 2 => 'z'];
 
         $doc = new GH453Document();
         $doc->hash = $hash;
@@ -71,7 +77,7 @@ public function testHashWithNumericKeys()
 
     public function testCollection()
     {
-        $col = array('x', 'y', 'z');
+        $col = ['x', 'y', 'z'];
 
         $doc = new GH453Document();
         $doc->colPush = $col;
@@ -107,14 +113,20 @@ public function testCollection()
 
     public function testEmbedMany()
     {
-        $colPush = new ArrayCollection(array(
+        $colPush = new ArrayCollection([
             new GH453EmbeddedDocument(),
             new GH453EmbeddedDocument(),
             new GH453EmbeddedDocument(),
-        ));
-        $colSet = $colPush->map(function($v) { return clone $v; });
-        $colSetArray = $colPush->map(function($v) { return clone $v; });
-        $colAddToSet = $colPush->map(function($v) { return clone $v; });
+        ]);
+        $colSet = $colPush->map(function ($v) {
+            return clone $v;
+        });
+        $colSetArray = $colPush->map(function ($v) {
+            return clone $v;
+        });
+        $colAddToSet = $colPush->map(function ($v) {
+            return clone $v;
+        });
 
         $doc = new GH453Document();
         $doc->embedManyPush = $colPush;
@@ -151,21 +163,39 @@ public function testEmbedMany()
 
     public function testReferenceMany()
     {
-        $colPush = new ArrayCollection(array(
+        $colPush = new ArrayCollection([
             new GH453ReferencedDocument(),
             new GH453ReferencedDocument(),
             new GH453ReferencedDocument(),
-        ));
-        $colSet = $colPush->map(function($v) { return clone $v; });
-        $colSetArray = $colPush->map(function($v) { return clone $v; });
-        $colAddToSet = $colPush->map(function($v) { return clone $v; });
+        ]);
+        $colSet = $colPush->map(function ($v) {
+            return clone $v;
+        });
+        $colSetArray = $colPush->map(function ($v) {
+            return clone $v;
+        });
+        $colAddToSet = $colPush->map(function ($v) {
+            return clone $v;
+        });
 
         $dm = $this->dm;
 
-        $colPush->forAll(function($k, $v) use ($dm) { $dm->persist($v); return true; });
-        $colSet->forAll(function($k, $v) use ($dm) { $dm->persist($v); return true; });
-        $colSetArray->forAll(function($k, $v) use ($dm) { $dm->persist($v); return true; });
-        $colAddToSet->forAll(function($k, $v) use ($dm) { $dm->persist($v); return true; });
+        $colPush->forAll(function ($k, $v) use ($dm) {
+            $dm->persist($v);
+            return true;
+        });
+        $colSet->forAll(function ($k, $v) use ($dm) {
+            $dm->persist($v);
+            return true;
+        });
+        $colSetArray->forAll(function ($k, $v) use ($dm) {
+            $dm->persist($v);
+            return true;
+        });
+        $colAddToSet->forAll(function ($k, $v) use ($dm) {
+            $dm->persist($v);
+            return true;
+        });
 
         $doc = new GH453Document();
         $doc->referenceManyPush = $colPush;
@@ -216,13 +246,13 @@ private function assertBsonObject($documentId, $fieldName)
 
     private function assertBsonType($bsonType, $documentId, $fieldName)
     {
-        $criteria = array('_id' => $documentId);
+        $criteria = ['_id' => $documentId];
 
-        if (4 === $bsonType) {
+        if ($bsonType === 4) {
             // See: https://jira.mongodb.org/browse/SERVER-1475
             $criteria['$where'] = sprintf('Array.isArray(this.%s)', $fieldName);
         } else {
-            $criteria[$fieldName] = array('$type' => $bsonType);
+            $criteria[$fieldName] = ['$type' => $bsonType];
         }
 
         $this->assertNotNull($this->dm->getRepository(__NAMESPACE__ . '\GH453Document')->findOneBy($criteria));
@@ -240,22 +270,22 @@ private function assertBsonObjectAndValue($expectedValue, $documentId, $fieldNam
 
     private function assertBsonTypeAndValue($bsonType, $expectedValue, $documentId, $fieldName)
     {
-        if (4 === $bsonType) {
+        if ($bsonType === 4) {
             $expectedValue = array_values((array) $expectedValue);
-        } elseif (3 === $bsonType) {
+        } elseif ($bsonType === 3) {
             $expectedValue = (object) $expectedValue;
         }
 
-        $criteria = array(
+        $criteria = [
             '_id' => $documentId,
-            '$and' => array(array($fieldName => $expectedValue)),
-        );
+            '$and' => [[$fieldName => $expectedValue]],
+        ];
 
-        if (4 === $bsonType) {
+        if ($bsonType === 4) {
             // See: https://jira.mongodb.org/browse/SERVER-1475
-            $criteria['$and'][] = array('$where' => sprintf('Array.isArray(this.%s)', $fieldName));
+            $criteria['$and'][] = ['$where' => sprintf('Array.isArray(this.%s)', $fieldName)];
         } else {
-            $criteria['$and'][] = array($fieldName => array('$type' => $bsonType));
+            $criteria['$and'][] = [$fieldName => ['$type' => $bsonType]];
         }
 
         $this->assertNotNull($this->dm->getRepository(__NAMESPACE__ . '\GH453Document')->findOneBy($criteria));
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH467Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH467Test.php
index 282ae50e02..9cb246c263 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH467Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH467Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH467Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH467Test extends BaseTest
 {
     public function testMergeDocumentWithUnsetCollectionFields()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH499Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH499Test.php
index e8f49c13e9..f006b671a8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH499Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH499Test.php
@@ -1,17 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 
-class GH499Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH499Test extends BaseTest
 {
     public function testSetRefMany()
     {
-        $a = new GH499Document(new \MongoDB\BSON\ObjectId());
-        $b = new GH499Document(new \MongoDB\BSON\ObjectId());
-        $c = new GH499Document(new \MongoDB\BSON\ObjectId());
+        $a = new GH499Document(new ObjectId());
+        $b = new GH499Document(new ObjectId());
+        $c = new GH499Document(new ObjectId());
 
         $a->addRef($b);
         $a->addRef($c);
@@ -24,10 +28,10 @@ public function testSetRefMany()
 
         $collection = $this->dm->getDocumentCollection(__NAMESPACE__ . '\GH499Document');
 
-        $a = $collection->findOne(array('_id' => new \MongoDB\BSON\ObjectId($a->getId())));
+        $a = $collection->findOne(['_id' => new ObjectId($a->getId())]);
 
-        $this->assertEquals(new \MongoDB\BSON\ObjectId($b->getId()), $a['refMany'][$b->getId()]);
-        $this->assertEquals(new \MongoDB\BSON\ObjectId($c->getId()), $a['refMany'][$c->getId()]);
+        $this->assertEquals(new ObjectId($b->getId()), $a['refMany'][$b->getId()]);
+        $this->assertEquals(new ObjectId($c->getId()), $a['refMany'][$c->getId()]);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH520Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH520Test.php
index 117b51a3c5..092f64a66c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH520Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH520Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
@@ -44,7 +46,7 @@ public function testPrimeWithGetSingleResultWillNotPrimeEntireResultSet()
         $this->dm->clear();
 
         $primedIds = null;
-        $primer = function(DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$primedIds) {
+        $primer = function (DocumentManager $dm, ClassMetadata $class, array $ids, array $hints) use (&$primedIds) {
             $primedIds = $ids;
         };
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH529Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH529Test.php
index ca8828c522..a4fdfbe990 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH529Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH529Test.php
@@ -1,14 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
+use function get_class;
 
-class GH529Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH529Test extends BaseTest
 {
     public function testAutoIdWithConsistentValues()
     {
-        $identifier = new \MongoDB\BSON\ObjectId();
+        $identifier = new ObjectId();
         $doc = new GH529AutoIdDocument();
         $doc->id = $identifier;
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH560Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH560Test.php
index 73f29243f3..53ae20d164 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH560Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH560Test.php
@@ -1,22 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\EventSubscriber;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH560Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH560Test extends BaseTest
 {
     /**
      * @dataProvider provideDocumentIds
      */
     public function testPersistListenersAreCalled($id)
     {
-        $listener = new GH560EventSubscriber(array(
+        $listener = new GH560EventSubscriber([
             Events::prePersist,
             Events::postPersist,
-        ));
+        ]);
 
         $this->dm->getEventManager()->addEventSubscriber($listener);
 
@@ -25,10 +29,10 @@ public function testPersistListenersAreCalled($id)
         $this->dm->flush();
         $this->dm->clear();
 
-        $called = array(
-            array(Events::prePersist, __NAMESPACE__ . '\GH560Document'),
-            array(Events::postPersist, __NAMESPACE__ . '\GH560Document'),
-        );
+        $called = [
+            [Events::prePersist, __NAMESPACE__ . '\GH560Document'],
+            [Events::postPersist, __NAMESPACE__ . '\GH560Document'],
+        ];
 
         $this->assertEquals($called, $listener->called);
     }
@@ -52,10 +56,10 @@ public function testDocumentWithCustomIdStrategyIsSavedAndFoundFromDatabase($id)
      */
     public function testUpdateListenersAreCalled($id)
     {
-        $listener = new GH560EventSubscriber(array(
+        $listener = new GH560EventSubscriber([
             Events::preUpdate,
             Events::postUpdate,
-        ));
+        ]);
 
         $this->dm->getEventManager()->addEventSubscriber($listener);
 
@@ -67,20 +71,20 @@ public function testUpdateListenersAreCalled($id)
         $this->dm->flush();
         $this->dm->clear();
 
-        $called = array(
-            array(Events::preUpdate, __NAMESPACE__ . '\GH560Document'),
-            array(Events::postUpdate, __NAMESPACE__ . '\GH560Document'),
-        );
+        $called = [
+            [Events::preUpdate, __NAMESPACE__ . '\GH560Document'],
+            [Events::postUpdate, __NAMESPACE__ . '\GH560Document'],
+        ];
 
         $this->assertEquals($called, $listener->called);
     }
 
     public function provideDocumentIds()
     {
-        return array(
-            array(123456),
-            array('516ee7636803faea5600090a:path10421'),
-        );
+        return [
+            [123456],
+            ['516ee7636803faea5600090a:path10421'],
+        ];
     }
 }
 
@@ -91,7 +95,7 @@ class GH560EventSubscriber implements EventSubscriber
 
     public function __construct(array $events)
     {
-        $this->called = array();
+        $this->called = [];
         $this->events = $events;
     }
 
@@ -102,7 +106,7 @@ public function getSubscribedEvents()
 
     public function __call($eventName, $args)
     {
-        $this->called[] = array($eventName, get_class($args[0]->getDocument()));
+        $this->called[] = [$eventName, get_class($args[0]->getDocument())];
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH561Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH561Test.php
index c26af52df4..17d1243eaa 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH561Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH561Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH561Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH561Test extends BaseTest
 {
     public function testPersistMainDocument()
     {
@@ -19,16 +22,16 @@ public function testPersistMainDocument()
         $this->dm->flush();
         $this->dm->clear();
 
-        $document = $this->dm->find(__NAMESPACE__.'\GH561Document', $document->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH561Document', $document);
+        $document = $this->dm->find(__NAMESPACE__ . '\GH561Document', $document->id);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH561Document', $document);
         $this->assertCount(1, $document->embeddedDocuments);
 
         $embeddedDocument = $document->embeddedDocuments->first();
-        $this->assertInstanceOf(__NAMESPACE__.'\GH561EmbeddedDocument', $embeddedDocument);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH561EmbeddedDocument', $embeddedDocument);
         $this->assertCount(1, $embeddedDocument->embeddedDocuments);
 
         $anotherEmbeddedDocument = $embeddedDocument->embeddedDocuments->first();
-        $this->assertInstanceOf(__NAMESPACE__.'\GH561AnotherEmbeddedDocument', $anotherEmbeddedDocument);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH561AnotherEmbeddedDocument', $anotherEmbeddedDocument);
         $this->assertEquals('foo', $anotherEmbeddedDocument->name);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH566Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH566Test.php
index 0b46660fdc..a2ba55c071 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH566Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH566Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function iterator_to_array;
 
-class GH566Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH566Test extends BaseTest
 {
     public function testFoo()
     {
@@ -27,10 +31,10 @@ public function testFoo()
         $embeddedDoc2->parent = $doc2;
 
         $doc3->version = $embeddedDoc2;
-        $doc3->versions = new ArrayCollection(array(
+        $doc3->versions = new ArrayCollection([
             $embeddedDoc1,
             $embeddedDoc2,
-        ));
+        ]);
 
         $this->dm->flush();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH580Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH580Test.php
index c1aa60114e..880cc14aac 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH580Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH580Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use MongoDB\Driver\Exception\BulkWriteException;
 
-class GH580Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH580Test extends BaseTest
 {
     public function testDocumentPersisterShouldClearQueuedInsertsOnMongoException()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
index 5389158a72..f5697576a4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
@@ -1,12 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\DocumentNotFoundException;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function iterator_to_array;
 
-class GH593Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH593Test extends BaseTest
 {
     public function setUp()
     {
@@ -59,11 +63,8 @@ public function testReferenceManyOwningSidePreparesFilterCriteria()
         $this->assertFalse($user1following[1]->__isInitialized());
         $this->assertEquals($user3->getId(), $user1following[1]->getId());
 
-        try {
-            $user1following[1]->__load();
-            $this->fail('Expected DocumentNotFoundException for filtered Proxy object');
-        } catch (DocumentNotFoundException $e) {
-        }
+        $this->expectException(DocumentNotFoundException::class);
+        $user1following[1]->__load();
     }
 
     public function testReferenceManyInverseSidePreparesFilterCriteria()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH596Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH596Test.php
index 38e193c581..5685f9f7b5 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH596Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH596Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH596Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH596Test extends BaseTest
 {
     public function setUp()
     {
@@ -29,13 +32,17 @@ public function testExpressionPreparationDoesNotInjectFilterCriteria()
         $query = $qb->getQuery();
         $query = $query->getQuery();
 
-        $expected = array('$and' => array(
-            array('$or' => array(
-                array('name' => 'foo'),
-                array('name' => 'bar'),
-            )),
-            array('deleted' => false),
-        ));
+        $expected = [
+        '$and' => [
+            [
+        '$or' => [
+                ['name' => 'foo'],
+                ['name' => 'bar'],
+            ],
+            ],
+            ['deleted' => false],
+        ],
+        ];
 
         $this->assertEquals($expected, $query['query']);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
index 21c90b7267..fc28e76af4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 
-class GH597Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH597Test extends BaseTest
 {
     public function testEmbedManyGetsUnset()
     {
@@ -15,28 +19,28 @@ public function testEmbedManyGetsUnset()
         $this->dm->clear();
 
         // default behavior on inserts already leaves out embedded documents
-        $expectedDocument = array('_id' => new \MongoDB\BSON\ObjectId($post->getId()));
+        $expectedDocument = ['_id' => new ObjectId($post->getId())];
         $this->assertPostDocument($expectedDocument, $post);
 
         // fill documents with comments
         $post = $this->dm->find(__NAMESPACE__ . '\GH597Post', $post->getId());
-        $post->comments = new ArrayCollection(array(
+        $post->comments = new ArrayCollection([
             new GH597Comment('Comment 1'),
             new GH597Comment('Comment 2'),
-            new GH597Comment('Comment 3')
-        ));
+            new GH597Comment('Comment 3'),
+        ]);
         $this->dm->persist($post);
         $this->dm->flush();
         $this->dm->clear();
 
-        $expectedDocument = array(
-            '_id' => new \MongoDB\BSON\ObjectId($post->getId()),
-            'comments' => array(
-                array('comment' => 'Comment 1'),
-                array('comment' => 'Comment 2'),
-                array('comment' => 'Comment 3')
-            )
-        );
+        $expectedDocument = [
+            '_id' => new ObjectId($post->getId()),
+            'comments' => [
+                ['comment' => 'Comment 1'],
+                ['comment' => 'Comment 2'],
+                ['comment' => 'Comment 3'],
+            ],
+        ];
         $this->assertPostDocument($expectedDocument, $post);
 
         // trigger update
@@ -50,7 +54,7 @@ public function testEmbedManyGetsUnset()
         $this->assertCount(0, $post->getComments());
 
         // make sure embedded documents got unset
-        $expectedDocument = array('_id' => new \MongoDB\BSON\ObjectId($post->getId()));
+        $expectedDocument = ['_id' => new ObjectId($post->getId())];
         $this->assertPostDocument($expectedDocument, $post);
     }
 
@@ -62,7 +66,7 @@ public function testReferenceManyGetsUnset()
         $this->dm->clear();
 
         // default behavior on inserts already leaves out referenced documents
-        $expectedDocument = array('_id' => new \MongoDB\BSON\ObjectId($post->getId()));
+        $expectedDocument = ['_id' => new ObjectId($post->getId())];
         $this->assertPostDocument($expectedDocument, $post);
 
         // associate post with many GH597ReferenceMany documents
@@ -73,18 +77,18 @@ public function testReferenceManyGetsUnset()
         $referenceMany2 = new GH597ReferenceMany('two');
         $this->dm->persist($referenceMany2);
 
-        $post->referenceMany = new ArrayCollection(array($referenceMany1, $referenceMany2));
+        $post->referenceMany = new ArrayCollection([$referenceMany1, $referenceMany2]);
         $this->dm->persist($post);
         $this->dm->flush();
         $this->dm->clear();
 
-        $expectedDocument = array(
-            '_id' => new \MongoDB\BSON\ObjectId($post->getId()),
-            'referenceMany' => array(
-                new \MongoDB\BSON\ObjectId($referenceMany1->getId()),
-                new \MongoDB\BSON\ObjectId($referenceMany2->getId())
-            )
-        );
+        $expectedDocument = [
+            '_id' => new ObjectId($post->getId()),
+            'referenceMany' => [
+                new ObjectId($referenceMany1->getId()),
+                new ObjectId($referenceMany2->getId()),
+            ],
+        ];
         $this->assertPostDocument($expectedDocument, $post);
 
         // trigger update
@@ -98,7 +102,7 @@ public function testReferenceManyGetsUnset()
         $this->assertCount(0, $post->getReferenceMany());
 
         // make sure reference-many documents got unset
-        $expectedDocument = array('_id' => new \MongoDB\BSON\ObjectId($post->getId()));
+        $expectedDocument = ['_id' => new ObjectId($post->getId())];
         $this->assertPostDocument($expectedDocument, $post);
     }
 
@@ -106,12 +110,11 @@ public function testReferenceManyGetsUnset()
      * Asserts that raw document matches expected document.
      *
      * @param array $expected
-     * @param GH597Post $post
      */
     private function assertPostDocument(array $expected, GH597Post $post)
     {
         $collection = $this->dm->getDocumentCollection(__NAMESPACE__ . '\GH597Post');
-        $document = $collection->findOne(array('_id' => new \MongoDB\BSON\ObjectId($post->getId())));
+        $document = $collection->findOne(['_id' => new ObjectId($post->getId())]);
         $this->assertEquals($expected, $document);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
index 446b2ed877..531d75c828 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
@@ -1,12 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\DocumentNotFoundException;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function iterator_to_array;
 
-class GH602Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH602Test extends BaseTest
 {
     public function testReferenceManyOwningSidePreparesFilterCriteriaForDifferentClass()
     {
@@ -50,11 +54,8 @@ public function testReferenceManyOwningSidePreparesFilterCriteriaForDifferentCla
         $this->assertFalse($user1likes[1]->__isInitialized());
         $this->assertEquals($thing2->getId(), $user1likes[1]->getId());
 
-        try {
-            $user1likes[1]->__load();
-            $this->fail('Expected DocumentNotFoundException for filtered Proxy object');
-        } catch (DocumentNotFoundException $e) {
-        }
+        $this->expectException(DocumentNotFoundException::class);
+        $user1likes[1]->__load();
     }
 
     public function testReferenceManyInverseSidePreparesFilterCriteriaForDifferentClass()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH611Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH611Test.php
index 500507e1d6..651d4f0486 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH611Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH611Test.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\ObjectId;
 
 class GH611Test extends BaseTest
 {
     public function testPreparationofEmbeddedDocumentValues()
     {
-        $documentId = (string) (new \MongoDB\BSON\ObjectId());
+        $documentId = (string) (new ObjectId());
 
         $document = new GH611Document();
         $document->id = $documentId;
@@ -67,7 +70,7 @@ public function testPreparationofEmbeddedDocumentValues()
             ->updateOne()
             ->field('id')->equals($documentId)
             ->field('embedded._id')->exists(false)
-            ->field('embedded')->set(array('id' => 5, 'n' => 'c'))
+            ->field('embedded')->set(['id' => 5, 'n' => 'c'])
             ->getQuery()
             ->execute();
 
@@ -84,7 +87,7 @@ public function testPreparationofEmbeddedDocumentValues()
             ->updateOne()
             ->field('id')->equals($documentId)
             ->field('embedded._id')->exists(false)
-            ->field('embedded')->set((object) array('id' => 6, 'n' => 'd'))
+            ->field('embedded')->set((object) ['id' => 6, 'n' => 'd'])
             ->getQuery()
             ->execute();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH628Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH628Test.php
index 386f6d505e..1c9bec811e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH628Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH628Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -13,7 +15,7 @@ public function testQueryBuilderShouldOnlyPrepareFirstPartOfRawFields()
             ->getQuery()
             ->getQuery();
 
-        $expected = array('f.bar.baz' => 1);
+        $expected = ['f.bar.baz' => 1];
 
         $this->assertEquals($expected, $query['query']);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH665Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH665Test.php
index a6907ae883..ac9a5c91de 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH665Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH665Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH665Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH665Test extends BaseTest
 {
     public function testUseAddToSetStrategyOnEmbeddedDocument()
     {
@@ -18,12 +21,12 @@ public function testUseAddToSetStrategyOnEmbeddedDocument()
         $this->dm->clear();
 
         $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\GH665Document')
-            ->findOne(array('embeddedPushAll.name' => 'foo'));
+            ->findOne(['embeddedPushAll.name' => 'foo']);
         $this->assertNotNull($check);
         $this->assertSame($document->id, (string) $check['_id']);
 
         $check = $this->dm->getDocumentCollection(__NAMESPACE__ . '\GH665Document')
-            ->findOne(array('embeddedAddToSet.name' => 'bar'));
+            ->findOne(['embeddedAddToSet.name' => 'bar']);
         $this->assertNotNull($check);
         $this->assertSame($document->id, (string) $check['_id']);
 
@@ -33,11 +36,11 @@ public function testUseAddToSetStrategyOnEmbeddedDocument()
             ->getQuery()
             ->getSingleResult();
 
-        $expected = array(
+        $expected = [
             '_id' => $document->id,
-            'embeddedPushAll' => array(array('name' => 'foo')),
-            'embeddedAddToSet' => array(array('name' => 'bar'))
-        );
+            'embeddedPushAll' => [['name' => 'foo']],
+            'embeddedAddToSet' => [['name' => 'bar']],
+        ];
 
         $this->assertEquals($expected, $persisted);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH683Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH683Test.php
index 85e2aa8eec..9b451bff49 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH683Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH683Test.php
@@ -1,14 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\Common\Collections\ArrayCollection;
-
-use Documents\Functional\Ticket\GH683\ParentDocument;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Functional\Ticket\GH683\EmbeddedSubDocument1;
 use Documents\Functional\Ticket\GH683\EmbeddedSubDocument2;
+use Documents\Functional\Ticket\GH683\ParentDocument;
+use function get_class;
 
 class GH683Test extends BaseTest
 {
@@ -16,16 +17,16 @@ public function testEmbedOne()
     {
         $parent = new ParentDocument();
         $parent->name = 'Parent';
-        
+
         $sub1 = new EmbeddedSubDocument1();
         $sub1->name = 'Sub 1';
-        
+
         $parent->embedOne = $sub1;
 
         $this->dm->persist($parent);
         $this->dm->flush();
         $this->dm->clear();
-        
+
         $id = $parent->id;
 
         $parent = $this->dm->find(get_class($parent), $id);
@@ -36,13 +37,13 @@ public function testEmbedMany()
     {
         $parent = new ParentDocument();
         $parent->name = 'Parent';
-        
+
         $sub1 = new EmbeddedSubDocument1();
         $sub1->name = 'Sub 1';
-        
+
         $sub2 = new EmbeddedSubDocument2();
         $sub2->name = 'Sub 2';
-        
+
         $parent->embedMany = new ArrayCollection();
         $parent->embedMany->add($sub1);
         $parent->embedMany->add($sub2);
@@ -50,7 +51,7 @@ public function testEmbedMany()
         $this->dm->persist($parent);
         $this->dm->flush();
         $this->dm->clear();
-        
+
         $id = $parent->id;
 
         $parent = $this->dm->find(get_class($parent), $id);
@@ -59,5 +60,4 @@ public function testEmbedMany()
         $this->assertInstanceOf(get_class($sub1), $firstSub);
         $this->assertInstanceOf(get_class($sub2), $secondSub);
     }
-
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
index a799817f95..cbd28dc52c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\Driver\XmlDriver;
+use MongoDB\BSON\ObjectId;
+use function get_class;
 
 class GH774Test extends BaseTest
 {
     public function testUpsert()
     {
-        $id = (string) new \MongoDB\BSON\ObjectId();
+        $id = (string) new ObjectId();
 
         $thread = new GH774Thread();
         $thread->id = $id;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH788Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH788Test.php
index e5e24b41ea..bfd9bd6e36 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH788Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH788Test.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function get_class;
 
 class GH788Test extends BaseTest
 {
@@ -21,11 +24,11 @@ public function testDocumentWithDiscriminatorMap()
         $this->dm->clear();
 
         $doc = $this->dm->find(get_class($listed), $listed->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788DocumentListed', $doc);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788DocumentListed', $doc);
         $this->assertEquals('listed', $doc->name);
 
         $doc = $this->dm->find(get_class($unlisted), $unlisted->id);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788DocumentUnlisted', $doc);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788DocumentUnlisted', $doc);
         $this->assertEquals('unlisted', $doc->name);
 
         /* Attempting to find the unlisted class by the parent class will not
@@ -57,9 +60,9 @@ public function testEmbedManyWithExternalDiscriminatorMap()
         $collection = $doc->externEmbedMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedListed', $collection[0]);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedUnlisted', $collection[1]);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
 
@@ -83,9 +86,9 @@ public function testEmbedManyWithInlineDiscriminatorMap()
         $collection = $doc->inlineEmbedMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineEmbedListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineEmbedListed', $collection[0]);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineEmbedUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineEmbedUnlisted', $collection[1]);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
 
@@ -109,9 +112,9 @@ public function testEmbedManyWithNoTargetAndExternalDiscriminatorMap()
         $collection = $doc->noTargetEmbedMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedListed', $collection[0]);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedUnlisted', $collection[1]);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
 
@@ -129,7 +132,7 @@ public function testEmbedOneWithExternalDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedUnlisted', $doc->externEmbedOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedUnlisted', $doc->externEmbedOne);
         $this->assertEquals('unlisted', $doc->externEmbedOne->name);
     }
 
@@ -147,7 +150,7 @@ public function testEmbedOneWithInlineDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineEmbedUnlisted', $doc->inlineEmbedOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineEmbedUnlisted', $doc->inlineEmbedOne);
         $this->assertEquals('unlisted', $doc->inlineEmbedOne->name);
     }
 
@@ -165,7 +168,7 @@ public function testEmbedOneWithNoTargetAndExternalDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternEmbedUnlisted', $doc->noTargetEmbedOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternEmbedUnlisted', $doc->noTargetEmbedOne);
         $this->assertEquals('unlisted', $doc->noTargetEmbedOne->name);
     }
 
@@ -189,10 +192,10 @@ public function testRefManyWithExternalDiscriminatorMap()
         $collection = $doc->externRefMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefListed', $collection[0]);
         $this->assertEquals($listed->id, $collection[0]->id);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefUnlisted', $collection[1]);
         $this->assertEquals($unlisted->id, $collection[1]->id);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
@@ -217,10 +220,10 @@ public function testRefManyWithInlineDiscriminatorMap()
         $collection = $doc->inlineRefMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineRefListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineRefListed', $collection[0]);
         $this->assertEquals($listed->id, $collection[0]->id);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineRefUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineRefUnlisted', $collection[1]);
         $this->assertEquals($unlisted->id, $collection[1]->id);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
@@ -245,10 +248,10 @@ public function testRefManyWithNoTargetAndExternalDiscriminatorMap()
         $collection = $doc->noTargetRefMany;
 
         $this->assertCount(2, $collection);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefListed', $collection[0]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefListed', $collection[0]);
         $this->assertEquals($listed->id, $collection[0]->id);
         $this->assertEquals('listed', $collection[0]->name);
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefUnlisted', $collection[1]);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefUnlisted', $collection[1]);
         $this->assertEquals($unlisted->id, $collection[1]->id);
         $this->assertEquals('unlisted', $collection[1]->name);
     }
@@ -267,7 +270,7 @@ public function testRefOneWithExternalDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefUnlisted', $doc->externRefOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefUnlisted', $doc->externRefOne);
         $this->assertEquals($unlisted->id, $doc->externRefOne->id);
         $this->assertEquals('unlisted', $doc->externRefOne->name);
     }
@@ -286,7 +289,7 @@ public function testRefOneWithInlineDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788InlineRefUnlisted', $doc->inlineRefOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788InlineRefUnlisted', $doc->inlineRefOne);
         $this->assertEquals($unlisted->id, $doc->inlineRefOne->id);
         $this->assertEquals('unlisted', $doc->inlineRefOne->name);
     }
@@ -305,7 +308,7 @@ public function testRefOneWithNoTargetAndExternalDiscriminatorMap()
 
         $doc = $this->dm->find(get_class($doc), $doc->id);
 
-        $this->assertInstanceOf(__NAMESPACE__.'\GH788ExternRefUnlisted', $doc->noTargetRefOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\GH788ExternRefUnlisted', $doc->noTargetRefOne);
         $this->assertEquals($unlisted->id, $doc->noTargetRefOne->id);
         $this->assertEquals('unlisted', $doc->noTargetRefOne->name);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH816Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH816Test.php
index 0adea98af6..19d0fa85c1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH816Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH816Test.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\ObjectId;
 
-class GH816Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH816Test extends BaseTest
 {
     public function testPersistAfterDetachWithIdSet()
     {
         $d=new GH816Document();
-        $d->_id=new \MongoDB\BSON\ObjectId();
+        $d->_id=new ObjectId();
         $this->assertEmpty($this->dm->getRepository('Doctrine\ODM\MongoDB\Tests\GH816Document')->findAll());
         $this->dm->persist($d);
         $this->dm->detach($d);
@@ -20,7 +23,7 @@ public function testPersistAfterDetachWithIdSet()
     public function testPersistAfterDetachWithTitleSet()
     {
         $d=new GH816Document();
-        $d->title="Test";
+        $d->title='Test';
         $this->assertEmpty($this->dm->getRepository('Doctrine\ODM\MongoDB\Tests\GH816Document')->findAll());
         $this->dm->persist($d);
         $this->dm->detach($d);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH850Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH850Test.php
index 2356618278..9eaf329ca4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH850Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH850Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH850Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH850Test extends BaseTest
 {
     /**
      * @expectedException \InvalidArgumentException
@@ -25,7 +28,7 @@ class GH850Document
 {
     /** @ODM\Id */
     public $id;
-    
+
     /** @ODM\ReferenceOne */
-    public $refs = "";
+    public $refs = '';
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH852Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH852Test.php
index ff9662c81e..4d720c60f3 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH852Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH852Test.php
@@ -1,9 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Criteria;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\Binary;
+use function get_class;
 
 class GH852Test extends BaseTest
 {
@@ -80,18 +85,24 @@ public function testA(\Closure $idGenerator)
         // these lines are relevant for $useKeys = false in DocumentRepository::matching()
         $this->dm->clear();
         $docs = $this->dm->getRepository(get_class($parent))
-                ->matching(new \Doctrine\Common\Collections\Criteria());
+                ->matching(new Criteria());
         $this->assertCount(4, $docs);
     }
 
     public function provideIdGenerators()
     {
-        $binDataType = \MongoDB\BSON\Binary::TYPE_GENERIC;
-
-        return array(
-            array(function($id) { return array('foo' => $id); }),
-            array(function($id) use ($binDataType) { return new \MongoDB\BSON\Binary($id, $binDataType); }),
-        );
+        $binDataType = Binary::TYPE_GENERIC;
+
+        return [
+            [function ($id) {
+                return ['foo' => $id];
+            },
+            ],
+            [function ($id) use ($binDataType) {
+                return new Binary($id, $binDataType);
+            },
+            ],
+        ];
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH878Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH878Test.php
index dc9fd6e25e..ca869459a3 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH878Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH878Test.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -40,7 +42,8 @@ public function testSPLObjectHashCollisionOnDoubleMerge()
     /**
      * @return GH878Document
      */
-    private function getPersistedButDetachedDocument() {
+    private function getPersistedButDetachedDocument()
+    {
         $document = new GH878Document();
         $document->embeddedField = new GH878SubDocument();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH880Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH880Test.php
index 80ecfc4982..a2887e80c0 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH880Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH880Test.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH880Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH880Test extends BaseTest
 {
     public function test880()
     {
-        $docs = array();
+        $docs = [];
         $docs[] = new GH880Document('hello', 1);
         $docs[] = new GH880Document('world', 1);
         foreach ($docs as $doc) {
@@ -47,7 +50,7 @@ class GH880Document
     /** @ODM\Field(type="int") */
     public $category;
 
-    public function __construct($status = "", $category = 0)
+    public function __construct($status = '', $category = 0)
     {
         $this->status = $status;
         $this->category = $category;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH897Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH897Test.php
index 3de15b4766..94cd1bb92d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH897Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH897Test.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH897Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH897Test extends BaseTest
 {
     public function testRecomputeSingleDocumentChangesetForManagedDocumentWithoutChangeset()
     {
@@ -18,8 +22,8 @@ public function testRecomputeSingleDocumentChangesetForManagedDocumentWithoutCha
         $this->dm->flush();
         $this->dm->clear();
 
-        $documentA = $this->dm->find(__NAMESPACE__.'\GH897A', $documentA->id);
-        $documentB = $this->dm->find(__NAMESPACE__.'\GH897B', $documentB->id);
+        $documentA = $this->dm->find(__NAMESPACE__ . '\GH897A', $documentA->id);
+        $documentB = $this->dm->find(__NAMESPACE__ . '\GH897B', $documentB->id);
         $documentB->refOne = $documentA;
 
         /* Necessary to inject DocumentManager since it is not currently
@@ -30,7 +34,7 @@ public function testRecomputeSingleDocumentChangesetForManagedDocumentWithoutCha
         $this->dm->flush();
         $this->dm->clear();
 
-        $documentA = $this->dm->find(__NAMESPACE__.'\GH897A', $documentA->id);
+        $documentA = $this->dm->find(__NAMESPACE__ . '\GH897A', $documentA->id);
 
         $this->assertSame('a-changed', $documentA->name);
     }
@@ -63,7 +67,7 @@ class GH897B
     /** @ODM\PreFlush */
     public function preFlush()
     {
-        if ( ! $this->refOne instanceof GH897A) {
+        if (! $this->refOne instanceof GH897A) {
             return;
         }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
index 202fe38114..d97e8e25c9 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Documents\Phonenumber;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Group;
+use Documents\Phonenumber;
 use Documents\User;
 
-class GH909Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH909Test extends BaseTest
 {
     public function testManyReferenceAddAndPersist()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH921Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH921Test.php
index c60f748d03..93ca7921af 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH921Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH921Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH921Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH921Test extends BaseTest
 {
     public function testPersistentCollectionCountAndIterationShouldBeConsistent()
     {
@@ -16,7 +19,7 @@ public function testPersistentCollectionCountAndIterationShouldBeConsistent()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getRepository(__NAMESPACE__.'\GH921User')->findOneBy(['name' => 'smith']);
+        $user = $this->dm->getRepository(__NAMESPACE__ . '\GH921User')->findOneBy(['name' => 'smith']);
 
         $postA = new GH921Post();
         $user->addPost($postA);
@@ -67,12 +70,30 @@ class GH921User
     /** @ODM\ReferenceMany(targetDocument="GH921Post") */
     private $posts;
 
-    public function __construct() { $this->posts = new ArrayCollection(); }
-    public function getId() { return $this->id; }
-    public function getName() { return $this->name; }
-    public function setName($name) { $this->name = $name; }
-    public function addPost(GH921Post $post) { $this->posts[] = $post; }
-    public function getPosts() { return $this->posts; }
+    public function __construct()
+    {
+        $this->posts = new ArrayCollection();
+    }
+    public function getId()
+    {
+        return $this->id;
+    }
+    public function getName()
+    {
+        return $this->name;
+    }
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+    public function addPost(GH921Post $post)
+    {
+        $this->posts[] = $post;
+    }
+    public function getPosts()
+    {
+        return $this->posts;
+    }
 }
 
 /** @ODM\Document */
@@ -84,7 +105,16 @@ class GH921Post
     /** @ODM\Field(type="string") */
     private $name;
 
-    public function getId() { return $this->id; }
-    public function getName() { return $this->name; }
-    public function setName($name) { $this->name = $name; }
+    public function getId()
+    {
+        return $this->id;
+    }
+    public function getName()
+    {
+        return $this->name;
+    }
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH927Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH927Test.php
index 73fafeba94..9fbc1b2d27 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH927Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH927Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH927Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH927Test extends BaseTest
 {
     public function testInheritedClassHasAssociationMapping()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH928Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH928Test.php
index a40bb4edb1..4618b1ba65 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH928Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH928Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH928Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH928Test extends BaseTest
 {
     public function testNullIdCriteriaShouldNotRemoveEverything()
     {
@@ -16,11 +19,11 @@ public function testNullIdCriteriaShouldNotRemoveEverything()
         $this->dm->flush();
         $this->dm->clear();
 
-        $collection = $this->dm->getDocumentCollection(__NAMESPACE__.'\GH928Document');
+        $collection = $this->dm->getDocumentCollection(__NAMESPACE__ . '\GH928Document');
 
         $this->assertEquals(2, $collection->count());
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\GH928Document')
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\GH928Document')
             ->remove()
             ->field('id')->equals(null)
             ->getQuery()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH936Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH936Test.php
index 1ae46bfcd5..d8706dab7d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH936Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH936Test.php
@@ -1,12 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Event\LifecycleEventArgs;
+use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH936Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH936Test extends BaseTest
 {
     public function testRemoveCascadesThroughProxyDocuments()
     {
@@ -38,7 +41,7 @@ public function testRemoveCascadesThroughProxyDocuments()
 /** @ODM\Document */
 class GH936Document
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -54,7 +57,7 @@ public function __construct($ref = null)
 
 class GH936Listener
 {
-    public $removed = array();
+    public $removed = [];
 
     public function postRemove(LifecycleEventArgs $args)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH942Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH942Test.php
index ec3d19b399..0ae3453468 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH942Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH942Test.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 
-class GH942Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH942Test extends BaseTest
 {
     public function testDiscriminatorValueUsesClassNameIfMapIsNotDefined()
     {
@@ -16,7 +20,7 @@ public function testDiscriminatorValueUsesClassNameIfMapIsNotDefined()
         $this->dm->clear();
 
         $doc = $this->dm->getDocumentCollection(GH942Document::CLASSNAME)
-            ->findOne(array('_id' => new \MongoDB\BSON\ObjectId($doc->id)));
+            ->findOne(['_id' => new ObjectId($doc->id)]);
 
         $this->assertSame('foo', $doc['name']);
         $this->assertSame(GH942Document::CLASSNAME, $doc['type']);
@@ -35,13 +39,13 @@ public function testDiscriminatorValueUsesClassNameIfNotInMap()
         $this->dm->clear();
 
         $parent = $this->dm->getDocumentCollection(GH942DocumentParent::CLASSNAME)
-            ->findOne(array('_id' => new \MongoDB\BSON\ObjectId($parent->id)));
+            ->findOne(['_id' => new ObjectId($parent->id)]);
 
         $this->assertSame('parent', $parent['name']);
         $this->assertSame('p', $parent['type']);
 
         $child = $this->dm->getDocumentCollection(GH942DocumentChild::CLASSNAME)
-            ->findOne(array('_id' => new \MongoDB\BSON\ObjectId($child->id)));
+            ->findOne(['_id' => new ObjectId($child->id)]);
 
         $this->assertSame('child', $child['name']);
         $this->assertSame(GH942DocumentChild::CLASSNAME, $child['type']);
@@ -55,7 +59,7 @@ public function testDiscriminatorValueUsesClassNameIfNotInMap()
  */
 class GH942Document
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -72,7 +76,7 @@ class GH942Document
  */
 class GH942DocumentParent
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
@@ -84,5 +88,5 @@ class GH942DocumentParent
 /** @ODM\Document */
 class GH942DocumentChild extends GH942DocumentParent
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH944Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH944Test.php
index 2fd3f7a6fe..d2ebb8be9c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH944Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH944Test.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class GH944Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH944Test extends BaseTest
 {
     public function testIssue()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH971Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH971Test.php
index ca2ad111ec..6f15bcea1b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH971Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH971Test.php
@@ -1,19 +1,21 @@
 <?php
 
+declare(strict_types=1);
 
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class GH971Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH971Test extends BaseTest
 {
     public function testUpdateOfInheritedDocumentUsingFindAndUpdate()
     {
-        $name = "Ferrari";
-        $features = array(
-            "Super Engine",
-            "Huge Wheels"
-        );
+        $name = 'Ferrari';
+        $features = [
+            'Super Engine',
+            'Huge Wheels',
+        ];
 
         //first query, create Car with name "Ferrari"
         $this->dm->createQueryBuilder(__NAMESPACE__ . '\Car')
@@ -46,8 +48,8 @@ public function testUpsertThrowsExceptionWithIndecisiveDiscriminator()
         $this->dm->createQueryBuilder(__NAMESPACE__ . '\Bicycle')
             ->findAndUpdate()
             ->upsert(true)
-            ->field('name')->equals("Cool")
-            ->field('features')->push("2 people")
+            ->field('name')->equals('Cool')
+            ->field('features')->push('2 people')
             ->getQuery()->execute();
     }
 
@@ -57,8 +59,8 @@ public function testUpsertWillUseProvidedDiscriminator()
             ->findAndUpdate()
             ->upsert(true)
             ->field('type')->equals('tandem')
-            ->field('name')->equals("Cool")
-            ->field('features')->push("2 people")
+            ->field('name')->equals('Cool')
+            ->field('features')->push('2 people')
             ->getQuery()->execute();
 
         $results = $this->dm->getRepository(__NAMESPACE__ . '\Tandem')->findAll();
@@ -87,14 +89,20 @@ class Vehicle
 /**
  * @ODM\Document
  */
-class Car extends Vehicle {}
+class Car extends Vehicle
+{
+}
 
 /**
  * @ODM\Document
  */
-class Bicycle extends Vehicle {}
+class Bicycle extends Vehicle
+{
+}
 
 /**
  * @ODM\Document
  */
-class Tandem extends Bicycle {}
+class Tandem extends Bicycle
+{
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH977Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH977Test.php
index a3605703dd..8b00277a27 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH977Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH977Test.php
@@ -1,51 +1,54 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
 class GH977Test extends BaseTest
 {
     public function testAutoRecompute()
     {
         $d = new GH977TestDocument();
-        $d->value1 = "Value 1";
+        $d->value1 = 'Value 1';
         $this->dm->persist($d);
         $this->dm->flush();
         $this->dm->clear();
 
-        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => "Value 1"]);
-        $d->value1 = "Changed";
+        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => 'Value 1']);
+        $d->value1 = 'Changed';
         $this->uow->computeChangeSet($this->dm->getClassMetadata(get_class($d)), $d);
         $changeSet = $this->uow->getDocumentChangeSet($d);
         if (isset($changeSet['value1'])) {
-            $d->value2 = "v1 has changed";
+            $d->value2 = 'v1 has changed';
         }
         $this->dm->flush();
         $this->dm->clear();
-        
-        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => "Changed"]);
+
+        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => 'Changed']);
         $this->assertNotNull($d);
-        $this->assertEquals("v1 has changed", $d->value2);
+        $this->assertEquals('v1 has changed', $d->value2);
     }
 
     public function testRefreshClearsChangeSet()
     {
         $d = new GH977TestDocument();
-        $d->value1 = "Value 1";
+        $d->value1 = 'Value 1';
         $this->dm->persist($d);
         $this->dm->flush();
         $this->dm->clear();
 
-        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => "Value 1"]);
-        $d->value1 = "Changed";
+        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => 'Value 1']);
+        $d->value1 = 'Changed';
         $this->uow->computeChangeSet($this->dm->getClassMetadata(get_class($d)), $d);
         $this->dm->refresh($d);
         $this->dm->flush();
         $this->dm->clear();
 
-        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => "Value 1"]);
+        $d = $this->dm->getRepository(get_class($d))->findOneBy(['value1' => 'Value 1']);
         $this->assertNotNull($d);
     }
 }
@@ -62,4 +65,3 @@ class GH977TestDocument
     /** @ODM\Field(type="string") */
     public $value2;
 }
-
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH978Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH978Test.php
index 536008f6b6..6e9a2f8aaa 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH978Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH978Test.php
@@ -1,6 +1,10 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Ecommerce\ConfigurableProduct;
 use Documents\Ecommerce\Currency;
 use Documents\Ecommerce\Money;
@@ -10,7 +14,7 @@
 /**
  * Test for UnitOfWork::detach()
  */
-class GH978Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class GH978Test extends BaseTest
 {
     public function testDetach()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
index 3fc91eaa28..3a09882de2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
@@ -1,17 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 use Doctrine\ODM\MongoDB\Events;
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
 class GH999Test extends BaseTest
 {
     public function testModifyingInFlushHandler()
     {
-        $this->dm->getEventManager()->addEventListener(array(Events::onFlush), new GH999Listener());
+        $this->dm->getEventManager()->addEventListener([Events::onFlush], new GH999Listener());
 
         $document = new GH999Document('name');
         $this->dm->persist($document);
@@ -26,7 +29,8 @@ public function testModifyingInFlushHandler()
 
 class GH999Listener
 {
-    public function onFlush(OnFlushEventArgs $args) {
+    public function onFlush(OnFlushEventArgs $args)
+    {
         $dm = $args->getDocumentManager();
 
         foreach ($dm->getUnitOfWork()->getScheduledDocumentInsertions() as $document) {
@@ -72,4 +76,3 @@ public function postUpdate()
         throw new \Exception('Did not expect postUpdate to be called when persisting a new document');
     }
 }
-
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM116Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM116Test.php
index f0938972fb..45609a0df8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM116Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM116Test.php
@@ -1,10 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function array_values;
+use function get_class;
 
-class MODM116Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM116Test extends BaseTest
 {
     public function testIssue()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM117Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM117Test.php
index 9274945eff..3592598a8e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM117Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM117Test.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class MODM117Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM117Test extends BaseTest
 {
     public function testIssue()
     {
@@ -34,11 +38,11 @@ class MODM117User
 
     public function __get($name)
     {
-        return $this->{'_'.$name};
+        return $this->{'_' . $name};
     }
 
     public function __set($name, $value)
     {
-        $this->{'_'.$name} = $value;
+        $this->{'_' . $name} = $value;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM140Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM140Test.php
index 549a90713e..79ddb27fe8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM140Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM140Test.php
@@ -1,23 +1,24 @@
 <?php
 
-namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
+declare(strict_types=1);
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Functional\EmbeddedTestLevel0;
 use Documents\Functional\EmbeddedTestLevel1;
 use Documents\Functional\EmbeddedTestLevel2;
 
-class MODM140Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM140Test extends BaseTest
 {
-
     public function testInsertingNestedEmbeddedCollections()
     {
-        $category = new Category;
-        $category->name = "My Category";
+        $category = new Category();
+        $category->name = 'My Category';
 
-        $post1 = new Post;
+        $post1 = new Post();
         $post1->versions->add(new PostVersion('P1V1'));
         $post1->versions->add(new PostVersion('P1V2'));
 
@@ -28,7 +29,7 @@ public function testInsertingNestedEmbeddedCollections()
         $this->dm->clear();
 
         $category = $this->dm->getRepository(__NAMESPACE__ . '\Category')->findOneBy(['name' => 'My Category']);
-        $post2 = new Post;
+        $post2 = new Post();
         $post2->versions->add(new PostVersion('P2V1'));
         $post2->versions->add(new PostVersion('P2V2'));
         $category->posts->add($post2);
@@ -51,7 +52,7 @@ public function testInsertingEmbeddedCollectionWithRefMany()
         $post->comments[] = $comment;
 
         $category = new Category();
-        $category->name = "My Category";
+        $category->name = 'My Category';
         $category->posts->add($post);
 
         $this->dm->persist($comment);
@@ -74,18 +75,18 @@ public function testAddingAnotherEmbeddedDocument()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(array('name' => 'test'));
+        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(['name' => 'test']);
         $this->assertInstanceOf('Documents\Functional\EmbeddedTestLevel0', $test);
 
         $level1 = new EmbeddedTestLevel1();
-        $level1->name = "test level 1 #1";
+        $level1->name = 'test level 1 #1';
 
         $level2 = new EmbeddedTestLevel2();
-        $level2->name = "test level 2 #1 in level 1 #1";
+        $level2->name = 'test level 2 #1 in level 1 #1';
         $level1->level2[] = $level2;
 
         $level2 = new EmbeddedTestLevel2();
-        $level2->name = "test level 2 #2 in level 1 #1";
+        $level2->name = 'test level 2 #2 in level 1 #1';
         $level1->level2[] = $level2;
 
         $test->level1[] = $level1;
@@ -93,19 +94,19 @@ public function testAddingAnotherEmbeddedDocument()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(array('name' => 'test'));
+        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(['name' => 'test']);
         $this->assertCount(1, $test->level1);
         $this->assertCount(2, $test->level1[0]->level2);
 
         $level1 = new EmbeddedTestLevel1();
-        $level1->name = "test level 1 #2";
+        $level1->name = 'test level 1 #2';
 
         $level2 = new EmbeddedTestLevel2();
-        $level2->name = "test level 2 #1 in level 1 #2";
+        $level2->name = 'test level 2 #1 in level 1 #2';
         $level1->level2[] = $level2;
 
         $level2 = new EmbeddedTestLevel2();
-        $level2->name = "test level 2 #2 in level 1 #2";
+        $level2->name = 'test level 2 #2 in level 1 #2';
         $level1->level2[] = $level2;
 
         $test->level1[] = $level1;
@@ -113,69 +114,65 @@ public function testAddingAnotherEmbeddedDocument()
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(array('name' => 'test'));
+        $test = $this->dm->getRepository('Documents\Functional\EmbeddedTestLevel0')->findOneBy(['name' => 'test']);
         $this->assertCount(2, $test->level1);
         $this->assertCount(2, $test->level1[0]->level2);
         $this->assertCount(2, $test->level1[1]->level2);
     }
-
 }
 
 /** @ODM\Document */
 class Category
 {
-	/** @ODM\Id */
-	protected $id;
-
-	/** @ODM\Field(type="string") */
-	public $name;
+    /** @ODM\Id */
+    protected $id;
 
-	/** @ODM\EmbedMany(targetDocument="Post") */
-	public $posts;
+    /** @ODM\Field(type="string") */
+    public $name;
 
-	public function __construct()
-	{
-		$this->posts = new ArrayCollection();
-	}
+    /** @ODM\EmbedMany(targetDocument="Post") */
+    public $posts;
 
+    public function __construct()
+    {
+        $this->posts = new ArrayCollection();
+    }
 }
 
 /** @ODM\EmbeddedDocument */
 class Post
 {
-	/** @ODM\EmbedMany(targetDocument="PostVersion") */
-	public $versions;
+    /** @ODM\EmbedMany(targetDocument="PostVersion") */
+    public $versions;
 
-	/** @ODM\ReferenceMany(targetDocument="Comment") */
-	public $comments;
-
-	public function __construct()
-	{
-		$this->versions = new ArrayCollection();
-		$this->comments = new ArrayCollection();
-	}
+    /** @ODM\ReferenceMany(targetDocument="Comment") */
+    public $comments;
 
+    public function __construct()
+    {
+        $this->versions = new ArrayCollection();
+        $this->comments = new ArrayCollection();
+    }
 }
 
 /** @ODM\EmbeddedDocument */
 class PostVersion
 {
-	/** @ODM\Field(type="string") */
-	public $name;
-
-	public function __construct($name)
-	{
-		$this->name = $name;
-	}
+    /** @ODM\Field(type="string") */
+    public $name;
 
+    public function __construct($name)
+    {
+        $this->name = $name;
+    }
 }
 
 /** @ODM\Document */
 class Comment
 {
-	/** @ODM\Id */
-	protected $id;
+    /** @ODM\Id */
+    protected $id;
 
-	/** @ODM\Field(type="string") */
-	public $content;
+    /** @ODM\Field(type="string") */
+    public $content;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM160Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM160Test.php
index 7d85f6183c..87ff239549 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM160Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM160Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Documents\Functional\Ticket\MODM160 as MODM160;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Functional\Ticket\MODM160;
 
-class MODM160Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM160Test extends BaseTest
 {
     /**
      * @doesNotPerformAssertions
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM166Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM166Test.php
index c06d3cbf6d..a68a13e668 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM166Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM166Test.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 use Doctrine\ODM\MongoDB\Events;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Phonenumber;
 use Documents\User;
+use function get_class;
+use function sort;
 
-class MODM166Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM166Test extends BaseTest
 {
-
     public function setUp()
     {
         parent::setUp();
@@ -35,15 +39,15 @@ public function testUpdateCollectionDuringOnFlushAndRecomputSingleDocumentChange
         $this->dm->clear();
 
         $repository = $this->dm->getRepository(get_class($test));
-        $test = $repository->findOneBy(array('username' => 'lucy'));
+        $test = $repository->findOneBy(['username' => 'lucy']);
 
-        $phonenumbers = array();
-        foreach ($test->getPhonenumbers() as $phonenumber){
+        $phonenumbers = [];
+        foreach ($test->getPhonenumbers() as $phonenumber) {
             $phonenumbers[] = $phonenumber->getPhonenumber();
         }
         sort($phonenumbers);
 
-        $this->assertEquals(array('1111', '2222'), $phonenumbers);
+        $this->assertEquals(['1111', '2222'], $phonenumbers);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM167Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM167Test.php
index ff6ed6fb5c..b52906b18b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM167Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM167Test.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 use Doctrine\ODM\MongoDB\Events;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
+use function get_class;
 
-class MODM167Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM167Test extends BaseTest
 {
-
     public function setUp()
     {
         parent::setUp();
@@ -47,4 +50,4 @@ public function onFlush(OnFlushEventArgs $eventArgs)
             $unitOfWork->detach($document);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM29Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM29Test.php
index 3c5ad796d9..8313c45f05 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM29Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM29Test.php
@@ -1,18 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM29Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM29Test extends BaseTest
 {
     public function testTest()
     {
-        $collection = new \Doctrine\Common\Collections\ArrayCollection(array(
+        $collection = new ArrayCollection([
             new MODM29Embedded('0'),
             new MODM29Embedded('1'),
-            new MODM29Embedded('2')
-        ));
+            new MODM29Embedded('2'),
+        ]);
 
         // TEST CASE:
         $doc = new MODM29Doc($collection);
@@ -21,11 +25,11 @@ public function testTest()
         $this->dm->flush();
 
         // place element '0' after '1'
-        $collection = new \Doctrine\Common\Collections\ArrayCollection(array(
+        $collection = new ArrayCollection([
             $collection[1],
             $collection[0],
-            $collection[2]
-        ));
+            $collection[2],
+        ]);
 
         $doc->set($collection);
 
@@ -37,11 +41,11 @@ public function testTest()
 
         $this->dm->refresh($doc);
 
-        $array = array();
-        foreach($doc->get() as $value) {
+        $array = [];
+        foreach ($doc->get() as $value) {
             $array[] = $value->get();
         }
-        $this->assertEquals(array('1', 'tmp', '2'), $array);
+        $this->assertEquals(['1', 'tmp', '2'], $array);
     }
 }
 
@@ -54,10 +58,19 @@ class MODM29Doc
     /** @ODM\EmbedMany(targetDocument="MODM29Embedded", strategy="set") */
     protected $collection;
 
-    function __construct($c) {$this->set($c);}
+    function __construct($c)
+    {
+        $this->set($c);
+    }
 
-    function set($c) {$this->collection = $c;}
-    function get() {return $this->collection;}
+    function set($c)
+    {
+        $this->collection = $c;
+    }
+    function get()
+    {
+        return $this->collection;
+    }
 }
 
 /** @ODM\EmbeddedDocument */
@@ -66,7 +79,16 @@ class MODM29Embedded
     /** @ODM\Field(type="string") */
     protected $val;
 
-    function __construct($val) {$this->set($val);}
-    function get() {return $this->val;}
-    function set($val) {$this->val = $val;}
+    function __construct($val)
+    {
+        $this->set($val);
+    }
+    function get()
+    {
+        return $this->val;
+    }
+    function set($val)
+    {
+        $this->val = $val;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM43Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM43Test.php
index b4618376bb..357c524700 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM43Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM43Test.php
@@ -1,21 +1,25 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Event\PreLoadEventArgs;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use MongoDB\BSON\ObjectId;
+use function explode;
 
-class MODM43Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM43Test extends BaseTest
 {
     public function testTest()
     {
-        $person = array(
+        $person = [
             '_id' => new ObjectId(),
-            'name' => 'Jonathan Wage'
-        );
-        $this->dm->getDocumentCollection(__NAMESPACE__.'\Person')->insertOne($person);
-        $user = $this->dm->find(__NAMESPACE__.'\Person', $person['_id']);
+            'name' => 'Jonathan Wage',
+        ];
+        $this->dm->getDocumentCollection(__NAMESPACE__ . '\Person')->insertOne($person);
+        $user = $this->dm->find(__NAMESPACE__ . '\Person', $person['_id']);
         $this->assertEquals('Jonathan', $user->firstName);
         $this->assertEquals('Wage', $user->lastName);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
index 35922b4476..4ba40696e2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM45Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM45Test extends BaseTest
 {
     public function testTest()
     {
@@ -15,8 +18,8 @@ public function testTest()
         $this->dm->flush();
         $this->dm->clear();
 
-        $a = $this->dm->find(__NAMESPACE__.'\MODM45A', $a->getId());
-        $c = (null !== $a->getB()); 
+        $a = $this->dm->find(__NAMESPACE__ . '\MODM45A', $a->getId());
+        $c = ($a->getB() !== null);
         $this->assertTrue($c); // returns false, while expecting true
     }
 }
@@ -30,9 +33,18 @@ class MODM45A
     /** @ODM\EmbedOne(targetDocument="MODM45B") */
     protected $b;
 
-    function getId()  {return $this->id;}
-    function getB()   {return $this->b;}
-    function setB($b) {$this->b = $b;}
+    function getId()
+    {
+        return $this->id;
+    }
+    function getB()
+    {
+        return $this->b;
+    }
+    function setB($b)
+    {
+        $this->b = $b;
+    }
 }
 
 /** @ODM\EmbeddedDocument */
@@ -40,6 +52,12 @@ class MODM45B
 {
     /** @ODM\Field(type="string") */
     protected $val;
-    function setVal($val) {$this->val = $val;}
-    function getVal() {return $this->val;}
+    function setVal($val)
+    {
+        $this->val = $val;
+    }
+    function getVal()
+    {
+        return $this->val;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM46Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM46Test.php
index eb79755d58..0a18deb2c7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM46Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM46Test.php
@@ -1,21 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use MongoDB\BSON\ObjectId;
 
-class MODM46Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM46Test extends BaseTest
 {
     public function testTest()
     {
-        $a = array(
+        $a = [
             '_id' => new ObjectId(),
-            'c' => array('value' => 'value')
-        );
-        $this->dm->getDocumentCollection(__NAMESPACE__.'\MODM46A')->insertOne($a);
+            'c' => ['value' => 'value'],
+        ];
+        $this->dm->getDocumentCollection(__NAMESPACE__ . '\MODM46A')->insertOne($a);
 
-        $a = $this->dm->find(__NAMESPACE__.'\MODM46A', $a['_id']);
+        $a = $this->dm->find(__NAMESPACE__ . '\MODM46A', $a['_id']);
 
         $this->assertTrue(isset($a->b));
         $this->assertEquals('value', $a->b->value);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
index a558968e9d..e891b8b74c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
@@ -1,21 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use MongoDB\BSON\ObjectId;
 
-class MODM47Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM47Test extends BaseTest
 {
     public function testTest()
     {
-        $a = array(
+        $a = [
             '_id' => new ObjectId(),
-            'c' => 'c value'
-        );
-        $this->dm->getDocumentCollection(__NAMESPACE__.'\MODM47A')->insertOne($a);
+            'c' => 'c value',
+        ];
+        $this->dm->getDocumentCollection(__NAMESPACE__ . '\MODM47A')->insertOne($a);
 
-        $a = $this->dm->find(__NAMESPACE__.'\MODM47A', $a['_id']);
+        $a = $this->dm->find(__NAMESPACE__ . '\MODM47A', $a['_id']);
         $this->assertEquals('c value', $a->b);
     }
 }
@@ -30,6 +33,12 @@ class MODM47A
     public $b = 'tmp';
 
     /** @ODM\AlsoLoad("c") */
-    function renameC($c) {$this->b = $c;}
-    function getId() {return $this->id;}
+    function renameC($c)
+    {
+        $this->b = $c;
+    }
+    function getId()
+    {
+        return $this->id;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
index e222896a6d..438fe03b63 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM48Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM48Test extends BaseTest
 {
     public function testTest()
     {
@@ -14,7 +17,7 @@ public function testTest()
         $this->dm->flush();
         $this->dm->clear();
 
-        $a = $this->dm->find(__NAMESPACE__.'\MODM48A', $a->id);
+        $a = $this->dm->find(__NAMESPACE__ . '\MODM48A', $a->id);
         $this->assertNotNull($a);
 
         $a->getB()->setVal('test');
@@ -22,7 +25,7 @@ public function testTest()
         $this->dm->flush();
         $this->dm->clear();
 
-        $a = $this->dm->find(__NAMESPACE__.'\MODM48A', $a->id);
+        $a = $this->dm->find(__NAMESPACE__ . '\MODM48A', $a->id);
         $this->assertEquals('test', $a->getB()->getVal());
     }
 }
@@ -36,9 +39,18 @@ class MODM48A
     /** @ODM\EmbedOne(targetDocument="MODM48B") */
     public $b;
 
-    function getId()  {return $this->id;}
-    function getB()   {return $this->b;}
-    function setB($b) {$this->b = $b;}
+    function getId()
+    {
+        return $this->id;
+    }
+    function getB()
+    {
+        return $this->b;
+    }
+    function setB($b)
+    {
+        $this->b = $b;
+    }
 }
 
 /** @ODM\EmbeddedDocument */
@@ -47,6 +59,12 @@ class MODM48B
     /** @ODM\Field(type="string") */
     public $val;
 
-    function setVal($val) {$this->val = $val;}
-    function getVal() {return $this->val;}
+    function setVal($val)
+    {
+        $this->val = $val;
+    }
+    function getVal()
+    {
+        return $this->val;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM52Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM52Test.php
index 2e8d3194bf..865b2cb0ab 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM52Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM52Test.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function count;
 
-class MODM52Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM52Test extends BaseTest
 {
     public function testTest()
     {
-        $emb = new MODM52Embedded(array(new MODM52Embedded(null, 'c1'), new MODM52Embedded(null, 'c2')), 'b');
-        $doc = new MODM52Doc(array($emb), 'a');
+        $emb = new MODM52Embedded([new MODM52Embedded(null, 'c1'), new MODM52Embedded(null, 'c2')], 'b');
+        $doc = new MODM52Doc([$emb], 'a');
 
         $this->dm->persist($doc);
         $this->dm->flush();
@@ -39,7 +43,7 @@ class MODM52Container
     public $value;
 
     /** @ODM\EmbedMany(targetDocument="MODM52Embedded", strategy="set") */
-    public $items = array();
+    public $items = [];
 
     public function __construct($items = null, $value = null)
     {
@@ -67,7 +71,8 @@ public function removeItem($i)
 
 /** @ODM\EmbeddedDocument */
 class MODM52Embedded extends MODM52Container
-{}
+{
+}
 
 /** @ODM\Document */
 class MODM52Doc extends MODM52Container
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM56Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM56Test.php
index 9bfc8a8860..70fea20874 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM56Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM56Test.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\UTCDateTime;
 
-class MODM56Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM56Test extends BaseTest
 {
     public function testTest()
     {
@@ -19,10 +23,10 @@ public function testTest()
         $parent->children[] = $childTwo;
         $this->dm->flush();
 
-        $test = $this->dm->getDocumentCollection(__NAMESPACE__.'\MODM56Parent')->findOne();
+        $test = $this->dm->getDocumentCollection(__NAMESPACE__ . '\MODM56Parent')->findOne();
 
         $this->assertEquals('Parent', $test['name']);
-        $this->assertInstanceOf(\MongoDB\BSON\UTCDateTime::class, $test['updatedAt']);
+        $this->assertInstanceOf(UTCDateTime::class, $test['updatedAt']);
         $this->assertCount(2, $test['children']);
         $this->assertEquals('Child One', $test['children'][0]['name']);
         $this->assertEquals('Child Two', $test['children'][1]['name']);
@@ -42,7 +46,7 @@ class MODM56Parent
     public $updatedAt;
 
     /** @ODM\EmbedMany(targetDocument="MODM56Child") */
-    public $children = array();
+    public $children = [];
 
     public function __construct($name)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM62Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM62Test.php
index 83fd66403b..62dfebe510 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM62Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM62Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM62Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM62Test extends BaseTest
 {
     public function testTest()
     {
@@ -13,12 +16,12 @@ public function testTest()
         $this->dm->flush();
         $this->dm->refresh($test);
 
-        $test->setB(array('test', 'test2'));
+        $test->setB(['test', 'test2']);
         $this->dm->flush();
         $this->dm->clear();
 
-        $test = $this->dm->find(__NAMESPACE__.'\MODM62Document', $test->id);
-        $this->assertEquals(array('test', 'test2'), $test->b);
+        $test = $this->dm->find(__NAMESPACE__ . '\MODM62Document', $test->id);
+        $this->assertEquals(['test', 'test2'], $test->b);
     }
 }
 
@@ -29,7 +32,10 @@ class MODM62Document
     public $id;
 
     /** @ODM\Field(type="collection") */
-    public $b = array('ok');
+    public $b = ['ok'];
 
-    public function setB($b) {$this->b = $b;}
+    public function setB($b)
+    {
+        $this->b = $b;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM65Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM65Test.php
index c6f47c74b4..b24152fa82 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM65Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM65Test.php
@@ -1,10 +1,13 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM65Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM65Test extends BaseTest
 {
     public function testTest()
     {
@@ -16,11 +19,11 @@ public function testTest()
         $this->dm->flush();
         $this->dm->clear();
 
-        $user = $this->dm->getDocumentCollection(__NAMESPACE__.'\MODM65User')->findOne();
+        $user = $this->dm->getDocumentCollection(__NAMESPACE__ . '\MODM65User')->findOne();
         $this->assertTrue(isset($user['snu']['lN']));
         $this->assertTrue(isset($user['snu']['fN']));
 
-        $user = $this->dm->find(__NAMESPACE__.'\MODM65User', $user['_id']);
+        $user = $this->dm->find(__NAMESPACE__ . '\MODM65User', $user['_id']);
         $this->assertEquals('Jonathan', $user->socialNetworkUser->firstName);
         $this->assertEquals('Wage', $user->socialNetworkUser->lastName);
     }
@@ -31,20 +34,20 @@ public function testTest()
  */
 class MODM65User
 {
-	/**
-	 * @ODM\Id
-	 */
-	public $id;
-	/**
-	 * @ODM\EmbedOne(
-	 * 	discriminatorField="php",
-	 * 	discriminatorMap={
-	 * 		"fbu"="Doctrine\ODM\MongoDB\Tests\Functional\Ticket\MODM65SocialNetworkUser"
-	 * 	},
-	 * 	name="snu"
-	 * )
-	 */
-	public $socialNetworkUser;
+    /**
+     * @ODM\Id
+     */
+    public $id;
+    /**
+     * @ODM\EmbedOne(
+     *  discriminatorField="php",
+     *  discriminatorMap={
+     *      "fbu"="Doctrine\ODM\MongoDB\Tests\Functional\Ticket\MODM65SocialNetworkUser"
+     *  },
+     *  name="snu"
+     * )
+     */
+    public $socialNetworkUser;
 }
 
 /**
@@ -52,14 +55,14 @@ class MODM65User
  */
 class MODM65SocialNetworkUser
 {
-	/**
-	 * @ODM\Field(name="fN", type="string")
-	 * @var string
-	 */
-	public $firstName;
-	/**
-	 * @ODM\Field(name="lN", type="string")
-	 * @var string
-	 */
-	public $lastName;
+    /**
+     * @ODM\Field(name="fN", type="string")
+     * @var string
+     */
+    public $firstName;
+    /**
+     * @ODM\Field(name="lN", type="string")
+     * @var string
+     */
+    public $lastName;
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM66Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM66Test.php
index 60721e246a..06db0f0292 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM66Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM66Test.php
@@ -1,17 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM66Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM66Test extends BaseTest
 {
-
     public function testTest()
     {
         $b1 = new MODM52B('first');
-        $a = new MODM52A(array($b1));
+        $a = new MODM52A([$b1]);
         $this->dm->persist($a);
         $this->dm->flush();
         $b2 = new MODM52B('second');
@@ -23,17 +25,19 @@ public function testTest()
 
         $this->assertCount(2, $b);
 
-        $this->assertEquals(array(
-            $b1->getId(), $b2->getId()
-            ), array(
-            $b[0]->getId(), $b[1]->getId()
-        ));
+        $this->assertEquals([
+            $b1->getId(),
+        $b2->getId(),
+            ], [
+            $b[0]->getId(),
+        $b[1]->getId(),
+            ]);
     }
 
     public function testRefresh()
     {
         $b1 = new MODM52B('first');
-        $a = new MODM52A(array($b1));
+        $a = new MODM52A([$b1]);
         $this->dm->persist($a);
         $this->dm->flush();
         $b2 = new MODM52B('second');
@@ -47,13 +51,14 @@ public function testRefresh()
 
         $this->assertCount(2, $b);
 
-        $this->assertEquals(array(
-            $b1->getId(), $b2->getId()
-            ), array(
-            $b[0]->getId(), $b[1]->getId()
-        ));
+        $this->assertEquals([
+            $b1->getId(),
+        $b2->getId(),
+            ], [
+            $b[0]->getId(),
+        $b[1]->getId(),
+            ]);
     }
-
 }
 
 /** @ODM\Document */
@@ -79,7 +84,6 @@ function getB()
 /** @ODM\Document */
 class MODM52B
 {
-
     /** @ODM\Id */
     protected $id;
 
@@ -95,5 +99,4 @@ public function getId()
     {
         return $this->id;
     }
-
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM67Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM67Test.php
index 12d846b8fc..76ceebf2fa 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM67Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM67Test.php
@@ -1,24 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Event\LifecycleEventArgs;
+use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM67Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM67Test extends BaseTest
 {
     private function getDocumentManager()
     {
         $this->listener = new MODM67TestEventListener($this->dm);
         $evm = $this->dm->getEventManager();
-        $events = array(
+        $events = [
             Events::prePersist,
             Events::postPersist,
             Events::preUpdate,
             Events::postUpdate,
-        );
+        ];
         $evm->addEventListener($events, $this->listener);
 
         return $this->dm;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
index 48b2eed454..4bb13d128b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
@@ -1,27 +1,31 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function array_search;
 
-class MODM70Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM70Test extends BaseTest
 {
     public function testTest()
     {
-		$avatar = new Avatar('Test', 1, array(new AvatarPart('#000')));
+        $avatar = new Avatar('Test', 1, [new AvatarPart('#000')]);
 
-		$this->dm->persist($avatar);
-		$this->dm->flush();
-		$this->dm->refresh($avatar);
+        $this->dm->persist($avatar);
+        $this->dm->flush();
+        $this->dm->refresh($avatar);
 
-		$avatar->addAvatarPart(new AvatarPart('#FFF'));
+        $avatar->addAvatarPart(new AvatarPart('#FFF'));
 
-		$this->dm->flush();
-		$this->dm->refresh($avatar);
+        $this->dm->flush();
+        $this->dm->refresh($avatar);
 
-		$parts = $avatar->getAvatarParts();
-		$this->assertCount(2, $parts);
-		$this->assertEquals('#FFF', $parts[1]->getColor());
+        $parts = $avatar->getAvatarParts();
+        $this->assertCount(2, $parts);
+        $this->assertEquals('#FFF', $parts[1]->getColor());
     }
 }
 
@@ -30,87 +34,86 @@ public function testTest()
  */
 class Avatar
 {
+    /**
+     * @ODM\Id
+     */
+    protected $id;
+
+    /**
+     * @ODM\Field(name="na", type="string")
+     * @var string
+     */
+    protected $name;
+
+    /**
+     * @ODM\Field(name="sex", type="int")
+     * @var int
+     */
+    protected $sex;
+
+    /**
+     * @ODM\EmbedMany(
+     *  targetDocument="AvatarPart",
+     *  name="aP"
+     * )
+     * @var array AvatarPart
+     */
+    protected $avatarParts;
+
+    public function __construct($name, $sex, $avatarParts = null)
+    {
+        $this->name = $name;
+        $this->sex = $sex;
+        $this->avatarParts = $avatarParts;
+    }
+
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    public function getSex()
+    {
+        return $this->sex;
+    }
+
+    public function setSex($sex)
+    {
+        $this->sex = $sex;
+    }
+
+    public function getAvatarParts()
+    {
+        return $this->avatarParts;
+    }
+
+    public function addAvatarPart($part)
+    {
+        $this->avatarParts[] = $part;
+    }
 
-	/**
-	 * @ODM\Id
-	 */
-	protected $id;
-
-	/**
-	 * @ODM\Field(name="na", type="string")
-	 * @var string
-	 */
-	protected $name;
-
-	/**
-	 * @ODM\Field(name="sex", type="int")
-	 * @var int
-	 */
-	protected $sex;
-
-	/**
-	 * @ODM\EmbedMany(
-	 *	targetDocument="AvatarPart",
-	 *	name="aP"
-	 * )
-	 * @var array AvatarPart
-	 */
-	protected $avatarParts;
-
-	public function __construct($name, $sex, $avatarParts = null)
-	{
-		$this->name = $name;
-		$this->sex = $sex;
-		$this->avatarParts = $avatarParts;
-	}
-
-	public function getId()
-	{
-		return $this->id;
-	}
-
-	public function getName()
-	{
-		return $this->name;
-	}
-
-	public function setName($name)
-	{
-		$this->name = $name;
-	}
-
-	public function getSex()
-	{
-		return $this->sex;
-	}
-
-	public function setSex($sex)
-	{
-		$this->sex = $sex;
-	}
-
-	public function getAvatarParts()
-	{
-		return $this->avatarParts;
-	}
-
-	public function addAvatarPart($part)
-	{
-		$this->avatarParts[] = $part;
-	}
-
-	public function setAvatarParts($parts)
-	{
-		$this->avatarParts = $parts;
-	}
-
-	public function removeAvatarPart($part)
-	{
-		$key = array_search($this->avatarParts, $part);
-		if ($key !== false) {
-			unset($this->avatarParts[$key]);
-		}
-	}
+    public function setAvatarParts($parts)
+    {
+        $this->avatarParts = $parts;
+    }
+
+    public function removeAvatarPart($part)
+    {
+        $key = array_search($this->avatarParts, $part);
+        if ($key !== false) {
+            unset($this->avatarParts[$key]);
+        }
+    }
 }
 
 /**
@@ -118,24 +121,24 @@ public function removeAvatarPart($part)
  */
 class AvatarPart
 {
-	/**
-	 * @ODM\Field(name="col", type="string")
-	 * @var string
-	 */
-	protected $color;
-
-	public function __construct($color = null)
-	{
-		$this->color = $color;
-	}
-
-	public function getColor()
-	{
-		return $this->color;
-	}
-
-	public function setColor($color)
-	{
-		$this->color = $color;
-	}
+    /**
+     * @ODM\Field(name="col", type="string")
+     * @var string
+     */
+    protected $color;
+
+    public function __construct($color = null)
+    {
+        $this->color = $color;
+    }
+
+    public function getColor()
+    {
+        return $this->color;
+    }
+
+    public function setColor($color)
+    {
+        $this->color = $color;
+    }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM72Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM72Test.php
index 25a24288a6..301a0b2f09 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM72Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM72Test.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM72Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM72Test extends BaseTest
 {
     public function testTest()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\MODM72User');
-        $this->assertEquals(array('test' => 'test'), $class->fieldMappings['name']['options']);
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\MODM72User');
+        $this->assertEquals(['test' => 'test'], $class->fieldMappings['name']['options']);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM76Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM76Test.php
index 7334acb62b..663fc5a345 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM76Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM76Test.php
@@ -1,19 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM76Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM76Test extends BaseTest
 {
     public function testTest()
     {
-        $c1 = new MODM76C;
-        $c2 = new MODM76C;
+        $c1 = new MODM76C();
+        $c2 = new MODM76C();
 
         $b = new MODM76B($c1);
-        $a = new MODM76A(array($b), array($c1));
+        $a = new MODM76A([$b], [$c1]);
 
         $this->dm->persist($a);
         $this->dm->persist($b);
@@ -21,7 +24,7 @@ public function testTest()
         $this->dm->persist($c2);
         $this->dm->flush();
 
-        $this->assertTrue($a->getId() != null);
+        $this->assertTrue($a->getId() !== null);
     }
 }
 
@@ -35,10 +38,10 @@ class MODM76A
     protected $test = 'test';
 
     /** @ODM\EmbedMany(targetDocument="MODM76B") */
-    protected $b = array();
+    protected $b = [];
 
     /** @ODM\ReferenceMany(targetDocument="MODM76C") */
-    protected $c = array();
+    protected $c = [];
 
     public function __construct($b, $c)
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM81Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM81Test.php
index 278359aff0..d3b4aa82a9 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM81Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM81Test.php
@@ -1,11 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class MODM81Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM81Test extends BaseTest
 {
     /**
      * @return DocumentManager
@@ -30,8 +33,8 @@ public function testDocumentIdWithSameProxyId()
         $dm->flush();
 
         $embedded = new MODM81TestEmbeddedDocument($doc1, $doc2, 'Test1');
-        $doc1->setEmbeddedDocuments(array($embedded));
-        $doc2->setEmbeddedDocuments(array($embedded));
+        $doc1->setEmbeddedDocuments([$embedded]);
+        $doc2->setEmbeddedDocuments([$embedded]);
 
         $dm->flush();
         $dm->clear();
@@ -95,7 +98,7 @@ public function setName($name)
     }
 
     /**
-     * @return \Doctrine\Common\Collections\ArrayCollection
+     * @return ArrayCollection
      */
     public function getEmbeddedDocuments()
     {
@@ -109,7 +112,6 @@ public function setEmbeddedDocuments($documents)
     {
         $this->embeddedDocuments = new ArrayCollection($documents);
     }
-
 }
 
 /** @ODM\EmbeddedDocument */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM83Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM83Test.php
index 2669ee6851..727ab0c12e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM83Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM83Test.php
@@ -1,20 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class MODM83Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM83Test extends BaseTest
 {
     private function getDocumentManager()
     {
         $this->listener = new MODM83EventListener();
         $evm = $this->dm->getEventManager();
-        $events = array(
+        $events = [
             Events::preUpdate,
             Events::postUpdate,
-        );
+        ];
         $evm->addEventListener($events, $this->listener);
         return $this->dm;
     }
@@ -34,23 +38,23 @@ public function testDocumentWithEmbeddedDocumentNotUpdated()
         $dm->flush();
         $dm->clear();
 
-        $won = $dm->find(__NAMESPACE__.'\MODM83TestDocument', $won->id);
-        $too = $dm->find(__NAMESPACE__.'\MODM83OtherDocument', $too->id);
+        $won = $dm->find(__NAMESPACE__ . '\MODM83TestDocument', $won->id);
+        $too = $dm->find(__NAMESPACE__ . '\MODM83OtherDocument', $too->id);
         $too->name = 'Bob';
         $dm->flush();
         $dm->clear();
 
-        $called = array(
-            Events::preUpdate  => array(__NAMESPACE__.'\MODM83OtherDocument'),
-            Events::postUpdate => array(__NAMESPACE__.'\MODM83OtherDocument')
-        );
+        $called = [
+            Events::preUpdate  => [__NAMESPACE__ . '\MODM83OtherDocument'],
+            Events::postUpdate => [__NAMESPACE__ . '\MODM83OtherDocument'],
+        ];
         $this->assertEquals($called, $this->listener->called);
     }
 }
 
 class MODM83EventListener
 {
-    public $called = array();
+    public $called = [];
     public function __call($method, $args)
     {
         $document = $args[0]->getDocument();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM88Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM88Test.php
index b4781b3db8..2ce8ad3e16 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM88Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM88Test.php
@@ -1,12 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
-class MODM88Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\Article;
+
+class MODM88Test extends BaseTest
 {
     public function testTest()
     {
-        $article = new \Documents\Article;
+        $article = new Article();
         $article->setTitle('Test Title');
         $article->setBody('Test Body');
         $this->dm->persist($article);
@@ -17,7 +22,7 @@ public function testTest()
             ->select('_id', 'title');
         $q = $qb->getQuery();
         $document = $q->getSingleResult();
-        
+
         $this->assertEquals('Test Title', $document->getTitle());
         $this->assertNull($document->getBody());
 
@@ -28,4 +33,4 @@ public function testTest()
         $this->assertEquals('changed', $check['title']);
         $this->assertEquals('Test Body', $check['body']);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM90Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM90Test.php
index ee0dd3fc73..2ca33005d8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM90Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM90Test.php
@@ -1,20 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class MODM90Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM90Test extends BaseTest
 {
     private function getDocumentManager()
     {
         $this->listener = new MODM90EventListener();
         $evm = $this->dm->getEventManager();
-        $events = array(
+        $events = [
             Events::preUpdate,
             Events::postUpdate,
-        );
+        ];
         $evm->addEventListener($events, $this->listener);
         return $this->dm;
     }
@@ -31,14 +35,14 @@ public function testDocumentWithEmbeddedDocumentNotUpdatedOnFlush()
         $dm->flush();
         $dm->clear();
 
-        $testDoc = $dm->find(__NAMESPACE__.'\MODM90TestDocument', $testDoc->id);
+        $testDoc = $dm->find(__NAMESPACE__ . '\MODM90TestDocument', $testDoc->id);
 
         // run a flush, in theory, nothing should be flushed.
         $dm->flush();
         $dm->clear();
 
         // no update events should be called
-        $called = array();
+        $called = [];
         $this->assertEquals($called, $this->listener->called);
     }
 
@@ -58,7 +62,7 @@ public function testDiscriminatorFieldValuePresentIfRealProperty()
         $dm->flush();
         $dm->clear();
 
-        $testDoc = $dm->find(__NAMESPACE__.'\MODM90TestDocument', $testDoc->id);
+        $testDoc = $dm->find(__NAMESPACE__ . '\MODM90TestDocument', $testDoc->id);
 
         $this->assertEquals($testDoc->embedded->type, 'test2');
     }
@@ -66,7 +70,7 @@ public function testDiscriminatorFieldValuePresentIfRealProperty()
 
 class MODM90EventListener
 {
-    public $called = array();
+    public $called = [];
     public function __call($method, $args)
     {
         $document = $args[0]->getDocument();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM91Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM91Test.php
index 38025f2ad5..7860556aa7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM91Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM91Test.php
@@ -1,20 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function get_class;
 
-class MODM91Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM91Test extends BaseTest
 {
     private function getDocumentManager()
     {
         $this->listener = new MODM91EventListener();
         $evm = $this->dm->getEventManager();
-        $events = array(
+        $events = [
             Events::preUpdate,
             Events::postUpdate,
-        );
+        ];
         $evm->addEventListener($events, $this->listener);
         return $this->dm;
     }
@@ -31,18 +35,18 @@ public function testDocumentWithEmbeddedDocumentNotUpdated()
         $dm->flush();
         $dm->clear();
 
-        $testDoc = $dm->find(__NAMESPACE__.'\MODM91TestDocument', $testDoc->id);
+        $testDoc = $dm->find(__NAMESPACE__ . '\MODM91TestDocument', $testDoc->id);
         $dm->flush();
         $dm->clear();
 
-        $called = array();
+        $called = [];
         $this->assertEquals($called, $this->listener->called);
     }
 }
 
 class MODM91EventListener
 {
-    public $called = array();
+    public $called = [];
     public function __call($method, $args)
     {
         $document = $args[0]->getDocument();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM92Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM92Test.php
index 5972ef1ebd..f5b5b71733 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM92Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM92Test.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function is_array;
 
-class MODM92Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM92Test extends BaseTest
 {
     public function testDocumentWithEmbeddedDocuments()
     {
-        $embeddedDocuments = array(new MODM92TestEmbeddedDocument('foo'));
+        $embeddedDocuments = [new MODM92TestEmbeddedDocument('foo')];
 
         $testDoc = new MODM92TestDocument();
         $testDoc->setEmbeddedDocuments($embeddedDocuments);
@@ -17,17 +21,17 @@ public function testDocumentWithEmbeddedDocuments()
         $this->dm->flush();
         $this->dm->clear();
 
-        $testDoc = $this->dm->find(__NAMESPACE__.'\MODM92TestDocument', $testDoc->id);
+        $testDoc = $this->dm->find(__NAMESPACE__ . '\MODM92TestDocument', $testDoc->id);
         $this->assertEquals($embeddedDocuments, $testDoc->embeddedDocuments->toArray());
 
-        $embeddedDocuments = array(new MODM92TestEmbeddedDocument('bar'));
+        $embeddedDocuments = [new MODM92TestEmbeddedDocument('bar')];
 
         $testDoc->setEmbeddedDocuments($embeddedDocuments);
         $this->assertEquals($embeddedDocuments, $testDoc->embeddedDocuments->toArray());
 
         $this->dm->flush();
         $this->dm->clear();
-        $testDoc = $this->dm->find(__NAMESPACE__.'\MODM92TestDocument', $testDoc->id);
+        $testDoc = $this->dm->find(__NAMESPACE__ . '\MODM92TestDocument', $testDoc->id);
 
         $this->assertEquals($embeddedDocuments, $testDoc->embeddedDocuments->toArray());
     }
@@ -43,7 +47,8 @@ class MODM92TestDocument
     /** @ODM\EmbedMany(targetDocument="MODM92TestEmbeddedDocument") */
     public $embeddedDocuments;
 
-    public function __construct() {
+    public function __construct()
+    {
         $this->embeddedDocuments = new ArrayCollection();
     }
 
@@ -58,7 +63,8 @@ public function __construct() {
      *
      * @param array|Traversable $children
      */
-    public function setEmbeddedDocuments($embeddedDocuments) {
+    public function setEmbeddedDocuments($embeddedDocuments)
+    {
         $this->embeddedDocuments->clear();
 
         if (! (is_array($embeddedDocuments) || $embeddedDocuments instanceof \Traversable)) {
@@ -77,7 +83,8 @@ class MODM92TestEmbeddedDocument
     /** @ODM\Field(type="string") */
     public $name;
 
-    public function __construct($name) {
+    public function __construct($name)
+    {
         $this->name = $name;
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM95Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM95Test.php
index b38e52ee85..ec08cd1d32 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM95Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM95Test.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function is_array;
 
-class MODM95Test extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MODM95Test extends BaseTest
 {
     public function testDocumentWithEmbeddedDocuments()
     {
-        $embeddedDocuments = array(new MODM95TestEmbeddedDocument('foo'));
+        $embeddedDocuments = [new MODM95TestEmbeddedDocument('foo')];
 
         $testDoc = new MODM95TestDocument();
         $testDoc->setEmbeddedDocuments($embeddedDocuments);
@@ -17,7 +21,7 @@ public function testDocumentWithEmbeddedDocuments()
         $this->dm->flush();
         $this->dm->clear();
 
-        $testDoc = $this->dm->find(__NAMESPACE__.'\MODM95TestDocument', $testDoc->id);
+        $testDoc = $this->dm->find(__NAMESPACE__ . '\MODM95TestDocument', $testDoc->id);
 
         $this->assertEquals($embeddedDocuments, $testDoc->embeddedDocuments->toArray());
 
@@ -25,14 +29,14 @@ public function testDocumentWithEmbeddedDocuments()
         $this->dm->flush();
         $this->dm->clear();
 
-        $testDocLoad = $this->dm->find(__NAMESPACE__.'\MODM95TestDocument', $testDoc->id);
+        $testDocLoad = $this->dm->find(__NAMESPACE__ . '\MODM95TestDocument', $testDoc->id);
         $this->assertNull($testDocLoad);
 
         $this->dm->persist($testDoc);
         $this->dm->flush();
         $this->dm->clear();
 
-        $testDocLoad = $this->dm->find(__NAMESPACE__.'\MODM95TestDocument', $testDoc->id);
+        $testDocLoad = $this->dm->find(__NAMESPACE__ . '\MODM95TestDocument', $testDoc->id);
         $this->assertNotNull($testDocLoad);
 
         $this->assertEquals($embeddedDocuments, $testDocLoad->embeddedDocuments->toArray());
@@ -49,7 +53,8 @@ class MODM95TestDocument
     /** @ODM\EmbedMany(targetDocument="MODM95TestEmbeddedDocument") */
     public $embeddedDocuments;
 
-    public function __construct() {
+    public function __construct()
+    {
         $this->embeddedDocuments = new ArrayCollection();
     }
 
@@ -64,7 +69,8 @@ public function __construct() {
      *
      * @param array|Traversable $children
      */
-    public function setEmbeddedDocuments($embeddedDocuments) {
+    public function setEmbeddedDocuments($embeddedDocuments)
+    {
         $this->embeddedDocuments->clear();
 
         if (! (is_array($embeddedDocuments) || $embeddedDocuments instanceof \Traversable)) {
@@ -83,7 +89,8 @@ class MODM95TestEmbeddedDocument
     /** @ODM\Field(type="string") */
     public $name;
 
-    public function __construct($name) {
+    public function __construct($name)
+    {
         $this->name = $name;
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
index 4bf88967fe..8ba6ec4477 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\ObjectId;
 
-class UpsertTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class UpsertTest extends BaseTest
 {
     /**
      * Tests for "MongoCursorException: Cannot apply $push/$pushAll modifier to non-array" error.
@@ -14,10 +18,10 @@ class UpsertTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
     public function testUpsertEmbedManyDoesNotCreateObject()
     {
         $test = new UpsertTestUser();
-        $test->id = (string) new \MongoDB\BSON\ObjectId();
+        $test->id = (string) new ObjectId();
 
         $embedded = new UpsertTestUserEmbedded();
-        $embedded->id = (string) new \MongoDB\BSON\ObjectId();
+        $embedded->id = (string) new ObjectId();
         $embedded->test = 'test';
 
         $test->embedMany[] = $embedded;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/VersionTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/VersionTest.php
index 4eb41efe8d..243595e0e3 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/VersionTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/VersionTest.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Functional;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class VersionTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class VersionTest extends BaseTest
 {
     public function testVersioningWhenManipulatingEmbedMany()
     {
@@ -20,19 +24,19 @@ public function testVersioningWhenManipulatingEmbedMany()
         $doc->embedMany[] = new VersionedEmbeddedDocument('embed 3');
         $this->dm->flush();
         $this->assertEquals($expectedVersion++, $doc->version);
-        
+
         $doc->embedMany[0]->embedMany[] = new VersionedEmbeddedDocument('deeply embed 1');
         $this->dm->flush();
         $this->assertEquals($expectedVersion++, $doc->version);
-        
+
         unset($doc->embedMany[1]);
         $this->dm->flush();
         $this->assertEquals($expectedVersion++, $doc->version);
 
         $doc->embedMany->clear();
         $this->dm->flush();
-        $this->assertEquals($expectedVersion++, $doc->version); 
-        
+        $this->assertEquals($expectedVersion++, $doc->version);
+
         $doc->embedMany = null;
         $this->dm->flush();
         $this->assertEquals($expectedVersion++, $doc->version);
@@ -46,19 +50,19 @@ class VersionedDocument
 {
     /** @ODM\Id */
     public $id;
-    
+
     /** @ODM\Field(type="int", name="_version") @ODM\Version */
     public $version = 1;
-    
+
     /** @ODM\Field(type="string") */
     public $name;
-    
+
     /** @ODM\EmbedMany(targetDocument="VersionedEmbeddedDocument") */
-    public $embedMany = array();
-    
+    public $embedMany = [];
+
     public function __construct()
     {
-        $this->embedMany = new \Doctrine\Common\Collections\ArrayCollection();
+        $this->embedMany = new ArrayCollection();
     }
 }
 
@@ -69,13 +73,13 @@ class VersionedEmbeddedDocument
 {
     /** @ODM\Field(type="string") */
     public $value;
-    
+
     /** @ODM\EmbedMany(targetDocument="VersionedEmbeddedDocument") */
     public $embedMany;
-    
-    public function __construct($value) 
+
+    public function __construct($value)
     {
         $this->value = $value;
-        $this->embedMany = new \Doctrine\Common\Collections\ArrayCollection();
+        $this->embedMany = new ArrayCollection();
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/HydratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/HydratorTest.php
index 5fa4815908..50c36b8918 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/HydratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/HydratorTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -9,34 +11,30 @@ class HydratorTest extends BaseTest
 {
     public function testHydrator()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\HydrationClosureUser');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\HydrationClosureUser');
 
         $user = new HydrationClosureUser();
-        $this->dm->getHydratorFactory()->hydrate($user, array(
+        $this->dm->getHydratorFactory()->hydrate($user, [
             '_id' => 1,
             'title' => null,
             'name' => 'jon',
             'birthdate' => new \DateTime('1961-01-01'),
-            'referenceOne' => array('$id' => '1'),
-            'referenceMany' => array(
-                array(
-                    '$id' => '1'
-                ),
-                array(
-                    '$id' => '2'
-                )
-            ),
-            'embedOne' => array('name' => 'jon'),
-            'embedMany' => array(
-                array('name' => 'jon')
-            )
-        ));
+            'referenceOne' => ['$id' => '1'],
+            'referenceMany' => [
+                ['$id' => '1'],
+                ['$id' => '2'],
+            ],
+            'embedOne' => ['name' => 'jon'],
+            'embedMany' => [
+                ['name' => 'jon'],
+            ],
+        ]);
 
         $this->assertEquals(1, $user->id);
         $this->assertNull($user->title);
         $this->assertEquals('jon', $user->name);
         $this->assertInstanceOf('DateTime', $user->birthdate);
-        $this->assertInstanceOf(__NAMESPACE__.'\HydrationClosureReferenceOne', $user->referenceOne);
+        $this->assertInstanceOf(__NAMESPACE__ . '\HydrationClosureReferenceOne', $user->referenceOne);
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\PersistentCollection', $user->referenceMany);
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\Proxy\Proxy', $user->referenceMany[0]);
         $this->assertInstanceOf('Doctrine\ODM\MongoDB\Proxy\Proxy', $user->referenceMany[1]);
@@ -47,7 +45,7 @@ public function testHydrator()
 
     public function testReadOnly()
     {
-        $class = $this->dm->getClassMetadata(__NAMESPACE__.'\HydrationClosureUser');
+        $class = $this->dm->getClassMetadata(__NAMESPACE__ . '\HydrationClosureUser');
 
         $user = new HydrationClosureUser();
         $this->dm->getHydratorFactory()->hydrate($user, [
@@ -56,7 +54,7 @@ public function testReadOnly()
             'birthdate' => new \DateTime('1961-01-01'),
             'embedOne' => ['name' => 'maciej'],
             'embedMany' => [
-                ['name' => 'maciej']
+                ['name' => 'maciej'],
             ],
         ], [ Query::HINT_READ_ONLY => true ]);
 
@@ -85,13 +83,13 @@ class HydrationClosureUser
     public $referenceOne;
 
     /** @ODM\ReferenceMany(targetDocument="HydrationClosureReferenceMany") */
-    public $referenceMany = array();
+    public $referenceMany = [];
 
     /** @ODM\EmbedOne(targetDocument="HydrationClosureEmbedOne") */
     public $embedOne;
 
     /** @ODM\EmbedMany(targetDocument="HydrationClosureEmbedMany") */
-    public $embedMany = array();
+    public $embedMany = [];
 }
 
 /** @ODM\Document */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Id/IncrementGeneratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Id/IncrementGeneratorTest.php
index 523b197442..68c933ce96 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Id/IncrementGeneratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Id/IncrementGeneratorTest.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Id;
 
 use Doctrine\ODM\MongoDB\Id\IncrementGenerator;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\User;
+use const DOCTRINE_MONGODB_DATABASE;
 
-class IncrementGeneratorTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class IncrementGeneratorTest extends BaseTest
 {
     public function testIdGeneratorWithStartingValue()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
index 6df5f080f8..0efc6447b5 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
@@ -1,11 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function key;
+use function strcmp;
+use function usort;
 
-abstract class AbstractMappingDriverTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+abstract class AbstractMappingDriverTest extends BaseTest
 {
     abstract protected function _loadDriver();
 
@@ -14,7 +21,7 @@ abstract protected function _loadDriver();
      */
     public function testLoadMapping()
     {
-        $className = __NAMESPACE__.'\AbstractMappingDriverUser';
+        $className = __NAMESPACE__ . '\AbstractMappingDriverUser';
         $mappingDriver = $this->_loadDriver();
 
         $class = new ClassMetadata($className);
@@ -52,7 +59,7 @@ public function testDocumentMarkedAsReadOnly($class)
      */
     public function testDocumentLevelReadPreference($class)
     {
-        $this->assertEquals("primaryPreferred", $class->readPreference);
+        $this->assertEquals('primaryPreferred', $class->readPreference);
         $this->assertEquals([
             ['dc' => 'east'],
             ['dc' => 'west'],
@@ -164,9 +171,9 @@ public function testVersionFieldMappings($class)
     }
 
     /**
-    * @depends testFieldMappings
-    * @param ClassMetadata $class
-    */
+     * @depends testFieldMappings
+     * @param ClassMetadata $class
+     */
     public function testLockFieldMappings($class)
     {
         $this->assertEquals('int', $class->fieldMappings['lock']['type']);
@@ -210,10 +217,10 @@ public function testOwningOneToOneAssocation($class)
      */
     public function testLifecycleCallbacks($class)
     {
-        $expectedLifecycleCallbacks = array(
-            'prePersist' => array('doStuffOnPrePersist', 'doOtherStuffOnPrePersistToo'),
-            'postPersist' => array('doStuffOnPostPersist'),
-        );
+        $expectedLifecycleCallbacks = [
+            'prePersist' => ['doStuffOnPrePersist', 'doOtherStuffOnPrePersistToo'],
+            'postPersist' => ['doStuffOnPostPersist'],
+        ];
 
         $this->assertEquals($expectedLifecycleCallbacks, $class->lifecycleCallbacks);
 
@@ -266,9 +273,7 @@ public function testDiscriminator($class)
         $this->assertTrue(isset($class->discriminatorMap));
         $this->assertTrue(isset($class->defaultDiscriminatorValue));
         $this->assertEquals('discr', $class->discriminatorField);
-        $this->assertEquals(array(
-            'default' => 'Doctrine\ODM\MongoDB\Tests\Mapping\AbstractMappingDriverUser',
-        ), $class->discriminatorMap);
+        $this->assertEquals(['default' => 'Doctrine\ODM\MongoDB\Tests\Mapping\AbstractMappingDriverUser'], $class->discriminatorMap);
         $this->assertEquals('default', $class->defaultDiscriminatorValue);
 
         return $class;
@@ -284,10 +289,10 @@ public function testEmbedDiscriminator($class)
         $this->assertTrue(isset($class->fieldMappings['otherPhonenumbers']['discriminatorMap']));
         $this->assertTrue(isset($class->fieldMappings['otherPhonenumbers']['defaultDiscriminatorValue']));
         $this->assertEquals('discr', $class->fieldMappings['otherPhonenumbers']['discriminatorField']);
-        $this->assertEquals(array(
+        $this->assertEquals([
             'home' => 'Doctrine\ODM\MongoDB\Tests\Mapping\HomePhonenumber',
-            'work' => 'Doctrine\ODM\MongoDB\Tests\Mapping\WorkPhonenumber'
-        ), $class->fieldMappings['otherPhonenumbers']['discriminatorMap']);
+            'work' => 'Doctrine\ODM\MongoDB\Tests\Mapping\WorkPhonenumber',
+        ], $class->fieldMappings['otherPhonenumbers']['discriminatorMap']);
         $this->assertEquals('home', $class->fieldMappings['otherPhonenumbers']['defaultDiscriminatorValue']);
 
         return $class;
@@ -303,10 +308,10 @@ public function testReferenceDiscriminator($class)
         $this->assertTrue(isset($class->fieldMappings['phonenumbers']['discriminatorMap']));
         $this->assertTrue(isset($class->fieldMappings['phonenumbers']['defaultDiscriminatorValue']));
         $this->assertEquals('discr', $class->fieldMappings['phonenumbers']['discriminatorField']);
-        $this->assertEquals(array(
+        $this->assertEquals([
             'home' => 'Doctrine\ODM\MongoDB\Tests\Mapping\HomePhonenumber',
-            'work' => 'Doctrine\ODM\MongoDB\Tests\Mapping\WorkPhonenumber'
-        ), $class->fieldMappings['phonenumbers']['discriminatorMap']);
+            'work' => 'Doctrine\ODM\MongoDB\Tests\Mapping\WorkPhonenumber',
+        ], $class->fieldMappings['phonenumbers']['discriminatorMap']);
         $this->assertEquals('home', $class->fieldMappings['phonenumbers']['defaultDiscriminatorValue']);
 
         return $class;
@@ -323,7 +328,7 @@ public function testIndexes($class)
         /* Sort indexes by their first fieldname. This is necessary since the
          * index registration order may differ among drivers.
          */
-        $this->assertTrue(usort($indexes, function(array $a, array $b) {
+        $this->assertTrue(usort($indexes, function (array $a, array $b) {
             return strcmp(key($a['keys']), key($b['keys']));
         }));
 
@@ -345,7 +350,7 @@ public function testIndexes($class)
         $this->assertEquals(1, $indexes[2]['keys']['lock']);
         $this->assertNotEmpty($indexes[2]['options']);
         $this->assertTrue(isset($indexes[2]['options']['partialFilterExpression']));
-        $this->assertSame(array('version' => array('$gt' => 1), 'discr' => array('$eq' => 'default')), $indexes[2]['options']['partialFilterExpression']);
+        $this->assertSame(['version' => ['$gt' => 1], 'discr' => ['$eq' => 'default']], $indexes[2]['options']['partialFilterExpression']);
 
         $this->assertTrue(isset($indexes[3]['keys']['mysqlProfileId']));
         $this->assertEquals(-1, $indexes[3]['keys']['mysqlProfileId']);
@@ -472,7 +477,7 @@ class AbstractMappingDriverUser
     /**
      * @ODM\Field(type="collection")
      */
-    public $roles = array();
+    public $roles = [];
 
     /**
      * @ODM\PrePersist
@@ -502,97 +507,92 @@ public static function loadMetadata(ClassMetadata $metadata)
         $metadata->addLifecycleCallback('doStuffOnPrePersist', 'prePersist');
         $metadata->addLifecycleCallback('doOtherStuffOnPrePersistToo', 'prePersist');
         $metadata->addLifecycleCallback('doStuffOnPostPersist', 'postPersist');
-        $metadata->setDiscriminatorField(array(
-            'fieldName' => 'discr',
-        ));
-        $metadata->setDiscriminatorMap(array(
-            'default' => __CLASS__,
-        ));
+        $metadata->setDiscriminatorField(['fieldName' => 'discr']);
+        $metadata->setDiscriminatorMap(['default' => __CLASS__]);
         $metadata->setDefaultDiscriminatorValue('default');
-        $metadata->mapField(array(
+        $metadata->mapField([
             'id' => true,
             'fieldName' => 'id',
-        ));
-        $metadata->mapField(array(
+        ]);
+        $metadata->mapField([
             'fieldName' => 'version',
             'type' => 'int',
             'version' => true,
-        ));
-        $metadata->mapField(array(
+        ]);
+        $metadata->mapField([
             'fieldName' => 'lock',
             'type' => 'int',
             'lock' => true,
-        ));
-        $metadata->mapField(array(
+        ]);
+        $metadata->mapField([
             'fieldName' => 'name',
             'name' => 'username',
             'type' => 'string',
-        ));
-        $metadata->mapField(array(
+        ]);
+        $metadata->mapField([
             'fieldName' => 'email',
             'type' => 'string',
-        ));
-        $metadata->mapField(array(
+        ]);
+        $metadata->mapField([
             'fieldName' => 'mysqlProfileId',
             'type' => 'integer',
-        ));
-        $metadata->mapOneReference(array(
+        ]);
+        $metadata->mapOneReference([
             'fieldName' => 'address',
             'targetDocument' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\Address',
-            'cascade' => array(0 => 'remove'),
-        ));
-        $metadata->mapManyReference(array(
+            'cascade' => [0 => 'remove'],
+        ]);
+        $metadata->mapManyReference([
             'fieldName' => 'phonenumbers',
             'targetDocument' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\Phonenumber',
             'collectionClass' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\PhonenumberCollection',
-            'cascade' => array(1 => 'persist'),
+            'cascade' => [1 => 'persist'],
             'discriminatorField' => 'discr',
-            'discriminatorMap' => array(
+            'discriminatorMap' => [
                 'home' => 'HomePhonenumber',
-                'work' => 'WorkPhonenumber'
-            ),
+                'work' => 'WorkPhonenumber',
+            ],
             'defaultDiscriminatorValue' => 'home',
-        ));
-        $metadata->mapManyReference(array(
+        ]);
+        $metadata->mapManyReference([
             'fieldName' => 'morePhoneNumbers',
             'name' => 'more_phone_numbers',
             'targetDocument' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\Phonenumber',
             'collectionClass' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\PhonenumberCollection',
-        ));
-        $metadata->mapManyReference(array(
+        ]);
+        $metadata->mapManyReference([
             'fieldName' => 'groups',
             'targetDocument' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\Group',
-            'cascade' => array(
+            'cascade' => [
                 0 => 'remove',
                 1 => 'persist',
                 2 => 'refresh',
                 3 => 'merge',
                 4 => 'detach',
-            ),
-        ));
-        $metadata->mapOneEmbedded(array(
+            ],
+        ]);
+        $metadata->mapOneEmbedded([
            'fieldName' => 'embeddedPhonenumber',
            'name' => 'embedded_phone_number',
-        ));
-        $metadata->mapManyEmbedded(array(
+        ]);
+        $metadata->mapManyEmbedded([
            'fieldName' => 'otherPhonenumbers',
            'targetDocument' => 'Doctrine\\ODM\\MongoDB\\Tests\\Mapping\\Phonenumber',
            'discriminatorField' => 'discr',
-           'discriminatorMap' => array(
+           'discriminatorMap' => [
                 'home' => 'HomePhonenumber',
                 'work' => 'WorkPhonenumber',
-           ),
+           ],
             'defaultDiscriminatorValue' => 'home',
-        ));
-        $metadata->addIndex(array('username' => 'desc'), array('unique' => true, 'dropDups' => false));
-        $metadata->addIndex(array('email' => 'desc'), array('unique' => true, 'dropDups' => true));
-        $metadata->addIndex(array('mysqlProfileId' => 'desc'), array('unique' => true, 'dropDups' => true));
-        $metadata->addIndex(array('createdAt' => 'asc'), array('expireAfterSeconds' => 3600));
-        $metadata->setShardKey(array('name' => 'asc'), array('unique' => true, 'numInitialChunks' => 4096));
+        ]);
+        $metadata->addIndex(['username' => 'desc'], ['unique' => true, 'dropDups' => false]);
+        $metadata->addIndex(['email' => 'desc'], ['unique' => true, 'dropDups' => true]);
+        $metadata->addIndex(['mysqlProfileId' => 'desc'], ['unique' => true, 'dropDups' => true]);
+        $metadata->addIndex(['createdAt' => 'asc'], ['expireAfterSeconds' => 3600]);
+        $metadata->setShardKey(['name' => 'asc'], ['unique' => true, 'numInitialChunks' => 4096]);
     }
 }
 
-class PhonenumberCollection extends \Doctrine\Common\Collections\ArrayCollection
+class PhonenumberCollection extends ArrayCollection
 {
-
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AnnotationDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AnnotationDriverTest.php
index 356401ca82..fa11fe2a20 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AnnotationDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AnnotationDriverTest.php
@@ -1,9 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\Common\Annotations\AnnotationReader;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
+use Doctrine\ODM\MongoDB\Mapping\MappingException;
 
 class AnnotationDriverTest extends AbstractMappingDriverTest
 {
@@ -65,10 +70,10 @@ public function testFieldInheritance()
     public function testLoadMetadataForNonDocumentThrowsException()
     {
         $cm = new ClassMetadata('stdClass');
-        $reader = new \Doctrine\Common\Annotations\AnnotationReader();
-        $annotationDriver = new \Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver($reader);
+        $reader = new AnnotationReader();
+        $annotationDriver = new AnnotationDriver($reader);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\Mapping\MappingException::class);
+        $this->expectException(MappingException::class);
         $annotationDriver->loadMetadataForClass('stdClass', $cm);
     }
 
@@ -78,8 +83,8 @@ public function testLoadMetadataForNonDocumentThrowsException()
     public function testColumnWithMissingTypeDefaultsToString()
     {
         $cm = new ClassMetadata('Doctrine\ODM\MongoDB\Tests\Mapping\ColumnWithoutType');
-        $reader = new \Doctrine\Common\Annotations\AnnotationReader();
-        $annotationDriver = new \Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver($reader);
+        $reader = new AnnotationReader();
+        $annotationDriver = new AnnotationDriver($reader);
 
         $annotationDriver->loadMetadataForClass('Doctrine\ODM\MongoDB\Tests\Mapping\InvalidColumn', $cm);
         $this->assertEquals('id', $cm->fieldMappings['id']['type']);
@@ -163,14 +168,14 @@ public function testDocumentAnnotationCanSpecifyWriteConcern()
     protected function _loadDriverForCMSDocuments()
     {
         $annotationDriver = $this->_loadDriver();
-        $annotationDriver->addPaths(array(__DIR__ . '/../../../../../Documents'));
+        $annotationDriver->addPaths([__DIR__ . '/../../../../../Documents']);
         return $annotationDriver;
     }
 
     protected function _loadDriver()
     {
-        $reader = new \Doctrine\Common\Annotations\AnnotationReader();
-        return new \Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver($reader);
+        $reader = new AnnotationReader();
+        return new AnnotationDriver($reader);
     }
 }
 
@@ -178,7 +183,7 @@ protected function _loadDriver()
 class ColumnWithoutType
 {
      /** @ODM\Id */
-     public $id;
+    public $id;
 }
 
 /** @ODM\MappedSuperclass */
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/BasicInheritanceMappingTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/BasicInheritanceMappingTest.php
index bf69fd9d15..c12afc0ce4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/BasicInheritanceMappingTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/BasicInheritanceMappingTest.php
@@ -1,11 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use function serialize;
+use function unserialize;
 
-class BasicInheritanceMappingTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class BasicInheritanceMappingTest extends BaseTest
 {
     private $factory;
 
@@ -72,7 +77,7 @@ public function testReadPreferenceIsInherited()
     {
         $class = $this->factory->getMetadataFor(DocumentSubClass2::class);
 
-        $this->assertSame("secondary", $class->readPreference);
+        $this->assertSame('secondary', $class->readPreference);
         $this->assertEquals([ ['dc' => 'east'] ], $class->readPreferenceTags);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataFactoryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataFactoryTest.php
index 8a1c6a1bac..ab0ab66593 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataFactoryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataFactoryTest.php
@@ -1,114 +1,116 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\Mapping;
-
-use Doctrine\ODM\MongoDB\Configuration;
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
-use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
-use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
-use Doctrine\ODM\MongoDB\Tests\Mocks\DocumentManagerMock;
-
-class ClassMetadataFactoryTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
-{
-    public function testGetMetadataForSingleClass()
-    {
-        // Self-made metadata
-        $cm1 = new ClassMetadata('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1');
-        $cm1->setCollection('group');
-        // Add a mapped field
-        $cm1->mapField(array('fieldName' => 'name', 'type' => 'string'));
-        // Add a mapped field
-        $cm1->mapField(array('fieldName' => 'id', 'id' => true));
-        // and a mapped association
-        $cm1->mapOneEmbedded(array('fieldName' => 'other', 'targetDocument' => 'Other'));
-        $cm1->mapOneEmbedded(array('fieldName' => 'association', 'targetDocument' => 'Other'));
-
-        // SUT
-        $cmf = new ClassMetadataFactoryTestSubject();
-        $cmf->setMetadataFor('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1', $cm1);
-
-        // Prechecks
-        $this->assertEquals(array(), $cm1->parentClasses);
-        $this->assertEquals(ClassMetadata::INHERITANCE_TYPE_NONE, $cm1->inheritanceType);
-        $this->assertTrue($cm1->hasField('name'));
-        $this->assertCount(4, $cm1->fieldMappings);
-
-        // Go
-        $cm1 = $cmf->getMetadataFor('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1');
-
-        $this->assertEquals('group', $cm1->collection);
-        $this->assertEquals(array(), $cm1->parentClasses);
-        $this->assertTrue($cm1->hasField('name'));
-    }
-
-    public function testHasGetMetadata_NamespaceSeperatorIsNotNormalized()
-    {
-        require_once __DIR__."/Documents/GlobalNamespaceDocument.php";
-
-        $driver = AnnotationDriver::create(__DIR__ . '/Documents');
-
-        $dm = $this->getMockDocumentManager($driver);
-
-        $cmf = new ClassMetadataFactory();
-        $cmf->setConfiguration($dm->getConfiguration());
-        $cmf->setDocumentManager($dm);
-
-        $m1 = $cmf->getMetadataFor("DoctrineGlobal_Article");
-        $h1 = $cmf->hasMetadataFor("DoctrineGlobal_Article");
-        $h2 = $cmf->hasMetadataFor("\DoctrineGlobal_Article");
-        $m2 = $cmf->getMetadataFor("\DoctrineGlobal_Article");
-
-        $this->assertNotSame($m1, $m2);
-        $this->assertFalse($h2);
-        $this->assertTrue($h1);
-    }
-
-    protected function getMockDocumentManager($driver)
-    {
-        $config = new Configuration();
-        $config->setMetadataDriverImpl($driver);
-
-        $em = $this->createMock('Doctrine\Common\EventManager');
-
-        $dm = new DocumentManagerMock();
-        $dm->config = $config;
-        $dm->eventManager = $em;
-
-        return $dm;
-    }
-}
-
-/* Test subject class with overriden factory method for mocking purposes */
-class ClassMetadataFactoryTestSubject extends \Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory
-{
-    private $_mockMetadata = array();
-    private $_requestedClasses = array();
-
-    /** @override */
-    protected function _newClassMetadataInstance($className)
-    {
-        $this->_requestedClasses[] = $className;
-        if ( ! isset($this->_mockMetadata[$className])) {
-            throw new InvalidArgumentException("No mock metadata found for class $className.");
-        }
-        return $this->_mockMetadata[$className];
-    }
-
-    public function setMetadataForClass($className, $metadata)
-    {
-        $this->_mockMetadata[$className] = $metadata;
-    }
-
-    public function getRequestedClasses()
-    {
-        return $this->_requestedClasses;
-    }
-}
-
-class TestDocument1
-{
-    private $id;
-    private $name;
-    private $other;
-    private $association;
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\Mapping;
+
+use Doctrine\ODM\MongoDB\Configuration;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
+use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Doctrine\ODM\MongoDB\Tests\Mocks\DocumentManagerMock;
+
+class ClassMetadataFactoryTest extends BaseTest
+{
+    public function testGetMetadataForSingleClass()
+    {
+        // Self-made metadata
+        $cm1 = new ClassMetadata('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1');
+        $cm1->setCollection('group');
+        // Add a mapped field
+        $cm1->mapField(['fieldName' => 'name', 'type' => 'string']);
+        // Add a mapped field
+        $cm1->mapField(['fieldName' => 'id', 'id' => true]);
+        // and a mapped association
+        $cm1->mapOneEmbedded(['fieldName' => 'other', 'targetDocument' => 'Other']);
+        $cm1->mapOneEmbedded(['fieldName' => 'association', 'targetDocument' => 'Other']);
+
+        // SUT
+        $cmf = new ClassMetadataFactoryTestSubject();
+        $cmf->setMetadataFor('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1', $cm1);
+
+        // Prechecks
+        $this->assertEquals([], $cm1->parentClasses);
+        $this->assertEquals(ClassMetadata::INHERITANCE_TYPE_NONE, $cm1->inheritanceType);
+        $this->assertTrue($cm1->hasField('name'));
+        $this->assertCount(4, $cm1->fieldMappings);
+
+        // Go
+        $cm1 = $cmf->getMetadataFor('Doctrine\ODM\MongoDB\Tests\Mapping\TestDocument1');
+
+        $this->assertEquals('group', $cm1->collection);
+        $this->assertEquals([], $cm1->parentClasses);
+        $this->assertTrue($cm1->hasField('name'));
+    }
+
+    public function testHasGetMetadata_NamespaceSeperatorIsNotNormalized()
+    {
+        require_once __DIR__ . '/Documents/GlobalNamespaceDocument.php';
+
+        $driver = AnnotationDriver::create(__DIR__ . '/Documents');
+
+        $dm = $this->getMockDocumentManager($driver);
+
+        $cmf = new ClassMetadataFactory();
+        $cmf->setConfiguration($dm->getConfiguration());
+        $cmf->setDocumentManager($dm);
+
+        $m1 = $cmf->getMetadataFor('DoctrineGlobal_Article');
+        $h1 = $cmf->hasMetadataFor('DoctrineGlobal_Article');
+        $h2 = $cmf->hasMetadataFor('\DoctrineGlobal_Article');
+        $m2 = $cmf->getMetadataFor('\DoctrineGlobal_Article');
+
+        $this->assertNotSame($m1, $m2);
+        $this->assertFalse($h2);
+        $this->assertTrue($h1);
+    }
+
+    protected function getMockDocumentManager($driver)
+    {
+        $config = new Configuration();
+        $config->setMetadataDriverImpl($driver);
+
+        $em = $this->createMock('Doctrine\Common\EventManager');
+
+        $dm = new DocumentManagerMock();
+        $dm->config = $config;
+        $dm->eventManager = $em;
+
+        return $dm;
+    }
+}
+
+/* Test subject class with overriden factory method for mocking purposes */
+class ClassMetadataFactoryTestSubject extends ClassMetadataFactory
+{
+    private $_mockMetadata = [];
+    private $_requestedClasses = [];
+
+    protected function _newClassMetadataInstance($className)
+    {
+        $this->_requestedClasses[] = $className;
+        if (! isset($this->_mockMetadata[$className])) {
+            throw new InvalidArgumentException("No mock metadata found for class $className.");
+        }
+        return $this->_mockMetadata[$className];
+    }
+
+    public function setMetadataForClass($className, $metadata)
+    {
+        $this->_mockMetadata[$className] = $metadata;
+    }
+
+    public function getRequestedClasses()
+    {
+        return $this->_requestedClasses;
+    }
+}
+
+class TestDocument1
+{
+    private $id;
+    private $name;
+    private $other;
+    private $association;
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataLoadEventTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataLoadEventTest.php
index 2ca3a00e8a..353e2df936 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataLoadEventTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataLoadEventTest.php
@@ -1,11 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
+use Doctrine\ODM\MongoDB\Event\LoadClassMetadataEventArgs;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
-class ClassMetadataLoadEventTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ClassMetadataLoadEventTest extends BaseTest
 {
     public function testEvent()
     {
@@ -16,13 +20,13 @@ public function testEvent()
         $this->assertTrue($classMetadata->hasField('about'));
     }
 
-    public function loadClassMetadata(\Doctrine\ODM\MongoDB\Event\LoadClassMetadataEventArgs $eventArgs)
+    public function loadClassMetadata(LoadClassMetadataEventArgs $eventArgs)
     {
         $classMetadata = $eventArgs->getClassMetadata();
-        $field = array(
+        $field = [
             'fieldName' => 'about',
-            'type' => 'string'
-        );
+            'type' => 'string',
+        ];
         $classMetadata->mapField($field);
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataTest.php
index e046acadbf..25619075c4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ClassMetadataTest.php
@@ -1,19 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
 use Doctrine\ODM\MongoDB\Events;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Mapping\MappingException;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Utility\CollectionHelper;
 use Documents\Account;
 use Documents\Album;
 use Documents\CmsUser;
 use Documents\SpecialUser;
 use Documents\User;
+use function array_merge;
+use function get_class;
+use function serialize;
+use function unserialize;
 
-class ClassMetadataTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ClassMetadataTest extends BaseTest
 {
     public function testClassMetadataInstanceSerialization()
     {
@@ -24,18 +32,18 @@ public function testClassMetadataInstanceSerialization()
         $this->assertInstanceOf(\ReflectionClass::class, $cm->reflClass);
         $this->assertEquals('Documents\CmsUser', $cm->name);
         $this->assertEquals('Documents\CmsUser', $cm->rootDocumentName);
-        $this->assertEquals(array(), $cm->subClasses);
-        $this->assertEquals(array(), $cm->parentClasses);
+        $this->assertEquals([], $cm->subClasses);
+        $this->assertEquals([], $cm->parentClasses);
         $this->assertEquals(ClassMetadata::INHERITANCE_TYPE_NONE, $cm->inheritanceType);
 
         // Customize state
         $cm->setInheritanceType(ClassMetadata::INHERITANCE_TYPE_SINGLE_COLLECTION);
-        $cm->setSubclasses(array("One", "Two", "Three"));
-        $cm->setParentClasses(array("UserParent"));
-        $cm->setCustomRepositoryClass("UserRepository");
+        $cm->setSubclasses(['One', 'Two', 'Three']);
+        $cm->setParentClasses(['UserParent']);
+        $cm->setCustomRepositoryClass('UserRepository');
         $cm->setDiscriminatorField('disc');
-        $cm->mapOneEmbedded(array('fieldName' => 'phonenumbers', 'targetDocument' => 'Bar'));
-        $cm->setShardKey(array('_id' => '1'));
+        $cm->mapOneEmbedded(['fieldName' => 'phonenumbers', 'targetDocument' => 'Bar']);
+        $cm->setShardKey(['_id' => '1']);
         $cm->setCollectionCapped(true);
         $cm->setCollectionMax(1000);
         $cm->setCollectionSize(500);
@@ -52,14 +60,14 @@ public function testClassMetadataInstanceSerialization()
         $this->assertInstanceOf(\ReflectionClass::class, $cm->reflClass);
         $this->assertEquals('Documents\CmsUser', $cm->name);
         $this->assertEquals('UserParent', $cm->rootDocumentName);
-        $this->assertEquals(array('Documents\One', 'Documents\Two', 'Documents\Three'), $cm->subClasses);
-        $this->assertEquals(array('UserParent'), $cm->parentClasses);
+        $this->assertEquals(['Documents\One', 'Documents\Two', 'Documents\Three'], $cm->subClasses);
+        $this->assertEquals(['UserParent'], $cm->parentClasses);
         $this->assertEquals('Documents\UserRepository', $cm->customRepositoryClassName);
         $this->assertEquals('disc', $cm->discriminatorField);
         $this->assertInternalType('array', $cm->getFieldMapping('phonenumbers'));
         $this->assertCount(1, $cm->fieldMappings);
         $this->assertCount(1, $cm->associationMappings);
-        $this->assertEquals(array('keys' => array('_id' => 1), 'options' => array()), $cm->getShardKey());
+        $this->assertEquals(['keys' => ['_id' => 1], 'options' => []], $cm->getShardKey());
         $mapping = $cm->getFieldMapping('phonenumbers');
         $this->assertEquals('Documents\Bar', $mapping['targetDocument']);
         $this->assertTrue($cm->getCollectionCapped());
@@ -70,11 +78,11 @@ public function testClassMetadataInstanceSerialization()
     public function testOwningSideAndInverseSide()
     {
         $cm = new ClassMetadata(User::class);
-        $cm->mapOneReference(array('fieldName' => 'account', 'targetDocument' => Account::class, 'inversedBy' => 'user'));
+        $cm->mapOneReference(['fieldName' => 'account', 'targetDocument' => Account::class, 'inversedBy' => 'user']);
         $this->assertTrue($cm->fieldMappings['account']['isOwningSide']);
 
         $cm = new ClassMetadata(Account::class);
-        $cm->mapOneReference(array('fieldName' => 'user', 'targetDocument' => Account::class, 'mappedBy' => 'account'));
+        $cm->mapOneReference(['fieldName' => 'user', 'targetDocument' => Account::class, 'mappedBy' => 'account']);
         $this->assertTrue($cm->fieldMappings['user']['isInverseSide']);
     }
 
@@ -83,16 +91,16 @@ public function testFieldIsNullable()
         $cm = new ClassMetadata('Documents\CmsUser');
 
         // Explicit Nullable
-        $cm->mapField(array('fieldName' => 'status', 'nullable' => true, 'type' => 'string', 'length' => 50));
+        $cm->mapField(['fieldName' => 'status', 'nullable' => true, 'type' => 'string', 'length' => 50]);
         $this->assertTrue($cm->isNullable('status'));
 
         // Explicit Not Nullable
-        $cm->mapField(array('fieldName' => 'username', 'nullable' => false, 'type' => 'string', 'length' => 50));
+        $cm->mapField(['fieldName' => 'username', 'nullable' => false, 'type' => 'string', 'length' => 50]);
         $this->assertFalse($cm->isNullable('username'));
 
         // Implicit Not Nullable
-        $cm->mapField(array('fieldName' => 'name', 'type' => 'string', 'length' => 50));
-        $this->assertFalse($cm->isNullable('name'), "By default a field should not be nullable.");
+        $cm->mapField(['fieldName' => 'name', 'type' => 'string', 'length' => 50]);
+        $this->assertFalse($cm->isNullable('name'), 'By default a field should not be nullable.');
     }
 
     /**
@@ -100,25 +108,26 @@ public function testFieldIsNullable()
      */
     public function testMapAssocationInGlobalNamespace()
     {
-        require_once __DIR__."/Documents/GlobalNamespaceDocument.php";
+        require_once __DIR__ . '/Documents/GlobalNamespaceDocument.php';
 
         $cm = new ClassMetadata('DoctrineGlobal_Article');
-        $cm->mapManyEmbedded(array(
+        $cm->mapManyEmbedded([
             'fieldName' => 'author',
             'targetDocument' => 'DoctrineGlobal_User',
-        ));
+        ]);
 
-        $this->assertEquals("DoctrineGlobal_User", $cm->fieldMappings['author']['targetDocument']);
+        $this->assertEquals('DoctrineGlobal_User', $cm->fieldMappings['author']['targetDocument']);
     }
 
     public function testMapManyToManyJoinTableDefaults()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
         $cm->mapManyEmbedded(
-            array(
+            [
             'fieldName' => 'groups',
-            'targetDocument' => 'CmsGroup'
-        ));
+            'targetDocument' => 'CmsGroup',
+            ]
+        );
 
         $assoc = $cm->fieldMappings['groups'];
         $this->assertInternalType('array', $assoc);
@@ -129,13 +138,13 @@ public function testMapManyToManyJoinTableDefaults()
      */
     public function testSetDiscriminatorMapInGlobalNamespace()
     {
-        require_once __DIR__."/Documents/GlobalNamespaceDocument.php";
+        require_once __DIR__ . '/Documents/GlobalNamespaceDocument.php';
 
         $cm = new ClassMetadata('DoctrineGlobal_User');
-        $cm->setDiscriminatorMap(array('descr' => 'DoctrineGlobal_Article', 'foo' => 'DoctrineGlobal_User'));
+        $cm->setDiscriminatorMap(['descr' => 'DoctrineGlobal_Article', 'foo' => 'DoctrineGlobal_User']);
 
-        $this->assertEquals("DoctrineGlobal_Article", $cm->discriminatorMap['descr']);
-        $this->assertEquals("DoctrineGlobal_User", $cm->discriminatorMap['foo']);
+        $this->assertEquals('DoctrineGlobal_Article', $cm->discriminatorMap['descr']);
+        $this->assertEquals('DoctrineGlobal_User', $cm->discriminatorMap['foo']);
     }
 
     /**
@@ -143,19 +152,19 @@ public function testSetDiscriminatorMapInGlobalNamespace()
      */
     public function testSetSubClassesInGlobalNamespace()
     {
-        require_once __DIR__."/Documents/GlobalNamespaceDocument.php";
+        require_once __DIR__ . '/Documents/GlobalNamespaceDocument.php';
 
         $cm = new ClassMetadata('DoctrineGlobal_User');
-        $cm->setSubclasses(array('DoctrineGlobal_Article'));
+        $cm->setSubclasses(['DoctrineGlobal_Article']);
 
-        $this->assertEquals("DoctrineGlobal_Article", $cm->subClasses[0]);
+        $this->assertEquals('DoctrineGlobal_Article', $cm->subClasses[0]);
     }
 
     public function testDuplicateFieldMapping()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
-        $a1 = array('reference' => true, 'type' => 'many', 'fieldName' => 'name', 'targetDocument' => 'stdClass');
-        $a2 = array('type' => 'string', 'fieldName' => 'name');
+        $a1 = ['reference' => true, 'type' => 'many', 'fieldName' => 'name', 'targetDocument' => 'stdClass'];
+        $a2 = ['type' => 'string', 'fieldName' => 'name'];
 
         $cm->mapField($a1);
         $cm->mapField($a2);
@@ -166,9 +175,9 @@ public function testDuplicateFieldMapping()
     public function testDuplicateColumnName_DiscriminatorColumn_ThrowsMappingException()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
-        $cm->mapField(array('fieldName' => 'name'));
+        $cm->mapField(['fieldName' => 'name']);
 
-        $this->expectException(\Doctrine\ODM\MongoDB\Mapping\MappingException::class);
+        $this->expectException(MappingException::class);
         $cm->setDiscriminatorField('name');
     }
 
@@ -177,15 +186,15 @@ public function testDuplicateFieldName_DiscriminatorColumn2_ThrowsMappingExcepti
         $cm = new ClassMetadata('Documents\CmsUser');
         $cm->setDiscriminatorField('name');
 
-        $this->expectException(\Doctrine\ODM\MongoDB\Mapping\MappingException::class);
-        $cm->mapField(array('fieldName' => 'name'));
+        $this->expectException(MappingException::class);
+        $cm->mapField(['fieldName' => 'name']);
     }
 
     public function testDuplicateFieldAndAssocationMapping1()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
-        $cm->mapField(array('fieldName' => 'name'));
-        $cm->mapOneEmbedded(array('fieldName' => 'name', 'targetDocument' => 'CmsUser'));
+        $cm->mapField(['fieldName' => 'name']);
+        $cm->mapOneEmbedded(['fieldName' => 'name', 'targetDocument' => 'CmsUser']);
 
         $this->assertEquals('one', $cm->fieldMappings['name']['type']);
     }
@@ -193,8 +202,8 @@ public function testDuplicateFieldAndAssocationMapping1()
     public function testDuplicateFieldAndAssocationMapping2()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
-        $cm->mapOneEmbedded(array('fieldName' => 'name', 'targetDocument' => 'CmsUser'));
-        $cm->mapField(array('fieldName' => 'name', 'columnName' => 'name', 'type' => 'string'));
+        $cm->mapOneEmbedded(['fieldName' => 'name', 'targetDocument' => 'CmsUser']);
+        $cm->mapField(['fieldName' => 'name', 'columnName' => 'name', 'type' => 'string']);
 
         $this->assertEquals('string', $cm->fieldMappings['name']['type']);
     }
@@ -205,11 +214,10 @@ public function testDuplicateFieldAndAssocationMapping2()
     public function testMapNotExistingFieldThrowsException()
     {
         $cm = new ClassMetadata('Documents\CmsUser');
-        $cm->mapField(array('fieldName' => 'namee', 'columnName' => 'name', 'type' => 'string'));
+        $cm->mapField(['fieldName' => 'namee', 'columnName' => 'name', 'type' => 'string']);
     }
 
     /**
-     * @param ClassMetadata $cm
      * @dataProvider dataProviderMetadataClasses
      */
     public function testEmbeddedDocumentWithDiscriminator(ClassMetadata $cm)
@@ -251,44 +259,47 @@ public function testDefaultDiscriminatorField()
 
         $cm = new ClassMetadata(get_class($object));
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'one',
-        ));
+        ]);
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assocWithTargetDocument',
             'reference' => true,
             'type' => 'one',
             'targetDocument' => 'stdClass',
-        ));
+        ]);
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assocWithDiscriminatorField',
             'reference' => true,
             'type' => 'one',
             'discriminatorField' => 'type',
-        ));
+        ]);
 
         $mapping = $cm->getFieldMapping('assoc');
 
         $this->assertEquals(
-            ClassMetadata::DEFAULT_DISCRIMINATOR_FIELD, $mapping['discriminatorField'],
+            ClassMetadata::DEFAULT_DISCRIMINATOR_FIELD,
+            $mapping['discriminatorField'],
             'Default discriminator field is set for associations without targetDocument and discriminatorField options'
         );
 
         $mapping = $cm->getFieldMapping('assocWithTargetDocument');
 
         $this->assertArrayNotHasKey(
-            'discriminatorField', $mapping,
+            'discriminatorField',
+            $mapping,
             'Default discriminator field is not set for associations with targetDocument option'
         );
 
         $mapping = $cm->getFieldMapping('assocWithDiscriminatorField');
 
         $this->assertEquals(
-            'type', $mapping['discriminatorField'],
+            'type',
+            $mapping['discriminatorField'],
             'Default discriminator field is not set for associations with discriminatorField option'
         );
     }
@@ -401,11 +412,11 @@ public function testEmbeddedAssociationsAlwaysCascade()
     public function testEmbedWithCascadeThrowsMappingException()
     {
         $class = new ClassMetadata(__NAMESPACE__ . '\EmbedWithCascadeTest');
-        $class->mapOneEmbedded(array(
+        $class->mapOneEmbedded([
             'fieldName' => 'address',
             'targetDocument' => 'Documents\Address',
             'cascade' => 'all',
-        ));
+        ]);
     }
 
     /**
@@ -455,12 +466,12 @@ public function testSimpleReferenceRequiresTargetDocument()
     {
         $cm = new ClassMetadata('stdClass');
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'one',
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_ID,
-        ));
+        ]);
     }
 
     /**
@@ -471,12 +482,12 @@ public function testSimpleAsStringReferenceRequiresTargetDocument()
     {
         $cm = new ClassMetadata('stdClass');
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'one',
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_ID,
-        ));
+        ]);
     }
 
     /**
@@ -487,12 +498,12 @@ public function testStoreAsIdReferenceRequiresTargetDocument()
     {
         $cm = new ClassMetadata('stdClass');
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'one',
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_ID,
-        ));
+        ]);
     }
 
     /**
@@ -508,12 +519,12 @@ public function testAtomicCollectionUpdateUsageInEmbeddedDocument()
         $cm = new ClassMetadata(get_class($object));
         $cm->isEmbeddedDocument = true;
 
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'many',
             'reference' => true,
             'type' => 'many',
             'strategy' => ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET,
-        ));
+        ]);
     }
 
     public function testDefaultStorageStrategyOfEmbeddedDocumentFields()
@@ -525,10 +536,10 @@ public function testDefaultStorageStrategyOfEmbeddedDocumentFields()
         $cm = new ClassMetadata(get_class($object));
         $cm->isEmbeddedDocument = true;
 
-        $mapping = $cm->mapField(array(
+        $mapping = $cm->mapField([
             'fieldName' => 'many',
-            'type' => 'many'
-        ));
+            'type' => 'many',
+        ]);
 
         self::assertEquals(CollectionHelper::DEFAULT_STRATEGY, $mapping['strategy']);
     }
@@ -539,11 +550,11 @@ public function testDefaultStorageStrategyOfEmbeddedDocumentFields()
      */
     public function testOwningAndInversedRefsNeedTargetDocument($config)
     {
-        $config = array_merge($config, array(
+        $config = array_merge($config, [
             'fieldName' => 'many',
             'reference' => true,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_ATOMIC_SET,
-        ));
+        ]);
 
         $cm = new ClassMetadata('stdClass');
         $cm->isEmbeddedDocument = true;
@@ -552,30 +563,28 @@ public function testOwningAndInversedRefsNeedTargetDocument($config)
 
     public function provideOwningAndInversedRefsNeedTargetDocument()
     {
-        return array(
-            array(array('type' => 'one', 'mappedBy' => 'post')),
-            array(array('type' => 'one', 'inversedBy' => 'post')),
-            array(array('type' => 'many', 'mappedBy' => 'post')),
-            array(array('type' => 'many', 'inversedBy' => 'post')),
-        );
+        return [
+            [['type' => 'one', 'mappedBy' => 'post']],
+            [['type' => 'one', 'inversedBy' => 'post']],
+            [['type' => 'many', 'mappedBy' => 'post']],
+            [['type' => 'many', 'inversedBy' => 'post']],
+        ];
     }
 
     public function testAddInheritedAssociationMapping()
     {
         $cm = new ClassMetadata('stdClass');
 
-        $mapping = array(
+        $mapping = [
             'fieldName' => 'assoc',
             'reference' => true,
             'type' => 'one',
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_ID,
-        );
+        ];
 
         $cm->addInheritedAssociationMapping($mapping);
 
-        $expected = array(
-            'assoc' => $mapping,
-        );
+        $expected = ['assoc' => $mapping];
 
         $this->assertEquals($expected, $cm->associationMappings);
     }
@@ -588,10 +597,10 @@ public function testIdFieldsTypeMustNotBeOverridden()
     {
         $cm = new ClassMetadata('stdClass');
         $cm->setIdentifier('id');
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'id',
-            'type' => 'string'
-        ));
+            'type' => 'string',
+        ]);
     }
 
     /**
@@ -601,34 +610,34 @@ public function testIdFieldsTypeMustNotBeOverridden()
     public function testReferenceManySortMustNotBeUsedWithNonSetCollectionStrategy()
     {
         $cm = new ClassMetadata('stdClass');
-        $cm->mapField(array(
+        $cm->mapField([
             'fieldName' => 'ref',
             'reference' => true,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_PUSH_ALL,
             'type' => 'many',
-            'sort' => array('foo' => 1)
-        ));
+            'sort' => ['foo' => 1],
+        ]);
     }
 
     public function testSetShardKeyForClassWithoutInheritance()
     {
         $cm = new ClassMetadata('stdClass');
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
 
         $shardKey = $cm->getShardKey();
 
-        $this->assertEquals(array('id' => 1), $shardKey['keys']);
+        $this->assertEquals(['id' => 1], $shardKey['keys']);
     }
 
     public function testSetShardKeyForClassWithSingleCollectionInheritance()
     {
         $cm = new ClassMetadata('stdClass');
         $cm->inheritanceType = ClassMetadata::INHERITANCE_TYPE_SINGLE_COLLECTION;
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
 
         $shardKey = $cm->getShardKey();
 
-        $this->assertEquals(array('id' => 1), $shardKey['keys']);
+        $this->assertEquals(['id' => 1], $shardKey['keys']);
     }
 
     /**
@@ -638,21 +647,21 @@ public function testSetShardKeyForClassWithSingleCollectionInheritance()
     public function testSetShardKeyForClassWithSingleCollectionInheritanceWhichAlreadyHasIt()
     {
         $cm = new ClassMetadata('stdClass');
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
         $cm->inheritanceType = ClassMetadata::INHERITANCE_TYPE_SINGLE_COLLECTION;
 
-        $cm->setShardKey(array('foo' => 'asc'));
+        $cm->setShardKey(['foo' => 'asc']);
     }
 
     public function testSetShardKeyForClassWithCollPerClassInheritance()
     {
         $cm = new ClassMetadata('stdClass');
         $cm->inheritanceType = ClassMetadata::INHERITANCE_TYPE_COLLECTION_PER_CLASS;
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
 
         $shardKey = $cm->getShardKey();
 
-        $this->assertEquals(array('id' => 1), $shardKey['keys']);
+        $this->assertEquals(['id' => 1], $shardKey['keys']);
     }
 
     public function testIsNotShardedIfThereIsNoShardKey()
@@ -665,7 +674,7 @@ public function testIsNotShardedIfThereIsNoShardKey()
     public function testIsShardedIfThereIsAShardKey()
     {
         $cm = new ClassMetadata('stdClass');
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
 
         $this->assertTrue($cm->isSharded());
     }
@@ -678,7 +687,7 @@ public function testEmbeddedDocumentCantHaveShardKey()
     {
         $cm = new ClassMetadata('stdClass');
         $cm->isEmbeddedDocument = true;
-        $cm->setShardKey(array('id' => 'asc'));
+        $cm->setShardKey(['id' => 'asc']);
     }
 
     /**
@@ -697,7 +706,7 @@ public function testNoIncrementFieldsAllowedInShardKey()
             'type' => 'int',
             'strategy' => ClassMetadata::STORAGE_STRATEGY_INCREMENT,
         ]);
-        $cm->setShardKey(array('inc' => 1));
+        $cm->setShardKey(['inc' => 1]);
     }
 
     /**
@@ -713,9 +722,9 @@ public function testNoCollectionsInShardKey()
         $cm = new ClassMetadata(get_class($object));
         $cm->mapField([
             'fieldName' => 'collection',
-            'type' => 'collection'
+            'type' => 'collection',
         ]);
-        $cm->setShardKey(array('collection' => 1));
+        $cm->setShardKey(['collection' => 1]);
     }
 
     /**
@@ -730,7 +739,7 @@ public function testNoEmbedManyInShardKey()
 
         $cm = new ClassMetadata(get_class($object));
         $cm->mapManyEmbedded(['fieldName' => 'embedMany']);
-        $cm->setShardKey(array('embedMany' => 1));
+        $cm->setShardKey(['embedMany' => 1]);
     }
 
     /**
@@ -745,7 +754,7 @@ public function testNoReferenceManyInShardKey()
 
         $cm = new ClassMetadata(get_class($object));
         $cm->mapManyEmbedded(['fieldName' => 'referenceMany']);
-        $cm->setShardKey(array('referenceMany' => 1));
+        $cm->setShardKey(['referenceMany' => 1]);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Documents/GlobalNamespaceDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Documents/GlobalNamespaceDocument.php
index ecdb96eb07..bc636d1ece 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Documents/GlobalNamespaceDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Documents/GlobalNamespaceDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /**
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/AbstractDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/AbstractDriverTest.php
index 31aa7fe41c..23189d6d57 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/AbstractDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/AbstractDriverTest.php
@@ -1,10 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping\Driver;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
-use TestDocuments\PrimedCollectionDocument;
 use PHPUnit\Framework\TestCase;
+use TestDocuments\PrimedCollectionDocument;
 
 require_once 'fixtures/InvalidPartialFilterDocument.php';
 require_once 'fixtures/PartialFilterDocument.php';
@@ -24,16 +26,15 @@ public function setUp()
 
     public function tearDown()
     {
-        unset ($this->driver);
+        unset($this->driver);
     }
 
     public function testDriver()
     {
-
         $classMetadata = new ClassMetadata('TestDocuments\User');
         $this->driver->loadMetadataForClass('TestDocuments\User', $classMetadata);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'id',
             'id' => true,
             'name' => '_id',
@@ -45,10 +46,10 @@ public function testDriver()
             'isCascadeRemove' => false,
             'isInverseSide' => false,
             'isOwningSide' => true,
-            'nullable' => false
-        ), $classMetadata->fieldMappings['id']);
+            'nullable' => false,
+        ], $classMetadata->fieldMappings['id']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'username',
             'name' => 'username',
             'type' => 'string',
@@ -63,16 +64,16 @@ public function testDriver()
             'unique' => true,
             'sparse' => true,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['username']);
+        ], $classMetadata->fieldMappings['username']);
 
-        $this->assertEquals(array(
-            array(
-                'keys' => array('username' => 1),
-                'options' => array('unique' => true, 'sparse' => true)
-            )
-        ), $classMetadata->getIndexes());
+        $this->assertEquals([
+            [
+                'keys' => ['username' => 1],
+                'options' => ['unique' => true, 'sparse' => true],
+            ],
+        ], $classMetadata->getIndexes());
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'createdAt',
             'name' => 'createdAt',
             'type' => 'date',
@@ -85,9 +86,9 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['createdAt']);
+        ], $classMetadata->fieldMappings['createdAt']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'tags',
             'name' => 'tags',
             'type' => 'collection',
@@ -100,9 +101,9 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['tags']);
+        ], $classMetadata->fieldMappings['tags']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'association' => 3,
             'fieldName' => 'address',
             'name' => 'address',
@@ -119,9 +120,9 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['address']);
+        ], $classMetadata->fieldMappings['address']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'association' => 4,
             'fieldName' => 'phonenumbers',
             'name' => 'phonenumbers',
@@ -138,9 +139,9 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_PUSH_ALL,
-        ), $classMetadata->fieldMappings['phonenumbers']);
+        ], $classMetadata->fieldMappings['phonenumbers']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'association' => 1,
             'fieldName' => 'profile',
             'name' => 'profile',
@@ -149,7 +150,7 @@ public function testDriver()
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_ID,
             'targetDocument' => 'Documents\Profile',
             'collectionClass' => null,
-            'cascade' => array('remove', 'persist', 'refresh', 'merge', 'detach'),
+            'cascade' => ['remove', 'persist', 'refresh', 'merge', 'detach'],
             'isCascadeDetach' => true,
             'isCascadeMerge' => true,
             'isCascadePersist' => true,
@@ -166,9 +167,9 @@ public function testDriver()
             'skip' => null,
             'orphanRemoval' => true,
             'prime' => [],
-        ), $classMetadata->fieldMappings['profile']);
+        ], $classMetadata->fieldMappings['profile']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'association' => 1,
             'fieldName' => 'account',
             'name' => 'account',
@@ -177,7 +178,7 @@ public function testDriver()
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF,
             'targetDocument' => 'Documents\Account',
             'collectionClass' => null,
-            'cascade' => array('remove', 'persist', 'refresh', 'merge', 'detach'),
+            'cascade' => ['remove', 'persist', 'refresh', 'merge', 'detach'],
             'isCascadeDetach' => true,
             'isCascadeMerge' => true,
             'isCascadePersist' => true,
@@ -194,9 +195,9 @@ public function testDriver()
             'skip' => null,
             'orphanRemoval' => false,
             'prime' => [],
-        ), $classMetadata->fieldMappings['account']);
+        ], $classMetadata->fieldMappings['account']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'association' => 2,
             'fieldName' => 'groups',
             'name' => 'groups',
@@ -205,7 +206,7 @@ public function testDriver()
             'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF,
             'targetDocument' => 'Documents\Group',
             'collectionClass' => null,
-            'cascade' => array('remove', 'persist', 'refresh', 'merge', 'detach'),
+            'cascade' => ['remove', 'persist', 'refresh', 'merge', 'detach'],
             'isCascadeDetach' => true,
             'isCascadeMerge' => true,
             'isCascadePersist' => true,
@@ -222,27 +223,27 @@ public function testDriver()
             'skip' => null,
             'orphanRemoval' => false,
             'prime' => [],
-        ), $classMetadata->fieldMappings['groups']);
+        ], $classMetadata->fieldMappings['groups']);
 
         $this->assertEquals(
-            array(
-                'postPersist' => array('doStuffOnPostPersist', 'doOtherStuffOnPostPersist'),
-                'prePersist' => array('doStuffOnPrePersist'),
-            ),
+            [
+                'postPersist' => ['doStuffOnPostPersist', 'doOtherStuffOnPostPersist'],
+                'prePersist' => ['doStuffOnPrePersist'],
+            ],
             $classMetadata->lifecycleCallbacks
         );
 
         $this->assertEquals(
-            array(
-                "doStuffOnAlsoLoad" => array("unmappedField"),
-            ),
+            [
+                'doStuffOnAlsoLoad' => ['unmappedField'],
+            ],
             $classMetadata->alsoLoadMethods
         );
 
         $classMetadata = new ClassMetadata('TestDocuments\EmbeddedDocument');
         $this->driver->loadMetadataForClass('TestDocuments\EmbeddedDocument', $classMetadata);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'name',
             'name' => 'name',
             'type' => 'string',
@@ -255,12 +256,12 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['name']);
+        ], $classMetadata->fieldMappings['name']);
 
         $classMetadata = new ClassMetadata('TestDocuments\QueryResultDocument');
         $this->driver->loadMetadataForClass('TestDocuments\QueryResultDocument', $classMetadata);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'name',
             'name' => 'name',
             'type' => 'string',
@@ -273,9 +274,9 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['name']);
+        ], $classMetadata->fieldMappings['name']);
 
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'count',
             'name' => 'count',
             'type' => 'integer',
@@ -288,7 +289,7 @@ public function testDriver()
             'isOwningSide' => true,
             'nullable' => false,
             'strategy' => ClassMetadata::STORAGE_STRATEGY_SET,
-        ), $classMetadata->fieldMappings['count']);
+        ], $classMetadata->fieldMappings['count']);
     }
 
     public function testPartialFilterExpressions()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/XmlDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/XmlDriverTest.php
index fbcceb1a21..d3945fe205 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/XmlDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/XmlDriverTest.php
@@ -1,9 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping\Driver;
 
-use Doctrine\ODM\MongoDB\Mapping\Driver\XmlDriver;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+use Doctrine\ODM\MongoDB\Mapping\Driver\XmlDriver;
 
 class XmlDriverTest extends AbstractDriverTest
 {
@@ -16,13 +18,13 @@ public function testDriverShouldReturnOptionsForCustomIdGenerator()
     {
         $classMetadata = new ClassMetadata('TestDocuments\UserCustomIdGenerator');
         $this->driver->loadMetadataForClass('TestDocuments\UserCustomIdGenerator', $classMetadata);
-        $this->assertEquals(array(
+        $this->assertEquals([
             'fieldName' => 'id',
             'strategy' => 'custom',
-            'options' => array(
+            'options' => [
                 'class' => 'TestDocuments\CustomIdGenerator',
-                'someOption' => 'some-option'
-            ),
+                'someOption' => 'some-option',
+            ],
             'id' => true,
             'name' => '_id',
             'type' => 'custom_id',
@@ -33,8 +35,8 @@ public function testDriverShouldReturnOptionsForCustomIdGenerator()
             'isCascadeRemove' => false,
             'isInverseSide' => false,
             'isOwningSide' => true,
-            'nullable' => false
-        ), $classMetadata->fieldMappings['id']);
+            'nullable' => false,
+        ], $classMetadata->fieldMappings['id']);
     }
 
     public function testDriverShouldParseNonStringAttributes()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/EmbeddedDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/EmbeddedDocument.php
index 5c4934fef3..23985adb6b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/EmbeddedDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/EmbeddedDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
 class EmbeddedDocument
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/InvalidPartialFilterDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/InvalidPartialFilterDocument.php
index 99759a2e49..4bdac2bd8a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/InvalidPartialFilterDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/InvalidPartialFilterDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
 class InvalidPartialFilterDocument
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PartialFilterDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PartialFilterDocument.php
index a2fa2e0f42..176aab65c2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PartialFilterDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PartialFilterDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
 class PartialFilterDocument
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PrimedCollectionDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PrimedCollectionDocument.php
index f0fdade738..064fe408a6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PrimedCollectionDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/PrimedCollectionDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/QueryResultDocument.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/QueryResultDocument.php
index c3cd41bf83..1aeb5f08d7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/QueryResultDocument.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/QueryResultDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
 class QueryResultDocument
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/User.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/User.php
index cff238bcb1..eeefd561a3 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/User.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Driver/fixtures/User.php
@@ -1,7 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace TestDocuments;
 
+use Doctrine\Common\Collections\ArrayCollection;
+
 class User
 {
     protected $id;
@@ -22,14 +26,14 @@ class User
 
     protected $account;
 
-    protected $tags = array();
+    protected $tags = [];
 
     protected $test;
 
     public function __construct()
     {
-        $this->phonenumbers = new \Doctrine\Common\Collections\ArrayCollection();
-        $this->groups = array();
+        $this->phonenumbers = new ArrayCollection();
+        $this->groups = [];
         $this->createdAt = new \DateTime();
     }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ShardKeyInheritanceMappingTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ShardKeyInheritanceMappingTest.php
index 7476829970..df8d8f7696 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ShardKeyInheritanceMappingTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/ShardKeyInheritanceMappingTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -25,7 +27,7 @@ public function testShardKeyFromMappedSuperclass()
         $class = $this->factory->getMetadataFor(ShardedSubclass::class);
 
         $this->assertTrue($class->isSharded());
-        $this->assertEquals(array('keys' => array('_id' => 1), 'options' => array()), $class->getShardKey());
+        $this->assertEquals(['keys' => ['_id' => 1], 'options' => []], $class->getShardKey());
     }
 
     public function testShardKeySingleCollectionInheritance()
@@ -33,7 +35,7 @@ public function testShardKeySingleCollectionInheritance()
         $class = $this->factory->getMetadataFor(ShardedSingleCollInheritance2::class);
 
         $this->assertTrue($class->isSharded());
-        $this->assertEquals(array('keys' => array('_id' => 1), 'options' => array()), $class->getShardKey());
+        $this->assertEquals(['keys' => ['_id' => 1], 'options' => []], $class->getShardKey());
     }
 
     /**
@@ -49,7 +51,7 @@ public function testShardKeyCollectionPerClassInheritance()
         $class = $this->factory->getMetadataFor(ShardedCollectionPerClass2::class);
 
         $this->assertTrue($class->isSharded());
-        $this->assertEquals(array('keys' => array('_id' => 1), 'options' => array()), $class->getShardKey());
+        $this->assertEquals(['keys' => ['_id' => 1], 'options' => []], $class->getShardKey());
     }
 
     public function testShardKeyCollectionPerClassInheritanceOverriding()
@@ -57,7 +59,7 @@ public function testShardKeyCollectionPerClassInheritanceOverriding()
         $class = $this->factory->getMetadataFor(ShardedCollectionPerClass3::class);
 
         $this->assertTrue($class->isSharded());
-        $this->assertEquals(array('keys' => array('_id' => 'hashed'), 'options' => array()), $class->getShardKey());
+        $this->assertEquals(['keys' => ['_id' => 'hashed'], 'options' => []], $class->getShardKey());
     }
 }
 
@@ -94,14 +96,16 @@ class ShardedSingleCollInheritance1
  * @ODM\Document
  */
 class ShardedSingleCollInheritance2 extends ShardedSingleCollInheritance1
-{}
+{
+}
 
 /**
  * @ODM\Document
  * @ODM\ShardKey(keys={"_id"="hashed"})
  */
 class ShardedSingleCollInheritance3 extends ShardedSingleCollInheritance1
-{}
+{
+}
 
 /**
  * @ODM\Document
@@ -118,11 +122,13 @@ class ShardedCollectionPerClass1
  * @ODM\Document
  */
 class ShardedCollectionPerClass2 extends ShardedCollectionPerClass1
-{}
+{
+}
 
 /**
  * @ODM\Document
  * @ODM\ShardKey(keys={"_id"="hashed"})
  */
 class ShardedCollectionPerClass3 extends ShardedCollectionPerClass1
-{}
+{
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/AbstractDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/AbstractDriverTest.php
index b028eab87d..a1c4a5b4f4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/AbstractDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/AbstractDriverTest.php
@@ -1,8 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping\Symfony;
 
+use Doctrine\Common\Persistence\Mapping\MappingException;
 use PHPUnit\Framework\TestCase;
+use function mkdir;
+use function rmdir;
+use function sys_get_temp_dir;
+use function touch;
+use function unlink;
 
 /**
  * @group DDC-1418
@@ -11,52 +19,52 @@ abstract class AbstractDriverTest extends TestCase
 {
     public function testFindMappingFile()
     {
-        $driver = $this->getDriver(array(
+        $driver = $this->getDriver([
             'MyNamespace\MySubnamespace\DocumentFoo' => 'foo',
             'MyNamespace\MySubnamespace\Document' => $this->dir,
-        ));
+        ]);
 
-        touch($filename = $this->dir.'/Foo'.$this->getFileExtension());
+        touch($filename = $this->dir . '/Foo' . $this->getFileExtension());
         $this->assertEquals($filename, $driver->getLocator()->findMappingFile('MyNamespace\MySubnamespace\Document\Foo'));
     }
 
     public function testFindMappingFileInSubnamespace()
     {
-        $driver = $this->getDriver(array(
+        $driver = $this->getDriver([
             'MyNamespace\MySubnamespace\Document' => $this->dir,
-        ));
+        ]);
 
-        touch($filename = $this->dir.'/Foo.Bar'.$this->getFileExtension());
+        touch($filename = $this->dir . '/Foo.Bar' . $this->getFileExtension());
         $this->assertEquals($filename, $driver->getLocator()->findMappingFile('MyNamespace\MySubnamespace\Document\Foo\Bar'));
     }
 
     public function testFindMappingFileNamespacedFoundFileNotFound()
     {
-        $this->expectException(\Doctrine\Common\Persistence\Mapping\MappingException::class);
-        $this->expectExceptionMessage("No mapping file found named");
+        $this->expectException(MappingException::class);
+        $this->expectExceptionMessage('No mapping file found named');
 
-        $driver = $this->getDriver(array(
+        $driver = $this->getDriver([
             'MyNamespace\MySubnamespace\Document' => $this->dir,
-        ));
+        ]);
 
         $driver->getLocator()->findMappingFile('MyNamespace\MySubnamespace\Document\Foo');
     }
 
     public function testFindMappingNamespaceNotFound()
     {
-        $this->expectException(\Doctrine\Common\Persistence\Mapping\MappingException::class);
-        $this->expectExceptionMessage("No mapping file found named 'Foo".$this->getFileExtension()."' for class 'MyOtherNamespace\MySubnamespace\Document\Foo'.");
+        $this->expectException(MappingException::class);
+        $this->expectExceptionMessage("No mapping file found named 'Foo" . $this->getFileExtension() . "' for class 'MyOtherNamespace\MySubnamespace\Document\Foo'.");
 
-        $driver = $this->getDriver(array(
+        $driver = $this->getDriver([
             'MyNamespace\MySubnamespace\Document' => $this->dir,
-        ));
+        ]);
 
         $driver->getLocator()->findMappingFile('MyOtherNamespace\MySubnamespace\Document\Foo');
     }
 
     protected function setUp()
     {
-        $this->dir = sys_get_temp_dir().'/abstract_driver_test';
+        $this->dir = sys_get_temp_dir() . '/abstract_driver_test';
         @mkdir($this->dir, 0775, true);
     }
 
@@ -66,9 +74,9 @@ protected function tearDown()
 
         foreach ($iterator as $path) {
             if ($path->isDir()) {
-                @rmdir($path);
+                @rmdir((string) $path);
             } else {
-                @unlink($path);
+                @unlink((string) $path);
             }
         }
 
@@ -76,7 +84,7 @@ protected function tearDown()
     }
 
     abstract protected function getFileExtension();
-    abstract protected function getDriver(array $paths = array());
+    abstract protected function getDriver(array $paths = []);
 
     private function setField($obj, $field, $value)
     {
@@ -85,7 +93,7 @@ private function setField($obj, $field, $value)
         $ref->setValue($obj, $value);
     }
 
-    private function invoke($obj, $method, array $args = array())
+    private function invoke($obj, $method, array $args = [])
     {
         $ref = new \ReflectionMethod($obj, $method);
         $ref->setAccessible(true);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/XmlDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/XmlDriverTest.php
index dd0fd0c3b2..6b1d04b9bf 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/XmlDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/Symfony/XmlDriverTest.php
@@ -1,8 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping\Symfony;
 
 use Doctrine\ODM\MongoDB\Mapping\Driver\SimplifiedXmlDriver;
+use function array_flip;
 
 /**
  * @group DDC-1418
@@ -14,7 +17,7 @@ protected function getFileExtension()
         return '.mongodb-odm.xml';
     }
 
-    protected function getDriver(array $paths = array())
+    protected function getDriver(array $paths = [])
     {
         $driver = new SimplifiedXmlDriver(array_flip($paths));
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
index 0cbfdec6f6..31d997d32e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mapping;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Mapping\Driver\XmlDriver;
 use Documents\User;
+use const DIRECTORY_SEPARATOR;
+use function get_class;
 
 class XmlMappingDriverTest extends AbstractMappingDriverTest
 {
@@ -26,8 +30,8 @@ public function testSetShardKeyOptionsByAttributes()
 
         $this->assertTrue($class->isSharded());
         $shardKey = $class->getShardKey();
-        $this->assertSame(array('unique' => true, 'numInitialChunks' => 4096), $shardKey['options']);
-        $this->assertSame(array('_id' => 1), $shardKey['keys']);
+        $this->assertSame(['unique' => true, 'numInitialChunks' => 4096], $shardKey['options']);
+        $this->assertSame(['_id' => 1], $shardKey['keys']);
     }
 
     public function testGetAssociationCollectionClass()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ClassMetadataMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ClassMetadataMock.php
index 0232758414..609da45e9e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ClassMetadataMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ClassMetadataMock.php
@@ -1,7 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
-class ClassMetadataMock extends \Doctrine\ODM\MongoDB\Mapping\ClassMetadata
+use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
+
+class ClassMetadataMock extends ClassMetadata
 {
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentManagerMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentManagerMock.php
index 8dafd72644..ac87fb60e6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentManagerMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentManagerMock.php
@@ -1,8 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
+use function get_parent_class;
 
 class DocumentManagerMock extends DocumentManager
 {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentPersisterMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentPersisterMock.php
index 7ba8978c06..3e71be360c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentPersisterMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/DocumentPersisterMock.php
@@ -1,26 +1,30 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
+use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
+
 /**
  * DocumentPersister implementation used for mocking during tests.
  */
-class DocumentPersisterMock extends \Doctrine\ODM\MongoDB\Persisters\DocumentPersister
+class DocumentPersisterMock extends DocumentPersister
 {
-    private $inserts = array();
-    private $upserts = array();
-    private $updates = array();
-    private $deletes = array();
+    private $inserts = [];
+    private $upserts = [];
+    private $updates = [];
+    private $deletes = [];
     private $identityColumnValueCounter = 1;
     private $mockIdGeneratorType;
-    private $postInsertIds = array();
+    private $postInsertIds = [];
     private $existsCalled = false;
 
-    public function insert($document, array $options = array())
+    public function insert($document, array $options = [])
     {
         $this->inserts[] = $document;
         $id = $this->identityColumnValueCounter++;
-        $this->postInsertIds[$id] = array($id, $document);
+        $this->postInsertIds[$id] = [$id, $document];
         return $id;
     }
 
@@ -28,7 +32,7 @@ public function addInsert($document)
     {
         $this->inserts[] = $document;
         $id = $this->identityColumnValueCounter++;
-        $this->postInsertIds[$id] = array($id, $document);
+        $this->postInsertIds[$id] = [$id, $document];
         return $id;
     }
 
@@ -36,19 +40,19 @@ public function addUpsert($document)
     {
         $this->upserts[] = $document;
         $id = $this->identityColumnValueCounter++;
-        $this->postInsertIds[$id] = array($id, $document);
+        $this->postInsertIds[$id] = [$id, $document];
         return $id;
     }
 
-    public function executeInserts(array $options = array())
+    public function executeInserts(array $options = [])
     {
     }
 
-    public function executeUpserts(array $options = array())
+    public function executeUpserts(array $options = [])
     {
     }
 
-    public function update($document, array $options = array())
+    public function update($document, array $options = [])
     {
         $this->updates[] = $document;
     }
@@ -58,7 +62,7 @@ public function exists($document)
         $this->existsCalled = true;
     }
 
-    public function delete($document, array $options = array())
+    public function delete($document, array $options = [])
     {
         $this->deletes[] = $document;
     }
@@ -87,9 +91,9 @@ public function reset()
     {
         $this->existsCalled = false;
         $this->identityColumnValueCounter = 1;
-        $this->inserts = array();
-        $this->updates = array();
-        $this->deletes = array();
+        $this->inserts = [];
+        $this->updates = [];
+        $this->deletes = [];
     }
 
     public function isExistsCalled()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ExceptionThrowingListenerMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ExceptionThrowingListenerMock.php
index 7a3f8724c5..4f3a72a29f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ExceptionThrowingListenerMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/ExceptionThrowingListenerMock.php
@@ -1,18 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
-use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
-use Doctrine\ODM\MongoDB\Event\PreUpdateEventArgs;
 use Doctrine\Common\EventSubscriber;
+use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 
 class ExceptionThrowingListenerMock implements EventSubscriber
 {
     public function getSubscribedEvents()
     {
-        return [
-            'onFlush',
-        ];
+        return ['onFlush'];
     }
 
     public function onFlush(OnFlushEventArgs $args)
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/MetadataDriverMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/MetadataDriverMock.php
index 3d918e1770..3a721b924f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/MetadataDriverMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/MetadataDriverMock.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
 use Doctrine\Common\Persistence\Mapping\ClassMetadata;
@@ -19,6 +21,6 @@ public function isTransient($className)
 
     public function getAllClassNames()
     {
-        return array();
+        return [];
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/PreUpdateListenerMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/PreUpdateListenerMock.php
index 465e8323cd..ec92e0c2b2 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/PreUpdateListenerMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/PreUpdateListenerMock.php
@@ -1,19 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
+use Doctrine\Common\EventSubscriber;
 use Doctrine\ODM\MongoDB\Event\OnFlushEventArgs;
 use Doctrine\ODM\MongoDB\Event\PreUpdateEventArgs;
-use Doctrine\Common\EventSubscriber;
+use function spl_object_hash;
 
 class PreUpdateListenerMock implements EventSubscriber
 {
     public function getSubscribedEvents()
     {
-        return array(
+        return [
             'onFlush',
-            'preUpdate'
-        );
+            'preUpdate',
+        ];
     }
 
     public function onFlush(OnFlushEventArgs $args)
@@ -26,6 +29,6 @@ public function onFlush(OnFlushEventArgs $args)
 
     public function preUpdate(PreUpdateEventArgs $args)
     {
-        return; // fatal error
+        return;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/UnitOfWorkMock.php b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/UnitOfWorkMock.php
index 0c76946ebc..c020bd10f5 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mocks/UnitOfWorkMock.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mocks/UnitOfWorkMock.php
@@ -1,15 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Mocks;
 
-class UnitOfWorkMock extends \Doctrine\ODM\MongoDB\UnitOfWork
+use Doctrine\ODM\MongoDB\UnitOfWork;
+use function spl_object_hash;
+
+class UnitOfWorkMock extends UnitOfWork
 {
-    private $_mockDataChangeSets = array();
+    private $_mockDataChangeSets = [];
     private $_persisterMock;
 
-    /**
-     * @override
-     */
     public function getDocumentPersister($documentName)
     {
         return $this->_persisterMock[$documentName] ?? parent::getDocumentPersister($documentName);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/MongoCollectionTest.php b/tests/Doctrine/ODM/MongoDB/Tests/MongoCollectionTest.php
index a4906d8d9b..d406668a59 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/MongoCollectionTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/MongoCollectionTest.php
@@ -1,12 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
-class MongoCollectionTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MongoCollectionTest extends BaseTest
 {
     public function testGridFSEmptyResult()
     {
         $mongoCollection = $this->dm->getDocumentCollection('Documents\File');
-        $this->assertNull($mongoCollection->findOne(array('_id' => 'definitelynotanid')));
+        $this->assertNull($mongoCollection->findOne(['_id' => 'definitelynotanid']));
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Performance/HydrationPerformanceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Performance/HydrationPerformanceTest.php
index e050339140..9b44957018 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Performance/HydrationPerformanceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Performance/HydrationPerformanceTest.php
@@ -1,13 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\Tests\ODM\MongoDB\Performance;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsUser;
+use const PHP_EOL;
+use function gc_collect_cycles;
+use function memory_get_usage;
+use function microtime;
 
 /**
  * @group performance
  */
-class HydrationPerformanceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class HydrationPerformanceTest extends BaseTest
 {
     /**
      * [jwage: 10000 objects in ~6 seconds]
@@ -18,12 +25,12 @@ public function testHydrationPerformance()
 
         $batchSize = 20;
         for ($i = 1; $i <= 10000; ++$i) {
-            $user = new CmsUser;
+            $user = new CmsUser();
             $user->status = 'user';
             $user->username = 'user' . $i;
             $user->name = 'Mr.Smith-' . $i;
             $this->dm->persist($user);
-            if (($i % $batchSize) == 0) {
+            if (($i % $batchSize) === 0) {
                 $this->dm->flush();
                 $this->dm->clear();
             }
@@ -31,16 +38,14 @@ public function testHydrationPerformance()
 
         gc_collect_cycles();
 
-        echo "Memory usage before: " . (memory_get_usage() / 1024) . " KB" . PHP_EOL;
+        echo 'Memory usage before: ' . (memory_get_usage() / 1024) . ' KB' . PHP_EOL;
 
-        $users = $this->dm->getRepository('Documents\CmsUser')->findAll();
-        foreach ($users as $user) {
-        }
+        $this->dm->getRepository('Documents\CmsUser')->findAll();
 
         $this->dm->clear();
         gc_collect_cycles();
 
-        echo "Memory usage after: " . (memory_get_usage() / 1024) . " KB" . PHP_EOL;
+        echo 'Memory usage after: ' . (memory_get_usage() / 1024) . ' KB' . PHP_EOL;
 
         $e = microtime(true);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Performance/InsertPerformanceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Performance/InsertPerformanceTest.php
index c559fe9d76..9f72a97834 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Performance/InsertPerformanceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Performance/InsertPerformanceTest.php
@@ -1,13 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\Tests\ODM\MongoDB\Performance;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsUser;
+use const PHP_EOL;
+use function gc_collect_cycles;
+use function memory_get_usage;
+use function microtime;
 
 /**
  * @group performance
  */
-class InsertPerformanceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class InsertPerformanceTest extends BaseTest
 {
     /**
      * [jwage: 10000 objects in ~4 seconds]
@@ -16,23 +23,23 @@ public function testInsertPerformance()
     {
         $s = microtime(true);
 
-        echo "Memory usage before: " . (memory_get_usage() / 1024) . " KB" . PHP_EOL;
+        echo 'Memory usage before: ' . (memory_get_usage() / 1024) . ' KB' . PHP_EOL;
 
         $batchSize = 20;
         for ($i = 1; $i <= 10000; ++$i) {
-            $user = new CmsUser;
+            $user = new CmsUser();
             $user->status = 'user';
             $user->username = 'user' . $i;
             $user->name = 'Mr.Smith-' . $i;
             $this->dm->persist($user);
-            if (($i % $batchSize) == 0) {
+            if (($i % $batchSize) === 0) {
                 $this->dm->flush();
                 $this->dm->clear();
             }
         }
 
         gc_collect_cycles();
-        echo "Memory usage after: " . (memory_get_usage() / 1024) . " KB" . PHP_EOL;
+        echo 'Memory usage after: ' . (memory_get_usage() / 1024) . ' KB' . PHP_EOL;
 
         $e = microtime(true);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Performance/MemoryUsageTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Performance/MemoryUsageTest.php
index 3b782e622b..dcdddc8f4a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Performance/MemoryUsageTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Performance/MemoryUsageTest.php
@@ -1,21 +1,34 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Performance;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsPhonenumber;
 use Documents\CmsUser;
+use const PHP_EOL;
+use function current;
+use function end;
+use function floor;
+use function gc_collect_cycles;
+use function log;
+use function memory_get_usage;
+use function pow;
+use function round;
+use function sprintf;
 
 /**
  * @group performance
  */
-class MemoryUsageTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class MemoryUsageTest extends BaseTest
 {
     /**
      * [jwage: Memory increased by 14.09 kb]
      */
     public function testMemoryUsage()
     {
-        $memoryUsage = array();
+        $memoryUsage = [];
         for ($i = 0; $i < 100; $i++) {
             $ph1 = new CmsPhonenumber();
             $ph1->phonenumber = '12345';
@@ -46,7 +59,7 @@ public function testMemoryUsage()
 
     private function formatMemory($size)
     {
-        $unit = array('b', 'kb', 'mb', 'gb', 'tb', 'pb');
+        $unit = ['b', 'kb', 'mb', 'gb', 'tb', 'pb'];
         return round($size / pow(1024, ($i = floor(log($size, 1024)))), 2) . ' ' . $unit[$i];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Performance/UnitOfWorkPerformanceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Performance/UnitOfWorkPerformanceTest.php
index 2884dd777c..fe28370e05 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Performance/UnitOfWorkPerformanceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Performance/UnitOfWorkPerformanceTest.php
@@ -1,22 +1,28 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\Tests\ODM\MongoDB\Performance;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\CmsUser;
+use const PHP_EOL;
+use function microtime;
+use function str_replace;
 
 /**
  * @group performance
  */
-class UnitOfWorkPerformanceTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class UnitOfWorkPerformanceTest extends BaseTest
 {
     /**
      * [jwage: compute changesets for 10000 objects in ~10 seconds]
      */
     public function testComputeChanges()
     {
-        $users = array();
+        $users = [];
         for ($i = 1; $i <= 10000; ++$i) {
-            $user = new CmsUser;
+            $user = new CmsUser();
             $user->status = 'user';
             $user->username = 'user' . $i;
             $user->name = 'Mr.Smith-' . $i;
@@ -35,6 +41,6 @@ public function testComputeChanges()
         $this->dm->flush();
         $e = microtime(true);
 
-        echo 'Compute ChangeSet '.$n.' objects in ' . ($e - $s) . ' seconds' . PHP_EOL;
+        echo 'Compute ChangeSet ' . $n . ' objects in ' . ($e - $s) . ' seconds' . PHP_EOL;
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollNoReturnType.php b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollNoReturnType.php
index e622f60a2e..f74ec815b1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollNoReturnType.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollNoReturnType.php
@@ -1,10 +1,11 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
-
-use Doctrine\Common\Collections\ArrayCollection;
-
-class CollNoReturnType extends ArrayCollection
-{
-
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
+
+use Doctrine\Common\Collections\ArrayCollection;
+
+class CollNoReturnType extends ArrayCollection
+{
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithNullableReturnType.php b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithNullableReturnType.php
index 28c9859262..9207dbbed4 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithNullableReturnType.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithNullableReturnType.php
@@ -1,13 +1,16 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
-
-use Doctrine\Common\Collections\ArrayCollection;
-
-class CollWithNullableReturnType extends ArrayCollection
-{
-    public function maybeGetDate(): ?\DateTime
-    {
-        return rand(0, 1) ? new \DateTime() : null;
-    }
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
+
+use Doctrine\Common\Collections\ArrayCollection;
+use function rand;
+
+class CollWithNullableReturnType extends ArrayCollection
+{
+    public function maybeGetDate(): ?\DateTime
+    {
+        return rand(0, 1) ? new \DateTime() : null;
+    }
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithReturnType.php b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithReturnType.php
index 9fa8b9c001..4aa8beeb68 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithReturnType.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/CollWithReturnType.php
@@ -1,13 +1,15 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
-
-use Doctrine\Common\Collections\ArrayCollection;
-
-class CollWithReturnType extends ArrayCollection
-{
-    public function getDate(): \DateTime
-    {
-        return new \DateTime();
-    }
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
+
+use Doctrine\Common\Collections\ArrayCollection;
+
+class CollWithReturnType extends ArrayCollection
+{
+    public function getDate(): \DateTime
+    {
+        return new \DateTime();
+    }
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/DefaultPersistentCollectionGeneratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/DefaultPersistentCollectionGeneratorTest.php
index 1141bd00a6..0f4ca1c4d3 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/DefaultPersistentCollectionGeneratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/DefaultPersistentCollectionGeneratorTest.php
@@ -1,52 +1,56 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
-
-use Doctrine\ODM\MongoDB\Configuration;
-use Doctrine\ODM\MongoDB\PersistentCollection\DefaultPersistentCollectionGenerator;
-use Doctrine\ODM\MongoDB\Tests\BaseTest;
-
-/**
- * Tests aims to check if classes generated for various PHP versions are correct (i.e. parses).
- */
-class DefaultPersistentCollectionGeneratorTest extends BaseTest
-{
-    /**
-     * @var DefaultPersistentCollectionGenerator
-     */
-    private $generator;
-
-    public function setUp()
-    {
-        parent::setUp();
-        $this->generator = new DefaultPersistentCollectionGenerator(
-            $this->dm->getConfiguration()->getPersistentCollectionDir(),
-            $this->dm->getConfiguration()->getPersistentCollectionNamespace()
-        );
-    }
-
-    public function testNoReturnTypes()
-    {
-        $class = $this->generator->loadClass(CollNoReturnType::class, Configuration::AUTOGENERATE_EVAL);
-        $coll = new $class(new CollNoReturnType(), $this->dm, $this->uow);
-        $this->assertInstanceOf(CollNoReturnType::class, $coll);
-    }
-
-    public function testWithReturnType()
-    {
-        $class = $this->generator->loadClass(CollWithReturnType::class, Configuration::AUTOGENERATE_EVAL);
-        $coll = new $class(new CollWithReturnType(), $this->dm, $this->uow);
-        $this->assertInstanceOf(CollWithReturnType::class, $coll);
-    }
-
-    public function testWithNullableReturnType()
-    {
-        if (PHP_VERSION_ID < 70100) {
-            $this->markTestSkipped(sprintf('%s requires at least PHP 7.1', __METHOD__));
-        }
-
-        $class = $this->generator->loadClass(CollWithNullableReturnType::class, Configuration::AUTOGENERATE_EVAL);
-        $coll = new $class(new CollWithNullableReturnType(), $this->dm, $this->uow);
-        $this->assertInstanceOf(CollWithNullableReturnType::class, $coll);
-    }
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\PersistentCollection;
+
+use Doctrine\ODM\MongoDB\Configuration;
+use Doctrine\ODM\MongoDB\PersistentCollection\DefaultPersistentCollectionGenerator;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use const PHP_VERSION_ID;
+use function sprintf;
+
+/**
+ * Tests aims to check if classes generated for various PHP versions are correct (i.e. parses).
+ */
+class DefaultPersistentCollectionGeneratorTest extends BaseTest
+{
+    /**
+     * @var DefaultPersistentCollectionGenerator
+     */
+    private $generator;
+
+    public function setUp()
+    {
+        parent::setUp();
+        $this->generator = new DefaultPersistentCollectionGenerator(
+            $this->dm->getConfiguration()->getPersistentCollectionDir(),
+            $this->dm->getConfiguration()->getPersistentCollectionNamespace()
+        );
+    }
+
+    public function testNoReturnTypes()
+    {
+        $class = $this->generator->loadClass(CollNoReturnType::class, Configuration::AUTOGENERATE_EVAL);
+        $coll = new $class(new CollNoReturnType(), $this->dm, $this->uow);
+        $this->assertInstanceOf(CollNoReturnType::class, $coll);
+    }
+
+    public function testWithReturnType()
+    {
+        $class = $this->generator->loadClass(CollWithReturnType::class, Configuration::AUTOGENERATE_EVAL);
+        $coll = new $class(new CollWithReturnType(), $this->dm, $this->uow);
+        $this->assertInstanceOf(CollWithReturnType::class, $coll);
+    }
+
+    public function testWithNullableReturnType()
+    {
+        if (PHP_VERSION_ID < 70100) {
+            $this->markTestSkipped(sprintf('%s requires at least PHP 7.1', __METHOD__));
+        }
+
+        $class = $this->generator->loadClass(CollWithNullableReturnType::class, Configuration::AUTOGENERATE_EVAL);
+        $coll = new $class(new CollWithNullableReturnType(), $this->dm, $this->uow);
+        $this->assertInstanceOf(CollWithNullableReturnType::class, $coll);
+    }
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollectionTest.php b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollectionTest.php
index 04ffb55374..7f6c0d510d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollectionTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollectionTest.php
@@ -1,16 +1,24 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
+use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\PersistentCollection;
+use Doctrine\ODM\MongoDB\UnitOfWork;
+use Documents\User;
+use function serialize;
+use function unserialize;
 
 class PersistentCollectionTest extends BaseTest
 {
     public function testSlice()
     {
-        list ($start, $limit) = array(0, 25);
+        list ($start, $limit) = [0, 25];
         $collection = $this->getMockCollection();
         $collection->expects($this->once())
             ->method('slice')
@@ -35,7 +43,7 @@ public function testExceptionForGetTypeClassWithoutDocumentManager()
         /** @var PersistentCollection $unserialized */
         $unserialized = unserialize($serialized);
 
-        $unserialized->setOwner($owner, array('targetDocument' => '\stdClass'));
+        $unserialized->setOwner($owner, ['targetDocument' => '\stdClass']);
         $unserialized->getTypeClass();
     }
 
@@ -63,7 +71,7 @@ public function testGetTypeClassWorksAfterUnserialization()
         /** @var PersistentCollection $unserialized */
         $unserialized = unserialize($serialized);
 
-        $unserialized->setOwner(new \Documents\User(), $this->dm->getClassMetadata('Documents\\User')->getFieldMapping('phonebooks'));
+        $unserialized->setOwner(new User(), $this->dm->getClassMetadata('Documents\\User')->getFieldMapping('phonebooks'));
         $unserialized->setDocumentManager($this->dm);
         $this->assertInstanceOf(ClassMetadata::class, $unserialized->getTypeClass());
     }
@@ -71,7 +79,6 @@ public function testGetTypeClassWorksAfterUnserialization()
     /**
      * @param array $expected
      * @param array $snapshot
-     * @param \Closure $callback
      *
      * @dataProvider dataGetDeletedDocuments
      */
@@ -93,44 +100,58 @@ public static function dataGetDeletedDocuments()
         $one = new \stdClass();
         $two = new \stdClass();
 
-        return array(
-            'sameItems' => array(
-                array(),
-                array($one),
-                function ($collection) {}
-            ),
-            'added' => array(
-                array(),
-                array($one),
-                function ($collection) use ($two) { $collection->add($two); }
-            ),
-            'removed' => array(
-                array($one),
-                array($one, $two),
-                function ($collection) use ($one) { $collection->removeElement($one); }
-            ),
-            'replaced' => array(
-                array($one),
-                array($one),
-                function ($collection) use ($one, $two) { $collection->removeElement($one); $collection->add($two); }
-            ),
-            'removed2' => array(
-                array($two),
-                array($one, $two),
-                function ($collection) use ($two) { $collection->removeElement($two); }
-            ),
-            'orderChanged' => array(
-                array(),
-                array($one, $two),
-                function ($collection) use ($one, $two) { $collection->removeElement($one); $collection->removeElement($two); $collection->add($two); $collection->add($one); }
-            ),
-        );
+        return [
+            'sameItems' => [
+                [],
+                [$one],
+                function ($collection) {
+                },
+            ],
+            'added' => [
+                [],
+                [$one],
+                function ($collection) use ($two) {
+                    $collection->add($two);
+                },
+            ],
+            'removed' => [
+                [$one],
+                [$one, $two],
+                function ($collection) use ($one) {
+                    $collection->removeElement($one);
+                },
+            ],
+            'replaced' => [
+                [$one],
+                [$one],
+                function ($collection) use ($one, $two) {
+                    $collection->removeElement($one);
+                    $collection->add($two);
+                },
+            ],
+            'removed2' => [
+                [$two],
+                [$one, $two],
+                function ($collection) use ($two) {
+                    $collection->removeElement($two);
+                },
+            ],
+            'orderChanged' => [
+                [],
+                [$one, $two],
+                function ($collection) use ($one, $two) {
+                    $collection->removeElement($one);
+                    $collection->removeElement($two);
+                    $collection->add($two);
+                    $collection->add($one);
+                },
+            ],
+        ];
     }
 
     /**
      * @param array $expected
      * @param array $snapshot
-     * @param \Closure $callback
      *
      * @dataProvider dataGetInsertedDocuments
      */
@@ -152,28 +173,39 @@ public static function dataGetInsertedDocuments()
         $one = new \stdClass();
         $two = new \stdClass();
 
-        return array(
-            'sameItems' => array(
-                array(),
-                array($one),
-                function ($collection) {}
-            ),
-            'added' => array(
-                array($two),
-                array($one),
-                function ($collection) use ($two) { $collection->add($two); }
-            ),
-            'replaced' => array(
-                array($two),
-                array($one),
-                function ($collection) use ($one, $two) { $collection->removeElement($one); $collection->add($two); }
-            ),
-            'orderChanged' => array(
-                array(),
-                array($one, $two),
-                function ($collection) use ($one, $two) { $collection->removeElement($one); $collection->removeElement($two); $collection->add($two); $collection->add($one); }
-            ),
-        );
+        return [
+            'sameItems' => [
+                [],
+                [$one],
+                function ($collection) {
+                },
+            ],
+            'added' => [
+                [$two],
+                [$one],
+                function ($collection) use ($two) {
+                    $collection->add($two);
+                },
+            ],
+            'replaced' => [
+                [$two],
+                [$one],
+                function ($collection) use ($one, $two) {
+                    $collection->removeElement($one);
+                    $collection->add($two);
+                },
+            ],
+            'orderChanged' => [
+                [],
+                [$one, $two],
+                function ($collection) use ($one, $two) {
+                    $collection->removeElement($one);
+                    $collection->removeElement($two);
+                    $collection->add($two);
+                    $collection->add($one);
+                },
+            ],
+        ];
     }
 
     public function testOffsetExistsIsForwarded()
@@ -243,7 +275,7 @@ public function testIsEmptyUsesCountWhenCollectionIsNotInitialized()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\DocumentManager
+     * @return DocumentManager
      */
     private function getMockDocumentManager()
     {
@@ -251,7 +283,7 @@ private function getMockDocumentManager()
     }
 
     /**
-     * @return \Doctrine\ODM\MongoDB\UnitOfWork
+     * @return UnitOfWork
      */
     private function getMockUnitOfWork()
     {
@@ -259,7 +291,7 @@ private function getMockUnitOfWork()
     }
 
     /**
-     * @return \Doctrine\Common\Collections\Collection
+     * @return Collection
      */
     private function getMockCollection()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterFilterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterFilterTest.php
index af674bc945..ef92e6d797 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterFilterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterFilterTest.php
@@ -1,8 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Persisters;
 
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\BlogPost;
+use Documents\Comment;
 
 class DocumentPersisterFilterTest extends BaseTest
 {
@@ -17,21 +21,23 @@ public function testAddFilterToPreparedQuery()
         $testFilter->setParameter('field', 'username');
         $testFilter->setParameter('value', 'Tim');
 
-        $preparedQuery = array('username' => 'Toby');
+        $preparedQuery = ['username' => 'Toby'];
 
-        $expectedCriteria = array('$and' => array(
-            array('username' => 'Toby'),
-            array('username' => 'Tim'),
-        ));
+        $expectedCriteria = [
+        '$and' => [
+            ['username' => 'Toby'],
+            ['username' => 'Tim'],
+        ],
+        ];
 
         $this->assertSame($expectedCriteria, $persister->addFilterToPreparedQuery($preparedQuery));
     }
 
     public function testFilterCrieriaShouldAndWithMappingCriteriaOwningSide()
     {
-        $blogPost = new \Documents\BlogPost('Roger');
-        $blogPost->addComment(new \Documents\Comment('comment by normal user', new \DateTime(), false));
-        $blogPost->addComment(new \Documents\Comment('comment by admin', new \DateTime(), true));
+        $blogPost = new BlogPost('Roger');
+        $blogPost->addComment(new Comment('comment by normal user', new \DateTime(), false));
+        $blogPost->addComment(new Comment('comment by admin', new \DateTime(), true));
 
         $this->dm->persist($blogPost);
         $this->dm->flush();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterGetShardKeyQueryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterGetShardKeyQueryTest.php
index 70f416c9c0..1d31ed15ee 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterGetShardKeyQueryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/DocumentPersisterGetShardKeyQueryTest.php
@@ -1,10 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Persisters;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Documents\User;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\UTCDateTime;
+use function get_class;
 
 class DocumentPersisterGetShardKeyQueryTest extends BaseTest
 {
@@ -23,7 +30,7 @@ public function testGetShardKeyQueryScalars()
         $method->setAccessible(true);
 
         $this->assertSame(
-            array('int' => $o->int, 'string' => $o->string, 'bool' => $o->bool, 'float' => $o->float),
+            ['int' => $o->int, 'string' => $o->string, 'bool' => $o->bool, 'float' => $o->float],
             $method->invoke($persister, $o)
         );
     }
@@ -42,13 +49,13 @@ public function testGetShardKeyQueryObjects()
         $method->setAccessible(true);
         $shardKeyQuery = $method->invoke($persister, $o);
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $shardKeyQuery['oid']);
+        $this->assertInstanceOf(ObjectId::class, $shardKeyQuery['oid']);
         $this->assertSame($o->oid, (string) $shardKeyQuery['oid']);
 
-        $this->assertInstanceOf(\MongoDB\BSON\Binary::class, $shardKeyQuery['bin']);
+        $this->assertInstanceOf(Binary::class, $shardKeyQuery['bin']);
         $this->assertSame($o->bin, $shardKeyQuery['bin']->getData());
 
-        $this->assertInstanceOf(\MongoDB\BSON\UTCDateTime::class, $shardKeyQuery['date']);
+        $this->assertInstanceOf(UTCDateTime::class, $shardKeyQuery['date']);
         $this->assertEquals($o->date->getTimestamp(), $shardKeyQuery['date']->toDateTime()->getTimestamp());
 
         $this->assertSame(
@@ -60,7 +67,7 @@ public function testGetShardKeyQueryObjects()
     public function testShardById()
     {
         $o = new ShardedById();
-        $o->identifier = new \MongoDB\BSON\ObjectId();
+        $o->identifier = new ObjectId();
 
         /** @var DocumentPersister $persister */
         $persister = $this->uow->getDocumentPersister(get_class($o));
@@ -69,15 +76,15 @@ public function testShardById()
         $method->setAccessible(true);
         $shardKeyQuery = $method->invoke($persister, $o);
 
-        $this->assertSame(array('_id' => $o->identifier), $shardKeyQuery);
+        $this->assertSame(['_id' => $o->identifier], $shardKeyQuery);
     }
 
     public function testShardByReference()
     {
         $o = new ShardedByReferenceOne();
 
-        $userId = new \MongoDB\BSON\ObjectId();
-        $o->reference = new \Documents\User();
+        $userId = new ObjectId();
+        $o->reference = new User();
         $o->reference->setId($userId);
 
         $this->dm->persist($o->reference);
@@ -89,7 +96,7 @@ public function testShardByReference()
         $method->setAccessible(true);
         $shardKeyQuery = $method->invoke($persister, $o);
 
-        $this->assertSame(array('reference.$id' => $userId), $shardKeyQuery);
+        $this->assertSame(['reference.$id' => $userId], $shardKeyQuery);
     }
 }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/PersistenceBuilderTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/PersistenceBuilderTest.php
index 53c80c587b..92d1daec0f 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Persisters/PersistenceBuilderTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Persisters/PersistenceBuilderTest.php
@@ -1,15 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Persisters;
 
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
+use Doctrine\ODM\MongoDB\Query\Builder;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
-use Documents\Ecommerce\Currency;
-use Documents\Ecommerce\ConfigurableProduct;
 use Documents\CmsArticle;
 use Documents\CmsComment;
+use Documents\Ecommerce\ConfigurableProduct;
+use Documents\Ecommerce\Currency;
 use Documents\Functional\SameCollection1;
 use Documents\Functional\SameCollection2;
+use MongoDB\BSON\ObjectId;
+use function array_keys;
+use function get_class;
 
 class PersistenceBuilderTest extends BaseTest
 {
@@ -39,7 +45,7 @@ public function testQueryBuilderUpdateWithDiscriminatorMap()
         $this->uow->computeChangeSets();
 
         /**
-         * @var \Doctrine\ODM\MongoDB\Query\Builder $qb
+         * @var Builder $qb
          */
         $qb = $this->dm->createQueryBuilder('Documents\Functional\SameCollection1');
         $qb->updateOne()
@@ -60,11 +66,11 @@ public function testFindWithOrOnCollectionWithDiscriminatorMap()
         $sameCollection1 = new SameCollection1();
         $sameCollection2a = new SameCollection2();
         $sameCollection2b = new SameCollection2();
-        $ids = array(
+        $ids = [
             '4f28aa84acee413889000001',
             '4f28aa84acee41388900002a',
-            '4f28aa84acee41388900002b'
-        );
+            '4f28aa84acee41388900002b',
+        ];
 
         $sameCollection1->id = $ids[0];
         $sameCollection1->name = 'First entry in SameCollection1';
@@ -87,7 +93,7 @@ public function testFindWithOrOnCollectionWithDiscriminatorMap()
         $this->uow->computeChangeSets();
 
         /**
-         * @var \Doctrine\ODM\MongoDB\Query\Builder $qb
+         * @var Builder $qb
          */
         $qb = $this->dm->createQueryBuilder(SameCollection2::class);
         $qb
@@ -136,12 +142,12 @@ public function testPrepareInsertDataWithCreatedReferenceOne()
         $this->dm->persist($comment);
         $this->uow->computeChangeSets();
 
-        $expectedData = array(
-            'article' => array(
-                '$id' => new \MongoDB\BSON\ObjectId($article->id),
-                '$ref' => 'CmsArticle'
-            )
-        );
+        $expectedData = [
+            'article' => [
+                '$id' => new ObjectId($article->id),
+                '$ref' => 'CmsArticle',
+            ],
+        ];
         $this->assertDocumentInsertData($expectedData, $this->pb->prepareInsertData($comment));
     }
 
@@ -160,12 +166,12 @@ public function testPrepareInsertDataWithFetchedReferenceOne()
         $this->dm->persist($comment);
         $this->uow->computeChangeSets();
 
-        $expectedData = array(
-            'article' => array(
-                '$id' => new \MongoDB\BSON\ObjectId($article->id),
-                '$ref' => 'CmsArticle'
-            )
-        );
+        $expectedData = [
+            'article' => [
+                '$id' => new ObjectId($article->id),
+                '$ref' => 'CmsArticle',
+            ],
+        ];
         $this->assertDocumentInsertData($expectedData, $this->pb->prepareInsertData($comment));
     }
 
@@ -186,17 +192,17 @@ public function testPrepareUpsertData()
         $this->dm->persist($comment);
         $this->uow->computeChangeSets();
 
-        $expectedData = array(
-            '$set' => array(
+        $expectedData = [
+            '$set' => [
                 'topic' => 'test',
                 'text' => 'text',
-                'article' => array(
-                    '$id' => new \MongoDB\BSON\ObjectId($article->id),
-                    '$ref' => 'CmsArticle'
-                ),
-                '_id' => new \MongoDB\BSON\ObjectId($comment->id),
-            )
-        );
+                'article' => [
+                    '$id' => new ObjectId($article->id),
+                    '$ref' => 'CmsArticle',
+                ],
+                '_id' => new ObjectId($comment->id),
+            ],
+        ];
         $this->assertEquals($expectedData, $this->pb->prepareUpsertData($comment));
     }
 
@@ -218,22 +224,22 @@ public function testPrepareInsertData($document, array $expectedData)
      */
     public function getDocumentsAndExpectedData()
     {
-        return array(
-            array(new ConfigurableProduct('Test Product'), array('name' => 'Test Product')),
-            array(new Currency('USD', 1), array('name' => 'USD', 'multiplier' => 1)),
-        );
+        return [
+            [new ConfigurableProduct('Test Product'), ['name' => 'Test Product']],
+            [new Currency('USD', 1), ['name' => 'USD', 'multiplier' => 1]],
+        ];
     }
 
-    private function assertDocumentInsertData(array $expectedData, array $preparedData = null)
+    private function assertDocumentInsertData(array $expectedData, ?array $preparedData = null)
     {
         foreach ($preparedData as $key => $value) {
             if ($key === '_id') {
-                $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $value);
+                $this->assertInstanceOf(ObjectId::class, $value);
                 continue;
             }
             $this->assertEquals($expectedData[$key], $value);
         }
-        if ( ! isset($preparedData['_id'])) {
+        if (! isset($preparedData['_id'])) {
             $this->fail('insert data should always contain id');
         }
         unset($preparedData['_id']);
@@ -260,11 +266,11 @@ public function testAdvancedQueriesOnReferenceWithDiscriminatorMap()
         $commentId = (string) $comment->id;
 
         /**
-         * @var \Doctrine\ODM\MongoDB\Query\Builder $qb
+         * @var Builder $qb
          */
         $qb = $this->dm->createQueryBuilder('Documents\CmsComment');
         $qb
-            ->field('article.id')->in(array($articleId));
+            ->field('article.id')->in([$articleId]);
         $query = $qb->getQuery();
         $results = $query->execute();
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/BuilderTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/BuilderTest.php
index 81ccf10d91..936156b186 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/BuilderTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/BuilderTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -12,7 +14,7 @@
 use Documents\User;
 use GeoJson\Geometry\Geometry;
 use GeoJson\Geometry\Point;
-use MongoDB\Collection;
+use MongoDB\BSON\ObjectId;
 use MongoDB\Driver\ReadPreference;
 
 class BuilderTest extends BaseTest
@@ -35,13 +37,13 @@ public function testReferencesGoesThroughDiscriminatorMap()
             ->field('featureFull')->references($f)
             ->getQuery()->debug();
 
-        $this->assertEquals([ 'featureFull.$id' => new \MongoDB\BSON\ObjectId($f->id) ], $q1['query']);
+        $this->assertEquals([ 'featureFull.$id' => new ObjectId($f->id) ], $q1['query']);
 
         $q2 = $this->dm->createQueryBuilder(ParentClass::class)
             ->field('featureSimple')->references($f)
             ->getQuery()->debug();
 
-        $this->assertEquals([ 'featureSimple' => new \MongoDB\BSON\ObjectId($f->id) ], $q2['query']);
+        $this->assertEquals([ 'featureSimple' => new ObjectId($f->id) ], $q2['query']);
 
         $q3 = $this->dm->createQueryBuilder(ParentClass::class)
             ->field('featurePartial')->references($f)
@@ -49,7 +51,7 @@ public function testReferencesGoesThroughDiscriminatorMap()
 
         $this->assertEquals(
             [
-                'featurePartial.$id' => new \MongoDB\BSON\ObjectId($f->id),
+                'featurePartial.$id' => new ObjectId($f->id),
                 'featurePartial.$ref' => 'Feature',
             ],
             $q3['query']
@@ -93,13 +95,13 @@ public function testIncludesReferenceToGoesThroughDiscriminatorMap()
             ->field('featureFullMany')->includesReferenceTo($f)
             ->getQuery()->debug();
 
-        $this->assertEquals([ 'featureFullMany' => [ '$elemMatch' => [ '$id' => new \MongoDB\BSON\ObjectId($f->id) ] ] ], $q1['query']);
+        $this->assertEquals([ 'featureFullMany' => [ '$elemMatch' => [ '$id' => new ObjectId($f->id) ] ] ], $q1['query']);
 
         $q2 = $this->dm->createQueryBuilder(ParentClass::class)
             ->field('featureSimpleMany')->includesReferenceTo($f)
             ->getQuery()->debug();
 
-        $this->assertEquals([ 'featureSimpleMany' => new \MongoDB\BSON\ObjectId($f->id) ], $q2['query']);
+        $this->assertEquals([ 'featureSimpleMany' => new ObjectId($f->id) ], $q2['query']);
 
         $q3 = $this->dm->createQueryBuilder(ParentClass::class)
             ->field('featurePartialMany')->includesReferenceTo($f)
@@ -109,10 +111,10 @@ public function testIncludesReferenceToGoesThroughDiscriminatorMap()
             [
                 'featurePartialMany' => [
                     '$elemMatch' => [
-                        '$id' => new \MongoDB\BSON\ObjectId($f->id),
+                        '$id' => new ObjectId($f->id),
                         '$ref' => 'Feature',
-                    ]
-                ]
+                    ],
+                ],
             ],
             $q3['query']
         );
@@ -295,10 +297,12 @@ public function testThatOrAcceptsAnotherQuery()
         $qb->addOr($qb->expr()->field('firstName')->equals('Kris'));
         $qb->addOr($qb->expr()->field('firstName')->equals('Chris'));
 
-        $this->assertEquals(['$or' => [
+        $this->assertEquals([
+        '$or' => [
             ['firstName' => 'Kris'],
-            ['firstName' => 'Chris']
-        ]], $qb->getQueryArray());
+            ['firstName' => 'Chris'],
+        ],
+        ], $qb->getQueryArray());
     }
 
     public function testThatAndAcceptsAnotherQuery()
@@ -321,19 +325,23 @@ public function testThatNorAcceptsAnotherQuery()
         $qb->addNor($qb->expr()->field('firstName')->equals('Kris'));
         $qb->addNor($qb->expr()->field('firstName')->equals('Chris'));
 
-        $this->assertEquals(['$nor' => [
+        $this->assertEquals([
+        '$nor' => [
             ['firstName' => 'Kris'],
-            ['firstName' => 'Chris']
-        ]], $qb->getQueryArray());
+            ['firstName' => 'Chris'],
+        ],
+        ], $qb->getQueryArray());
     }
 
     public function testAddElemMatch()
     {
         $qb = $this->getTestQueryBuilder();
         $qb->field('phonenumbers')->elemMatch($qb->expr()->field('phonenumber')->equals('6155139185'));
-        $expected = ['phonenumbers' => [
-            '$elemMatch' => ['phonenumber' => '6155139185']
-        ]];
+        $expected = [
+        'phonenumbers' => [
+            '$elemMatch' => ['phonenumber' => '6155139185'],
+        ],
+        ];
         $this->assertEquals($expected, $qb->getQueryArray());
     }
 
@@ -344,9 +352,9 @@ public function testAddNot()
         $expected = [
             'username' => [
                 '$not' => [
-                    '$in' => ['boo']
-                ]
-            ]
+                    '$in' => ['boo'],
+                ],
+            ],
         ];
         $this->assertEquals($expected, $qb->getQueryArray());
     }
@@ -355,9 +363,7 @@ public function testFindQuery()
     {
         $qb = $this->getTestQueryBuilder()
             ->where("function() { return this.username == 'boo' }");
-        $expected = [
-            '$where' => "function() { return this.username == 'boo' }"
-        ];
+        $expected = ['$where' => "function() { return this.username == 'boo' }"];
         $this->assertEquals($expected, $qb->getQueryArray());
     }
 
@@ -369,9 +375,7 @@ public function testUpsertUpdateQuery()
             ->field('username')->set('jwage');
 
         $expected = [
-            '$set' => [
-                'username' => 'jwage'
-            ]
+            '$set' => ['username' => 'jwage'],
         ];
         $this->assertEquals($expected, $qb->getNewObj());
         $this->assertTrue($qb->debug('upsert'));
@@ -384,9 +388,7 @@ public function testMultipleUpdateQuery()
             ->field('username')->set('jwage');
 
         $expected = [
-            '$set' => [
-                'username' => 'jwage'
-            ]
+            '$set' => ['username' => 'jwage'],
         ];
         $this->assertEquals($expected, $qb->getNewObj());
         $this->assertTrue($qb->debug('multiple'));
@@ -400,14 +402,12 @@ public function testComplexUpdateQuery()
             ->set('jwage')
             ->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$set' => [
-            'username' => 'jwage'
-        ]];
+        $expected = [
+        '$set' => ['username' => 'jwage'],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -418,14 +418,12 @@ public function testIncUpdateQuery()
             ->field('hits')->inc(5)
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$inc' => [
-            'hits' => 5
-        ]];
+        $expected = [
+        '$inc' => ['hits' => 5],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -436,14 +434,12 @@ public function testUnsetField()
             ->field('hits')->unsetField()
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$unset' => [
-            'hits' => 1
-        ]];
+        $expected = [
+        '$unset' => ['hits' => 1],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -456,14 +452,14 @@ public function testSetOnInsert()
             ->field('username')->equals('boo')
             ->field('createDate')->setOnInsert($createDate);
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$setOnInsert' => [
+        $expected = [
+        '$setOnInsert' => [
             'createDate' => (Type::getType('date'))->convertToDatabaseValue($createDate),
-        ]];
+        ],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -478,7 +474,7 @@ public function testDateRange()
             'createdAt' => [
                 '$gte' => Type::getType('date')->convertToDatabaseValue($start),
                 '$lt' => Type::getType('date')->convertToDatabaseValue($end),
-            ]
+            ],
         ];
         $this->assertEquals($expected, $qb->getQueryArray());
     }
@@ -809,14 +805,14 @@ public function testCurrentDateUpdateQuery($type)
             ->field('lastUpdated')->currentDate($type)
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$currentDate' => [
-            'lastUpdated' => ['$type' => $type]
-        ]];
+        $expected = [
+        '$currentDate' => [
+            'lastUpdated' => ['$type' => $type],
+        ],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -824,7 +820,7 @@ public static function provideCurrentDateOptions()
     {
         return [
             ['date'],
-            ['timestamp']
+            ['timestamp'],
         ];
     }
 
@@ -845,14 +841,14 @@ public function testBitAndUpdateQuery()
             ->field('flags')->bitAnd(15)
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$bit' => [
-            'flags' => ['and' => 15]
-        ]];
+        $expected = [
+        '$bit' => [
+            'flags' => ['and' => 15],
+        ],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -863,14 +859,14 @@ public function testBitOrUpdateQuery()
             ->field('flags')->bitOr(15)
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$bit' => [
-            'flags' => ['or' => 15]
-        ]];
+        $expected = [
+        '$bit' => [
+            'flags' => ['or' => 15],
+        ],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
@@ -881,14 +877,14 @@ public function testBitXorUpdateQuery()
             ->field('flags')->bitXor(15)
             ->field('username')->equals('boo');
 
-        $expected = [
-            'username' => 'boo'
-        ];
+        $expected = ['username' => 'boo'];
         $this->assertEquals($expected, $qb->getQueryArray());
 
-        $expected = ['$bit' => [
-            'flags' => ['xor' => 15]
-        ]];
+        $expected = [
+        '$bit' => [
+            'flags' => ['xor' => 15],
+        ],
+        ];
         $this->assertEquals($expected, $qb->getNewObj());
     }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/CriteriaMergerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/CriteriaMergerTest.php
index 685d4c4911..d4e286049c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/CriteriaMergerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/CriteriaMergerTest.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query;
 
 use Doctrine\ODM\MongoDB\Query\CriteriaMerger;
 use PHPUnit\Framework\TestCase;
+use function call_user_func_array;
 
 class CriteriaMergerTest extends TestCase
 {
@@ -12,40 +15,40 @@ class CriteriaMergerTest extends TestCase
      */
     public function testMerge(array $args, array $merged)
     {
-        $this->assertSame($merged, call_user_func_array(array(new CriteriaMerger(), 'merge'), $args));
+        $this->assertSame($merged, call_user_func_array([new CriteriaMerger(), 'merge'], $args));
     }
 
     public function provideMerge()
     {
-        return array(
-            'no args' => array(
-                array(),
-                array(),
-            ),
-            'one arg returned as-is' => array(
-                array(array('x' => 1)),
-                array('x' => 1),
-            ),
-            'empty criteria arrays are ignored' => array(
-                array(array('x' => 1), array()),
-                array('x' => 1),
-            ),
-            'two identical args' => array(
-                array(array('x' => 1), array('x' => 1)),
-                array('$and' => array(array('x' => 1), array('x' => 1))),
-            ),
-            'two different args' => array(
-                array(array('x' => 1), array('y' => 1)),
-                array('$and' => array(array('x' => 1), array('y' => 1))),
-            ),
-            'two conflicting args' => array(
-                array(array('x' => 1), array('x' => 2)),
-                array('$and' => array(array('x' => 1), array('x' => 2))),
-            ),
-            'existing $and criteria gets nested' => array(
-                array(array('$and' => array(array('x' => 1))), array('x' => 1)),
-                array('$and' => array(array('$and' => array(array('x' => 1))), array('x' => 1))),
-            ),
-        );
+        return [
+            'no args' => [
+                [],
+                [],
+            ],
+            'one arg returned as-is' => [
+                [['x' => 1]],
+                ['x' => 1],
+            ],
+            'empty criteria arrays are ignored' => [
+                [['x' => 1], []],
+                ['x' => 1],
+            ],
+            'two identical args' => [
+                [['x' => 1], ['x' => 1]],
+                ['$and' => [['x' => 1], ['x' => 1]]],
+            ],
+            'two different args' => [
+                [['x' => 1], ['y' => 1]],
+                ['$and' => [['x' => 1], ['y' => 1]]],
+            ],
+            'two conflicting args' => [
+                [['x' => 1], ['x' => 2]],
+                ['$and' => [['x' => 1], ['x' => 2]]],
+            ],
+            'existing $and criteria gets nested' => [
+                [['$and' => [['x' => 1]]], ['x' => 1]],
+                ['$and' => [['$and' => [['x' => 1]]], ['x' => 1]]],
+            ],
+        ];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/ExprTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/ExprTest.php
index bbe2f59774..833e947575 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/ExprTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/ExprTest.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Persisters\DocumentPersister;
 use Doctrine\ODM\MongoDB\Query\Expr;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\UnitOfWork;
 use Documents\User;
+use MongoDB\BSON\ObjectId;
 
-class ExprTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ExprTest extends BaseTest
 {
     public function testSelectIsPrepared()
     {
@@ -17,12 +21,12 @@ public function testSelectIsPrepared()
             ->select('id');
         $query = $qb->getQuery();
 
-        $this->assertEquals(array('_id' => 1), $query->debug('select'));
+        $this->assertEquals(['_id' => 1], $query->debug('select'));
     }
 
     public function testInIsPrepared()
     {
-        $ids = array('4f28aa84acee41388900000a');
+        $ids = ['4f28aa84acee41388900000a'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->field('groups.id')->in($ids)
@@ -30,13 +34,13 @@ public function testInIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$in'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$in'][0]);
         $this->assertEquals($ids[0], (string) $debug['groups.$id']['$in'][0]);
     }
 
     public function testAllIsPrepared()
     {
-        $ids = array('4f28aa84acee41388900000a');
+        $ids = ['4f28aa84acee41388900000a'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->field('groups.id')->all($ids)
@@ -44,7 +48,7 @@ public function testAllIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$all'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$all'][0]);
         $this->assertEquals($ids[0], (string) $debug['groups.$id']['$all'][0]);
     }
 
@@ -58,13 +62,13 @@ public function testNotEqualIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$ne']);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$ne']);
         $this->assertEquals($id, (string) $debug['groups.$id']['$ne']);
     }
 
     public function testNotInIsPrepared()
     {
-        $ids = array('4f28aa84acee41388900000a');
+        $ids = ['4f28aa84acee41388900000a'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->field('groups.id')->notIn($ids)
@@ -72,13 +76,13 @@ public function testNotInIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$nin'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$nin'][0]);
         $this->assertEquals($ids[0], (string) $debug['groups.$id']['$nin'][0]);
     }
 
     public function testAndIsPrepared()
     {
-        $ids = array('4f28aa84acee41388900000a');
+        $ids = ['4f28aa84acee41388900000a'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User');
         $qb
@@ -87,13 +91,13 @@ public function testAndIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['$and'][0]['groups.$id']['$in'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['$and'][0]['groups.$id']['$in'][0]);
         $this->assertEquals($ids[0], (string) $debug['$and'][0]['groups.$id']['$in'][0]);
     }
 
     public function testOrIsPrepared()
     {
-        $ids = array('4f28aa84acee41388900000a');
+        $ids = ['4f28aa84acee41388900000a'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User');
         $qb
@@ -102,16 +106,16 @@ public function testOrIsPrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['$or'][0]['groups.$id']['$in'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['$or'][0]['groups.$id']['$in'][0]);
         $this->assertEquals($ids[0], (string) $debug['$or'][0]['groups.$id']['$in'][0]);
     }
 
     public function testMultipleQueryOperatorsArePrepared()
     {
-        $all = array('4f28aa84acee41388900000a');
-        $in = array('4f28aa84acee41388900000b');
+        $all = ['4f28aa84acee41388900000a'];
+        $in = ['4f28aa84acee41388900000b'];
         $ne = '4f28aa84acee41388900000c';
-        $nin = array('4f28aa84acee41388900000d');
+        $nin = ['4f28aa84acee41388900000d'];
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->field('groups.id')->all($all)
@@ -122,13 +126,13 @@ public function testMultipleQueryOperatorsArePrepared()
         $query = $qb->getQuery();
         $debug = $query->debug('query');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$all'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$all'][0]);
         $this->assertEquals($all[0], (string) $debug['groups.$id']['$all'][0]);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$in'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$in'][0]);
         $this->assertEquals($in[0], (string) $debug['groups.$id']['$in'][0]);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$ne']);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$ne']);
         $this->assertEquals($ne, (string) $debug['groups.$id']['$ne']);
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $debug['groups.$id']['$nin'][0]);
+        $this->assertInstanceOf(ObjectId::class, $debug['groups.$id']['$nin'][0]);
         $this->assertEquals($nin[0], (string) $debug['groups.$id']['$nin'][0]);
     }
 
@@ -138,7 +142,7 @@ public function testPrepareNestedDocuments()
             ->field('address.subAddress.subAddress.subAddress.test')->equals('test');
         $query = $qb->getQuery();
         $debug = $query->debug('query');
-        $this->assertEquals(array('address.subAddress.subAddress.subAddress.testFieldName' => 'test'), $debug);
+        $this->assertEquals(['address.subAddress.subAddress.subAddress.testFieldName' => 'test'], $debug);
     }
 
     public function testPreparePositionalOperator()
@@ -146,10 +150,10 @@ public function testPreparePositionalOperator()
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->updateOne()
             ->field('phonenumbers.$.phonenumber')->equals('foo')
-            ->field('phonenumbers.$')->set(array('phonenumber' => 'bar'));
+            ->field('phonenumbers.$')->set(['phonenumber' => 'bar']);
 
-        $this->assertEquals(array('phonenumbers.$.phonenumber' => 'foo'), $qb->getQueryArray());
-        $this->assertEquals(array('$set' => array('phonenumbers.$' => array('phonenumber' => 'bar'))), $qb->getNewObj());
+        $this->assertEquals(['phonenumbers.$.phonenumber' => 'foo'], $qb->getQueryArray());
+        $this->assertEquals(['$set' => ['phonenumbers.$' => ['phonenumber' => 'bar']]], $qb->getNewObj());
     }
 
     public function testSortIsPrepared()
@@ -158,22 +162,22 @@ public function testSortIsPrepared()
             ->sort('id', 'desc');
         $query = $qb->getQuery();
         $query = $query->getQuery();
-        $this->assertEquals(array('_id' => -1), $query['sort']);
+        $this->assertEquals(['_id' => -1], $query['sort']);
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->sort('address.subAddress.subAddress.subAddress.test', 'asc');
         $query = $qb->getQuery();
         $query = $query->getQuery();
-        $this->assertEquals(array('address.subAddress.subAddress.subAddress.testFieldName' => 1), $query['sort']);
+        $this->assertEquals(['address.subAddress.subAddress.subAddress.testFieldName' => 1], $query['sort']);
     }
 
     public function testNestedWithOperator()
     {
         $qb = $this->dm->createQueryBuilder('Documents\User')
-            ->field('address.subAddress.subAddress.subAddress.test')->notIn(array('test'));
+            ->field('address.subAddress.subAddress.subAddress.test')->notIn(['test']);
         $query = $qb->getQuery();
         $query = $query->getQuery();
-        $this->assertEquals(array('address.subAddress.subAddress.subAddress.testFieldName' => array('$nin' => array('test'))), $query['query']);
+        $this->assertEquals(['address.subAddress.subAddress.subAddress.testFieldName' => ['$nin' => ['test']]], $query['query']);
     }
 
     public function testNewObjectIsPrepared()
@@ -183,7 +187,7 @@ public function testNewObjectIsPrepared()
             ->field('address.subAddress.subAddress.subAddress.test')->popFirst();
         $query = $qb->getQuery();
         $query = $query->getQuery();
-        $this->assertEquals(array('$pop' => array('address.subAddress.subAddress.subAddress.testFieldName' => 1)), $query['newObj']);
+        $this->assertEquals(['$pop' => ['address.subAddress.subAddress.subAddress.testFieldName' => 1]], $query['newObj']);
     }
 
     public function testReferencesUsesMinimalKeys()
@@ -193,12 +197,12 @@ public function testReferencesUsesMinimalKeys()
         $documentPersister = $this->createMock(DocumentPersister::class);
         $class = $this->createMock(ClassMetadata::class);
 
-        $expected = array('foo.$id' => '1234');
+        $expected = ['foo.$id' => '1234'];
 
         $dm
             ->expects($this->once())
             ->method('createReference')
-            ->will($this->returnValue(array('$ref' => 'coll', '$id' => '1234', '$db' => 'db')));
+            ->will($this->returnValue(['$ref' => 'coll', '$id' => '1234', '$db' => 'db']));
         $dm
             ->expects($this->once())
             ->method('getUnitOfWork')
@@ -218,7 +222,7 @@ public function testReferencesUsesMinimalKeys()
         $class
             ->expects($this->once())
             ->method('getFieldMapping')
-            ->will($this->returnValue(array('targetDocument' => 'Foo', 'name' => 'foo', 'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB)));
+            ->will($this->returnValue(['targetDocument' => 'Foo', 'name' => 'foo', 'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB]));
 
         $expr = $this->createExpr($dm, $class);
         $expr->field('bar')->references(new \stdClass());
@@ -233,12 +237,12 @@ public function testReferencesUsesAllKeys()
         $documentPersister = $this->createMock(DocumentPersister::class);
         $class = $this->createMock(ClassMetadata::class);
 
-        $expected = array('foo.$ref' => 'coll', 'foo.$id' => '1234', 'foo.$db' => 'db');
+        $expected = ['foo.$ref' => 'coll', 'foo.$id' => '1234', 'foo.$db' => 'db'];
 
         $dm
             ->expects($this->once())
             ->method('createReference')
-            ->will($this->returnValue(array('$ref' => 'coll', '$id' => '1234', '$db' => 'db')));
+            ->will($this->returnValue(['$ref' => 'coll', '$id' => '1234', '$db' => 'db']));
         $dm
             ->expects($this->once())
             ->method('getUnitOfWork')
@@ -258,7 +262,7 @@ public function testReferencesUsesAllKeys()
         $class
             ->expects($this->once())
             ->method('getFieldMapping')
-            ->will($this->returnValue(array('name' => 'foo', 'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB)));
+            ->will($this->returnValue(['name' => 'foo', 'storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF_WITH_DB]));
 
         $expr = $this->createExpr($dm, $class);
         $expr->field('bar')->references(new \stdClass());
@@ -273,12 +277,12 @@ public function testReferencesUsesSomeKeys()
         $documentPersister = $this->createMock(DocumentPersister::class);
         $class = $this->createMock(ClassMetadata::class);
 
-        $expected = array('foo.$ref' => 'coll', 'foo.$id' => '1234');
+        $expected = ['foo.$ref' => 'coll', 'foo.$id' => '1234'];
 
         $dm
             ->expects($this->once())
             ->method('createReference')
-            ->will($this->returnValue(array('$ref' => 'coll', '$id' => '1234')));
+            ->will($this->returnValue(['$ref' => 'coll', '$id' => '1234']));
         $dm
             ->expects($this->once())
             ->method('getUnitOfWork')
@@ -298,7 +302,7 @@ public function testReferencesUsesSomeKeys()
         $class
             ->expects($this->once())
             ->method('getFieldMapping')
-            ->will($this->returnValue(array('storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF, 'name' => 'foo')));
+            ->will($this->returnValue(['storeAs' => ClassMetadata::REFERENCE_STORE_AS_DB_REF, 'name' => 'foo']));
 
         $expr = $this->createExpr($dm, $class);
         $expr->field('bar')->references(new \stdClass());
@@ -548,11 +552,13 @@ public function testPushWithExpression()
             ->sort('x', 1);
 
         $expectedNewObj = [
-            '$push' => ['a' => [
+            '$push' => [
+        'a' => [
                 '$each' => [['x' => 1], ['x' => 2]],
                 '$slice' => -2,
                 '$sort' => ['x' => 1],
-            ]],
+            ],
+            ],
         ];
 
         $this->assertSame($expr, $expr->field('a')->push($innerExpr));
@@ -569,11 +575,13 @@ public function testPushWithExpressionShouldEnsureEachOperatorAppearsFirst()
             ->each([['x' => 1], ['x' => 2]]);
 
         $expectedNewObj = [
-            '$push' => ['a' => [
+            '$push' => [
+        'a' => [
                 '$each' => [['x' => 1], ['x' => 2]],
                 '$sort' => ['x' => 1],
                 '$slice' => -2,
-            ]],
+            ],
+            ],
         ];
 
         $this->assertSame($expr, $expr->field('a')->push($innerExpr));
@@ -589,10 +597,12 @@ public function testPushWithPosition()
             ->position(0);
 
         $expectedNewObj = [
-            '$push' => ['a' => [
+            '$push' => [
+        'a' => [
                 '$each' => [20, 30],
                 '$position' => 0,
-            ]],
+            ],
+            ],
         ];
 
         $this->assertSame($expr, $expr->field('a')->push($innerExpr));
@@ -743,9 +753,9 @@ public function testNotInWillStripKeysToYieldBsonArray()
         $this->assertEquals(['$nin' => ['value1', 'value2']], $expr->getQuery());
     }
 
-    private function createExpr(DocumentManager $dm = null, ClassMetadata $class = null): Expr
+    private function createExpr(?DocumentManager $dm = null, ?ClassMetadata $class = null): Expr
     {
-        if (!$dm) {
+        if (! $dm) {
             $dm = $this->createMock(DocumentManager::class);
             $uow = $this->createMock(UnitOfWork::class);
             $documentPersister = $this->createMock(DocumentPersister::class);
@@ -766,7 +776,7 @@ private function createExpr(DocumentManager $dm = null, ClassMetadata $class = n
                 ->will($this->returnArgument(0));
         }
 
-        if (!$class) {
+        if (! $class) {
             $class = new ClassMetadata(User::class);
         }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/BsonFilterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/BsonFilterTest.php
index 65c0aba9d3..f0efe8524a 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/BsonFilterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/BsonFilterTest.php
@@ -1,29 +1,33 @@
-<?php
-
-namespace Doctrine\ODM\MongoDB\Tests\Query\Filter;
-
-class BsonFilterTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
-{
-    /**
-     * @expectedException InvalidArgumentException
-     */
-    public function testGetParameterInvalidArgument()
-    {
-        $filter = new Filter($this->dm);
-        $filter->getParameter('doesnotexist');
-    }
-
-    public function testSetParameter()
-    {
-        $filter = new Filter($this->dm);
-        $filter->setParameter('username', 'Tim');
-        $this->assertEquals('Tim', $filter->getParameter('username'));
-    }
-
-    public function testGetNullParameter()
-    {
-        $filter = new Filter($this->dm);
-        $filter->setParameter('foo', null);
-        $this->assertNull($filter->getParameter('foo'));
-    }
-}
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\Query\Filter;
+
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+
+class BsonFilterTest extends BaseTest
+{
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testGetParameterInvalidArgument()
+    {
+        $filter = new Filter($this->dm);
+        $filter->getParameter('doesnotexist');
+    }
+
+    public function testSetParameter()
+    {
+        $filter = new Filter($this->dm);
+        $filter->setParameter('username', 'Tim');
+        $this->assertEquals('Tim', $filter->getParameter('username'));
+    }
+
+    public function testGetNullParameter()
+    {
+        $filter = new Filter($this->dm);
+        $filter->setParameter('foo', null);
+        $this->assertNull($filter->getParameter('foo'));
+    }
+}
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/Filter.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/Filter.php
index 8dce330fb5..360286fccc 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/Filter.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/Filter/Filter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query\Filter;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
@@ -9,8 +11,8 @@ class Filter extends BsonFilter
 {
     public function addFilterCriteria(ClassMetadata $class)
     {
-        return ($class->name == $this->parameters['class'])
-            ? array($this->parameters['field'] => $this->parameters['value'])
-            : array();
+        return ($class->name === $this->parameters['class'])
+            ? [$this->parameters['field'] => $this->parameters['value']]
+            : [];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/FilterCollectionTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/FilterCollectionTest.php
index 98c7e0b4c3..7718193dad 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/FilterCollectionTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/FilterCollectionTest.php
@@ -1,8 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query;
 
-class FilterCollectionTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+
+class FilterCollectionTest extends BaseTest
 {
     public function testEnable()
     {
@@ -71,7 +75,7 @@ public function testGetFilterCriteria()
         $testFilter->setParameter('field', 'username');
         $testFilter->setParameter('value', 'Tim');
 
-        $this->assertSame(array('username' => 'Tim'), $filterCollection->getFilterCriteria($class));
+        $this->assertSame(['username' => 'Tim'], $filterCollection->getFilterCriteria($class));
     }
 
     public function testGetFilterCriteriaMergesCriteria()
@@ -91,10 +95,12 @@ public function testGetFilterCriteriaMergesCriteria()
         $testFilter->setParameter('field', 'username');
         $testFilter->setParameter('value', 'John');
 
-        $expectedCriteria = array('$and' => array(
-            array('username' => 'Tim'),
-            array('username' => 'John'),
-        ));
+        $expectedCriteria = [
+        '$and' => [
+            ['username' => 'Tim'],
+            ['username' => 'John'],
+        ],
+        ];
 
         $this->assertSame($expectedCriteria, $filterCollection->getFilterCriteria($class));
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Query/QueryExpressionVisitorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Query/QueryExpressionVisitorTest.php
index dd0a48d913..2765db3e31 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Query/QueryExpressionVisitorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Query/QueryExpressionVisitorTest.php
@@ -1,13 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Query;
 
-use Doctrine\Common\Collections\ExpressionBuilder;
 use Doctrine\Common\Collections\Expr\Comparison;
 use Doctrine\Common\Collections\Expr\CompositeExpression;
 use Doctrine\Common\Collections\Expr\Value;
+use Doctrine\Common\Collections\ExpressionBuilder;
 use Doctrine\ODM\MongoDB\Query\QueryExpressionVisitor;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use MongoDB\BSON\Regex;
 
 class QueryExpressionVisitorTest extends BaseTest
 {
@@ -36,18 +39,18 @@ public function provideComparisons()
     {
         $builder = new ExpressionBuilder();
 
-        return array(
-            array($builder->eq('field', 'value'), array('field' => 'value')),
-            array($builder->contains('field', 'value'), array('field' => new \MongoDB\BSON\Regex('value', ''))),
-            array($builder->gt('field', 'value'), array('field' => array('$gt' => 'value'))),
-            array($builder->gte('field', 'value'), array('field' => array('$gte' => 'value'))),
-            array($builder->in('field', array(1, 2)), array('field' => array('$in' => array(1, 2)))),
-            array($builder->isNull('field'), array('field' => null)),
-            array($builder->lt('field', 'value'), array('field' => array('$lt' => 'value'))),
-            array($builder->lte('field', 'value'), array('field' => array('$lte' => 'value'))),
-            array($builder->neq('field', 'value'), array('field' => array('$ne' => 'value'))),
-            array($builder->notIn('field', array(1, 2)), array('field' => array('$nin' => array(1, 2)))),
-        );
+        return [
+            [$builder->eq('field', 'value'), ['field' => 'value']],
+            [$builder->contains('field', 'value'), ['field' => new Regex('value', '')]],
+            [$builder->gt('field', 'value'), ['field' => ['$gt' => 'value']]],
+            [$builder->gte('field', 'value'), ['field' => ['$gte' => 'value']]],
+            [$builder->in('field', [1, 2]), ['field' => ['$in' => [1, 2]]]],
+            [$builder->isNull('field'), ['field' => null]],
+            [$builder->lt('field', 'value'), ['field' => ['$lt' => 'value']]],
+            [$builder->lte('field', 'value'), ['field' => ['$lte' => 'value']]],
+            [$builder->neq('field', 'value'), ['field' => ['$ne' => 'value']]],
+            [$builder->notIn('field', [1, 2]), ['field' => ['$nin' => [1, 2]]]],
+        ];
     }
 
     /**
@@ -69,11 +72,13 @@ public function testWalkCompositeExpression()
             $builder->eq('b', 3)
         );
 
-        $expectedQuery = array('$and' => array(
-            array('a' => 1),
-            array('a' => array('$ne' => 2)),
-            array('b' => 3),
-        ));
+        $expectedQuery = [
+        '$and' => [
+            ['a' => 1],
+            ['a' => ['$ne' => 2]],
+            ['b' => 3],
+        ],
+        ];
 
         $expr = $this->visitor->dispatch($compositeExpr);
 
@@ -86,7 +91,7 @@ public function testWalkCompositeExpression()
      */
     public function testWalkCompositeExpressionShouldThrowExceptionForUnsupportedComposite()
     {
-        $compositeExpr = new CompositeExpression('invalidComposite', array());
+        $compositeExpr = new CompositeExpression('invalidComposite', []);
         $expr = $this->visitor->dispatch($compositeExpr);
     }
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/QueryLogger.php b/tests/Doctrine/ODM/MongoDB/Tests/QueryLogger.php
index 1cf73057c5..e2db203788 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/QueryLogger.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/QueryLogger.php
@@ -1,10 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
+use function count;
+
 class QueryLogger implements \Countable
 {
-    private $queries = array();
+    private $queries = [];
 
     /**
      * Log a query.
@@ -21,14 +25,14 @@ public function __invoke(array $query)
      */
     public function clear()
     {
-        $this->queries = array();
+        $this->queries = [];
     }
 
     /**
      * Returns the number of logged queries.
      *
      * @see php.net/countable.count
-     * @return integer
+     * @return int
      */
     public function count()
     {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/QueryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/QueryTest.php
index 175e5c7dc2..d602b436a1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/QueryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/QueryTest.php
@@ -1,22 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Query\Query;
+use Documents\SubProject;
 use Documents\User;
+use MongoDB\BSON\ObjectId;
 use MongoDB\Collection;
-use MongoDB\Database;
 use MongoDB\Driver\ReadPreference;
-use MongoDB\Model\CachingIterator;
+use const DOCTRINE_MONGODB_DATABASE;
+use function array_keys;
 
 class QueryTest extends BaseTest
 {
     public function testSelectAndSelectSliceOnSameField()
     {
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person')
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person')
             ->exclude('comments')
             ->select('comments')
             ->selectSlice('comments', 0, 10);
@@ -37,18 +41,20 @@ public function testThatOrAcceptsAnotherQuery()
         $this->dm->persist($chris);
         $this->dm->flush();
 
-        $class = __NAMESPACE__.'\Person';
-        $expression1 = array('firstName' => 'Kris');
-        $expression2 = array('firstName' => 'Chris');
+        $class = __NAMESPACE__ . '\Person';
+        $expression1 = ['firstName' => 'Kris'];
+        $expression2 = ['firstName' => 'Chris'];
 
         $qb = $this->dm->createQueryBuilder($class);
         $qb->addOr($qb->expr()->field('firstName')->equals('Kris'));
         $qb->addOr($qb->expr()->field('firstName')->equals('Chris'));
 
-        $this->assertEquals(array('$or' => array(
-            array('firstName' => 'Kris'),
-            array('firstName' => 'Chris')
-        )), $qb->getQueryArray());
+        $this->assertEquals([
+        '$or' => [
+            ['firstName' => 'Kris'],
+            ['firstName' => 'Chris'],
+        ],
+        ], $qb->getQueryArray());
 
         $query = $qb->getQuery();
         $users = $query->execute();
@@ -69,15 +75,15 @@ public function testReferences()
         $kris->bestFriend = $jon;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('bestFriend')->references($jon);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
+        $this->assertEquals([
             'bestFriend.$ref' => 'people',
-            'bestFriend.$id' => new \MongoDB\BSON\ObjectId($jon->id),
+            'bestFriend.$id' => new ObjectId($jon->id),
             'bestFriend.$db' => DOCTRINE_MONGODB_DATABASE,
-        ), $queryArray);
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -97,13 +103,13 @@ public function testReferencesStoreAsId()
         $kris->bestFriendSimple = $jon;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('bestFriendSimple')->references($jon);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
-            'bestFriendSimple' => new \MongoDB\BSON\ObjectId($jon->id),
-        ), $queryArray);
+        $this->assertEquals([
+            'bestFriendSimple' => new ObjectId($jon->id),
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -123,14 +129,14 @@ public function testReferencesStoreAsDbRef()
         $kris->bestFriendPartial = $jon;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('bestFriendPartial')->references($jon);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
+        $this->assertEquals([
             'bestFriendPartial.$ref' => 'people',
-            'bestFriendPartial.$id' => new \MongoDB\BSON\ObjectId($jon->id),
-        ), $queryArray);
+            'bestFriendPartial.$id' => new ObjectId($jon->id),
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -150,19 +156,19 @@ public function testIncludesReferenceToWithStoreAsDbRefWithDb()
         $jon->friends[] = $kris;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('friends')->includesReferenceTo($kris);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
-            'friends' => array(
-                '$elemMatch' => array(
+        $this->assertEquals([
+            'friends' => [
+                '$elemMatch' => [
                     '$ref' => 'people',
-                    '$id' => new \MongoDB\BSON\ObjectId($kris->id),
+                    '$id' => new ObjectId($kris->id),
                     '$db' => DOCTRINE_MONGODB_DATABASE,
-                ),
-            ),
-        ), $queryArray);
+                ],
+            ],
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -185,13 +191,13 @@ public function testIncludesReferenceToWithStoreAsId()
         $jon->friendsSimple[] = $jachim;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('friendsSimple')->includesReferenceTo($kris);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
-            'friendsSimple' =>  new \MongoDB\BSON\ObjectId($kris->id)
-        ), $queryArray);
+        $this->assertEquals([
+            'friendsSimple' =>  new ObjectId($kris->id),
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -211,18 +217,18 @@ public function testIncludesReferenceToWithStoreAsDbRef()
         $jon->friendsPartial[] = $kris;
         $this->dm->flush();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\Person');
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\Person');
         $qb->field('friendsPartial')->includesReferenceTo($kris);
 
         $queryArray = $qb->getQueryArray();
-        $this->assertEquals(array(
-            'friendsPartial' => array(
-                '$elemMatch' => array(
+        $this->assertEquals([
+            'friendsPartial' => [
+                '$elemMatch' => [
                     '$ref' => 'people',
-                    '$id' => new \MongoDB\BSON\ObjectId($kris->id)
-                ),
-            ),
-        ), $queryArray);
+                    '$id' => new ObjectId($kris->id),
+                ],
+            ],
+        ], $queryArray);
 
         $query = $qb->getQuery();
 
@@ -232,13 +238,13 @@ public function testIncludesReferenceToWithStoreAsDbRef()
 
     public function testQueryIdIn()
     {
-        $user = new \Documents\User();
+        $user = new User();
         $user->setUsername('jwage');
         $this->dm->persist($user);
         $this->dm->flush();
 
-        $identifier = new \MongoDB\BSON\ObjectId($user->getId());
-        $ids = array($identifier);
+        $identifier = new ObjectId($user->getId());
+        $ids = [$identifier];
 
         $qb = $this->dm->createQueryBuilder('Documents\User')
             ->field('_id')->in($ids);
@@ -254,7 +260,7 @@ public function testEmbeddedSet()
             ->field('testInt')->set('0')
             ->field('intfields.intone')->set('1')
             ->field('intfields.inttwo')->set('2');
-        $this->assertEquals(array('testInt' => 0, 'intfields' => array('intone' => 1, 'inttwo' => 2)), $qb->getNewObj());
+        $this->assertEquals(['testInt' => 0, 'intfields' => ['intone' => 1, 'inttwo' => 2]], $qb->getNewObj());
     }
 
     public function testElemMatch()
@@ -265,28 +271,27 @@ public function testElemMatch()
         $embeddedQb = $this->dm->createQueryBuilder('Documents\Phonenumber');
 
         $qb->field('phonenumbers')->elemMatch($embeddedQb->expr()
-            ->field('lastCalledBy.id')->equals($refId)
-        );
+            ->field('lastCalledBy.id')->equals($refId));
         $query = $qb->getQuery();
 
-        $expectedQuery = array('phonenumbers' => array('$elemMatch' => array('lastCalledBy.$id' => new \MongoDB\BSON\ObjectId($refId))));
+        $expectedQuery = ['phonenumbers' => ['$elemMatch' => ['lastCalledBy.$id' => new ObjectId($refId)]]];
         $this->assertEquals($expectedQuery, $query->debug('query'));
     }
 
     public function testQueryWithMultipleEmbeddedDocuments()
     {
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\EmbedTest')
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\EmbedTest')
             ->find()
             ->field('embeddedOne.embeddedOne.embeddedMany.embeddedOne.name')->equals('Foo');
         $query = $qb->getQuery();
-        $this->assertEquals(array('eO.eO.e1.eO.n' => 'Foo'), $query->debug('query'));
+        $this->assertEquals(['eO.eO.e1.eO.n' => 'Foo'], $query->debug('query'));
     }
 
     public function testQueryWithMultipleEmbeddedDocumentsAndReference()
     {
-        $identifier = new \MongoDB\BSON\ObjectId();
+        $identifier = new ObjectId();
 
-        $qb = $this->dm->createQueryBuilder(__NAMESPACE__.'\EmbedTest')
+        $qb = $this->dm->createQueryBuilder(__NAMESPACE__ . '\EmbedTest')
             ->find()
             ->field('embeddedOne.embeddedOne.embeddedMany.embeddedOne.pet.owner.id')->equals((string) $identifier);
         $query = $qb->getQuery();
@@ -298,14 +303,14 @@ public function testQueryWithMultipleEmbeddedDocumentsAndReference()
 
     public function testSelectVsSingleCollectionInheritance()
     {
-        $p = new \Documents\SubProject('SubProject');
+        $p = new SubProject('SubProject');
         $this->dm->persist($p);
         $this->dm->flush();
         $this->dm->clear();
 
         $test = $this->dm->createQueryBuilder()
                 ->find('Documents\Project')
-                ->select(array('name'))
+                ->select(['name'])
                 ->field('id')->equals($p->getId())
                 ->getQuery()->getSingleResult();
         $this->assertNotNull($test);
@@ -315,14 +320,14 @@ public function testSelectVsSingleCollectionInheritance()
 
     public function testEmptySelectVsSingleCollectionInheritance()
     {
-        $p = new \Documents\SubProject('SubProject');
+        $p = new SubProject('SubProject');
         $this->dm->persist($p);
         $this->dm->flush();
         $this->dm->clear();
 
         $test = $this->dm->createQueryBuilder()
                 ->find('Documents\Project')
-                ->select(array())
+                ->select([])
                 ->field('id')->equals($p->getId())
                 ->getQuery()->getSingleResult();
         $this->assertNotNull($test);
@@ -332,30 +337,30 @@ public function testEmptySelectVsSingleCollectionInheritance()
 
     public function testDiscriminatorFieldNotAddedWithoutHydration()
     {
-        $p = new \Documents\SubProject('SubProject');
+        $p = new SubProject('SubProject');
         $this->dm->persist($p);
         $this->dm->flush();
         $this->dm->clear();
 
         $test = $this->dm->createQueryBuilder()
                 ->find('Documents\Project')->hydrate(false)
-                ->select(array('name'))
+                ->select(['name'])
                 ->field('id')->equals($p->getId())
                 ->getQuery()->getSingleResult();
         $this->assertNotNull($test);
-        $this->assertEquals(array('_id', 'name'), array_keys($test));
+        $this->assertEquals(['_id', 'name'], array_keys($test));
     }
 
     public function testExcludeVsSingleCollectionInheritance()
     {
-        $p = new \Documents\SubProject('SubProject');
+        $p = new SubProject('SubProject');
         $this->dm->persist($p);
         $this->dm->flush();
         $this->dm->clear();
 
         $test = $this->dm->createQueryBuilder()
                 ->find('Documents\SubProject')
-                ->exclude(array('name', 'issues'))
+                ->exclude(['name', 'issues'])
                 ->field('id')->equals($p->getId())
                 ->getQuery()->getSingleResult();
         $this->assertNotNull($test);
@@ -499,13 +504,13 @@ class Person
     public $bestFriendPartial;
 
     /** @ODM\ReferenceMany(storeAs="dbRefWithDb") */
-    public $friends = array();
+    public $friends = [];
 
     /** @ODM\ReferenceMany(storeAs="id", targetDocument="Doctrine\ODM\MongoDB\Tests\Person") */
-    public $friendsSimple = array();
+    public $friendsSimple = [];
 
     /** @ODM\ReferenceMany */
-    public $friendsPartial = array();
+    public $friendsPartial = [];
 
     /** @ODM\EmbedOne(targetDocument="Pet") */
     public $pet;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/RepositoryFactoryTest.php b/tests/Doctrine/ODM/MongoDB/Tests/RepositoryFactoryTest.php
index e848d909b0..edd75f95db 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/RepositoryFactoryTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/RepositoryFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\DocumentManager;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/SchemaManagerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/SchemaManagerTest.php
index 5bc3eb9b04..88119f64d0 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/SchemaManagerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/SchemaManagerTest.php
@@ -1,36 +1,50 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
 use Doctrine\ODM\MongoDB\Configuration;
-use Doctrine\ODM\MongoDB\SchemaManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
 use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
+use Doctrine\ODM\MongoDB\SchemaManager;
 use Doctrine\ODM\MongoDB\Tests\Mocks\DocumentManagerMock;
+use Documents\CmsAddress;
+use Documents\CmsArticle;
+use Documents\CmsComment;
+use Documents\CmsGroup;
+use Documents\CmsPhonenumber;
+use Documents\CmsProduct;
+use Documents\CmsUser;
+use Documents\Comment;
+use Documents\Sharded\ShardedUser;
+use Documents\SimpleReferenceUser;
 use MongoDB\Client;
 use MongoDB\Collection;
 use MongoDB\Database;
 use MongoDB\Model\IndexInfoIteratorIterator;
 use PHPUnit\Framework\TestCase;
+use const DOCTRINE_MONGODB_DATABASE;
+use function in_array;
 
 class SchemaManagerTest extends TestCase
 {
-    private $indexedClasses = array(
-        \Documents\CmsAddress::class,
-        \Documents\CmsArticle::class,
-        \Documents\CmsComment::class,
-        \Documents\CmsProduct::class,
-        \Documents\Comment::class,
-        \Documents\SimpleReferenceUser::class,
-    );
-
-    private $someNonIndexedClasses = array(
-        \Documents\CmsGroup::class,
-        \Documents\CmsPhonenumber::class,
-        \Documents\CmsUser::class,
-    );
-
-    private $someMappedSuperclassAndEmbeddedClasses = array(
+    private $indexedClasses = [
+        CmsAddress::class,
+        CmsArticle::class,
+        CmsComment::class,
+        CmsProduct::class,
+        Comment::class,
+        SimpleReferenceUser::class,
+    ];
+
+    private $someNonIndexedClasses = [
+        CmsGroup::class,
+        CmsPhonenumber::class,
+        CmsUser::class,
+    ];
+
+    private $someMappedSuperclassAndEmbeddedClasses = [
         'Documents/BlogTagAggregation',
         'Documents/CmsContent',
         'Documents/CmsPage',
@@ -39,11 +53,11 @@ class SchemaManagerTest extends TestCase
         'Documents/Phonenumber',
         'Documents/Song',
         'Documents/SubCategory',
-    );
+    ];
 
-    private $classMetadatas = array();
-    private $documentCollections = array();
-    private $documentDatabases = array();
+    private $classMetadatas = [];
+    private $documentCollections = [];
+    private $documentDatabases = [];
 
     /**
      * @var SchemaManager
@@ -58,7 +72,7 @@ public function setUp()
         $cmf->setConfiguration($this->dm->getConfiguration());
         $cmf->setDocumentManager($this->dm);
 
-        $map = array();
+        $map = [];
 
         foreach ($cmf->getAllMetadata() as $cm) {
             $this->documentCollections[$cm->name] = $this->getMockCollection();
@@ -91,39 +105,39 @@ public function testEnsureIndexes()
     public function testEnsureDocumentIndexes()
     {
         foreach ($this->documentCollections as $class => $collection) {
-            if ($class === \Documents\CmsArticle::class) {
+            if ($class === CmsArticle::class) {
                 $collection->expects($this->once())->method('createIndex');
             } else {
                 $collection->expects($this->never())->method('createIndex');
             }
         }
 
-        $this->schemaManager->ensureDocumentIndexes(\Documents\CmsArticle::class);
+        $this->schemaManager->ensureDocumentIndexes(CmsArticle::class);
     }
 
     public function testEnsureDocumentIndexesWithTwoLevelInheritance()
     {
-        $collection = $this->documentCollections[\Documents\CmsProduct::class];
+        $collection = $this->documentCollections[CmsProduct::class];
         $collection->expects($this->once())->method('createIndex');
 
-        $this->schemaManager->ensureDocumentIndexes(\Documents\CmsProduct::class);
+        $this->schemaManager->ensureDocumentIndexes(CmsProduct::class);
     }
 
     public function testEnsureDocumentIndexesWithTimeout()
     {
-        $collection = $this->documentCollections[\Documents\CmsArticle::class];
+        $collection = $this->documentCollections[CmsArticle::class];
         $collection->expects($this->once())
             ->method('createIndex')
-            ->with($this->anything(), $this->callback(function($o) {
+            ->with($this->anything(), $this->callback(function ($o) {
                 return isset($o['timeout']) && $o['timeout'] === 10000;
             }));
 
-        $this->schemaManager->ensureDocumentIndexes(\Documents\CmsArticle::class, 10000);
+        $this->schemaManager->ensureDocumentIndexes(CmsArticle::class, 10000);
     }
 
     public function testUpdateDocumentIndexesShouldCreateMappedIndexes()
     {
-        $collection = $this->documentCollections[\Documents\CmsArticle::class];
+        $collection = $this->documentCollections[CmsArticle::class];
         $collection->expects($this->once())
             ->method('listIndexes')
             ->will($this->returnValue(new IndexInfoIteratorIterator(new \ArrayIterator([]))));
@@ -132,17 +146,18 @@ public function testUpdateDocumentIndexesShouldCreateMappedIndexes()
         $collection->expects($this->never())
             ->method('dropIndex');
 
-        $this->schemaManager->updateDocumentIndexes(\Documents\CmsArticle::class);
+        $this->schemaManager->updateDocumentIndexes(CmsArticle::class);
     }
 
     public function testUpdateDocumentIndexesShouldDeleteUnmappedIndexesBeforeCreatingMappedIndexes()
     {
-        $collection = $this->documentCollections[\Documents\CmsArticle::class];
+        $collection = $this->documentCollections[CmsArticle::class];
         $indexes = [[
             'v' => 1,
-            'key' => array('topic' => -1),
-            'name' => 'topic_-1'
-        ]];
+            'key' => ['topic' => -1],
+            'name' => 'topic_-1',
+        ],
+        ];
         $collection->expects($this->once())
             ->method('listIndexes')
             ->will($this->returnValue(new IndexInfoIteratorIterator(new \ArrayIterator($indexes))));
@@ -151,7 +166,7 @@ public function testUpdateDocumentIndexesShouldDeleteUnmappedIndexesBeforeCreati
         $collection->expects($this->once())
             ->method('dropIndex');
 
-        $this->schemaManager->updateDocumentIndexes(\Documents\CmsArticle::class);
+        $this->schemaManager->updateDocumentIndexes(CmsArticle::class);
     }
 
     public function testDeleteIndexes()
@@ -170,24 +185,24 @@ public function testDeleteIndexes()
     public function testDeleteDocumentIndexes()
     {
         foreach ($this->documentCollections as $class => $collection) {
-            if ($class === \Documents\CmsArticle::class) {
+            if ($class === CmsArticle::class) {
                 $collection->expects($this->once())->method('dropIndexes');
             } else {
                 $collection->expects($this->never())->method('dropIndexes');
             }
         }
 
-        $this->schemaManager->deleteDocumentIndexes(\Documents\CmsArticle::class);
+        $this->schemaManager->deleteDocumentIndexes(CmsArticle::class);
     }
 
     public function testCreateDocumentCollection()
     {
-        $cm = $this->classMetadatas[\Documents\CmsArticle::class];
+        $cm = $this->classMetadatas[CmsArticle::class];
         $cm->collectionCapped = true;
         $cm->collectionSize = 1048576;
         $cm->collectionMax = 32;
 
-        $database = $this->documentDatabases[\Documents\CmsArticle::class];
+        $database = $this->documentDatabases[CmsArticle::class];
         $database->expects($this->once())
             ->method('createCollection')
             ->with(
@@ -195,12 +210,12 @@ public function testCreateDocumentCollection()
                 [
                     'capped' => true,
                     'size' => 1048576,
-                    'max' => 32
+                    'max' => 32,
                 ]
             )
         ;
 
-        $this->schemaManager->createDocumentCollection(\Documents\CmsArticle::class);
+        $this->schemaManager->createDocumentCollection(CmsArticle::class);
     }
 
     public function testCreateCollections()
@@ -234,7 +249,7 @@ public function testDropCollections()
     public function testDropDocumentCollection()
     {
         foreach ($this->documentCollections as $class => $collection) {
-            if ($class === \Documents\CmsArticle::class) {
+            if ($class === CmsArticle::class) {
                 $collection->expects($this->once())
                     ->method('drop')
                     ->with();
@@ -243,20 +258,20 @@ public function testDropDocumentCollection()
             }
         }
 
-        $this->schemaManager->dropDocumentCollection(\Documents\CmsArticle::class);
+        $this->schemaManager->dropDocumentCollection(CmsArticle::class);
     }
 
     public function testDropDocumentDatabase()
     {
         foreach ($this->documentDatabases as $class => $database) {
-            if ($class === \Documents\CmsArticle::class) {
+            if ($class === CmsArticle::class) {
                 $database->expects($this->once())->method('drop');
             } else {
                 $database->expects($this->never())->method('drop');
             }
         }
 
-        $this->dm->getSchemaManager()->dropDocumentDatabase(\Documents\CmsArticle::class);
+        $this->dm->getSchemaManager()->dropDocumentDatabase(CmsArticle::class);
     }
 
     public function testDropDatabases()
@@ -278,7 +293,7 @@ public function testDropDatabases()
     public function testIsMongoIndexEquivalentToDocumentIndex($expected, $mongoIndex, $documentIndex)
     {
         $defaultMongoIndex = [
-            'key' => ['foo' => 1, 'bar' => -1]
+            'key' => ['foo' => 1, 'bar' => -1],
         ];
         $defaultDocumentIndex = [
             'keys' => ['foo' => 1, 'bar' => -1],
@@ -445,7 +460,7 @@ public function dataIsMongoIndexEquivalentToDocumentIndex()
                 'expected' => true,
                 'mongoIndex' => ['partialFilterExpression' => []],
                 'documentIndex' => [],
-            ]
+            ],
         ];
     }
 
@@ -454,7 +469,7 @@ public function testEnsureDocumentSharding()
         $this->markTestSkipped('Sharding support is still WIP');
 
         $dbName = DOCTRINE_MONGODB_DATABASE;
-        $classMetadata = $this->dm->getClassMetadata(\Documents\Sharded\ShardedUser::class);
+        $classMetadata = $this->dm->getClassMetadata(ShardedUser::class);
         $collectionName = $classMetadata->getCollection();
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn($dbName);
@@ -462,18 +477,18 @@ public function testEnsureDocumentSharding()
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
-        $this->dm->documentDatabases = array($classMetadata->getName() => $dbMock);
+        $this->dm->documentDatabases = [$classMetadata->getName() => $dbMock];
 
         $adminDBMock
             ->expects($this->at(0))
             ->method('command')
-            ->with(array('enableSharding' => $dbName))
-            ->willReturn(array('ok' => 1));
+            ->with(['enableSharding' => $dbName])
+            ->willReturn(['ok' => 1]);
         $adminDBMock
             ->expects($this->at(1))
             ->method('command')
-            ->with(array('shardCollection' => $dbName . '.' . $collectionName, 'key' => array('_id' => 'hashed')))
-            ->willReturn(array('ok' => 1));
+            ->with(['shardCollection' => $dbName . '.' . $collectionName, 'key' => ['_id' => 'hashed']])
+            ->willReturn(['ok' => 1]);
 
         $this->schemaManager->ensureDocumentSharding($classMetadata->getName());
     }
@@ -487,7 +502,7 @@ public function testEnsureDocumentShardingThrowsExceptionIfThereWasAnError()
         $this->markTestSkipped('Sharding support is still WIP');
 
         $dbName = DOCTRINE_MONGODB_DATABASE;
-        $classMetadata = $this->dm->getClassMetadata(\Documents\Sharded\ShardedUser::class);
+        $classMetadata = $this->dm->getClassMetadata(ShardedUser::class);
         $collectionName = $classMetadata->getCollection();
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn($dbName);
@@ -495,18 +510,18 @@ public function testEnsureDocumentShardingThrowsExceptionIfThereWasAnError()
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
-        $this->dm->documentDatabases = array($classMetadata->getName() => $dbMock);
+        $this->dm->documentDatabases = [$classMetadata->getName() => $dbMock];
 
         $adminDBMock
             ->expects($this->at(0))
             ->method('command')
-            ->with(array('enableSharding' => $dbName))
-            ->willReturn(array('ok' => 1));
+            ->with(['enableSharding' => $dbName])
+            ->willReturn(['ok' => 1]);
         $adminDBMock
             ->expects($this->at(1))
             ->method('command')
-            ->with(array('shardCollection' => $dbName . '.' . $collectionName, 'key' => array('_id' => 'hashed')))
-            ->willReturn(array('ok' => 0, 'code' => 666, 'errmsg' => 'Scary error'));
+            ->with(['shardCollection' => $dbName . '.' . $collectionName, 'key' => ['_id' => 'hashed']])
+            ->willReturn(['ok' => 0, 'code' => 666, 'errmsg' => 'Scary error']);
 
         $this->schemaManager->ensureDocumentSharding($classMetadata->getName());
     }
@@ -516,7 +531,7 @@ public function testEnsureDocumentShardingIgnoresAlreadyShardedError()
         $this->markTestSkipped('Sharding support is still WIP');
 
         $dbName = DOCTRINE_MONGODB_DATABASE;
-        $classMetadata = $this->dm->getClassMetadata(\Documents\Sharded\ShardedUser::class);
+        $classMetadata = $this->dm->getClassMetadata(ShardedUser::class);
         $collectionName = $classMetadata->getCollection();
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn($dbName);
@@ -524,18 +539,18 @@ public function testEnsureDocumentShardingIgnoresAlreadyShardedError()
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
-        $this->dm->documentDatabases = array($classMetadata->getName() => $dbMock);
+        $this->dm->documentDatabases = [$classMetadata->getName() => $dbMock];
 
         $adminDBMock
             ->expects($this->at(0))
             ->method('command')
-            ->with(array('enableSharding' => $dbName))
-            ->willReturn(array('ok' => 1));
+            ->with(['enableSharding' => $dbName])
+            ->willReturn(['ok' => 1]);
         $adminDBMock
             ->expects($this->at(1))
             ->method('command')
-            ->with(array('shardCollection' => $dbName . '.' . $collectionName, 'key' => array('_id' => 'hashed')))
-            ->willReturn(array('ok' => 0, 'code' => 20, 'errmsg' => 'already sharded'));
+            ->with(['shardCollection' => $dbName . '.' . $collectionName, 'key' => ['_id' => 'hashed']])
+            ->willReturn(['ok' => 0, 'code' => 20, 'errmsg' => 'already sharded']);
 
         $this->schemaManager->ensureDocumentSharding($classMetadata->getName());
     }
@@ -548,16 +563,16 @@ public function testEnableShardingForDb()
         $adminDBMock
             ->expects($this->once())
             ->method('command')
-            ->with(array('enableSharding' => 'db'))
-            ->willReturn(array('ok' => 1));
+            ->with(['enableSharding' => 'db'])
+            ->willReturn(['ok' => 1]);
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn('db');
-        $this->dm->documentDatabases = array(\Documents\Sharded\ShardedUser::class => $dbMock);
+        $this->dm->documentDatabases = [ShardedUser::class => $dbMock];
 
-        $this->schemaManager->enableShardingForDbByDocumentName(\Documents\Sharded\ShardedUser::class);
+        $this->schemaManager->enableShardingForDbByDocumentName(ShardedUser::class);
     }
 
     /**
@@ -572,16 +587,16 @@ public function testEnableShardingForDbThrowsExceptionInCaseOfError()
         $adminDBMock
             ->expects($this->once())
             ->method('command')
-            ->with(array('enableSharding' => 'db'))
-            ->willReturn(array('ok' => 0, 'code' => 666, 'errmsg' => 'Scary error'));
+            ->with(['enableSharding' => 'db'])
+            ->willReturn(['ok' => 0, 'code' => 666, 'errmsg' => 'Scary error']);
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn('db');
-        $this->dm->documentDatabases = array(\Documents\Sharded\ShardedUser::class => $dbMock);
+        $this->dm->documentDatabases = [ShardedUser::class => $dbMock];
 
-        $this->schemaManager->enableShardingForDbByDocumentName(\Documents\Sharded\ShardedUser::class);
+        $this->schemaManager->enableShardingForDbByDocumentName(ShardedUser::class);
     }
 
     public function testEnableShardingForDbIgnoresAlreadyShardedError()
@@ -592,16 +607,16 @@ public function testEnableShardingForDbIgnoresAlreadyShardedError()
         $adminDBMock
             ->expects($this->once())
             ->method('command')
-            ->with(array('enableSharding' => 'db'))
-            ->willReturn(array('ok' => 0, 'code' => 23, 'errmsg' => 'already enabled'));
+            ->with(['enableSharding' => 'db'])
+            ->willReturn(['ok' => 0, 'code' => 23, 'errmsg' => 'already enabled']);
         $connMock = $this->getMockClient();
         $connMock->method('selectDatabase')->with('admin')->willReturn($adminDBMock);
         $this->dm->connection = $connMock;
         $dbMock = $this->getMockDatabase();
         $dbMock->method('getName')->willReturn('db');
-        $this->dm->documentDatabases = array(\Documents\Sharded\ShardedUser::class => $dbMock);
+        $this->dm->documentDatabases = [ShardedUser::class => $dbMock];
 
-        $this->schemaManager->enableShardingForDbByDocumentName(\Documents\Sharded\ShardedUser::class);
+        $this->schemaManager->enableShardingForDbByDocumentName(ShardedUser::class);
     }
 
     private function getMockCollection()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/BaseUser.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/BaseUser.php
index 4306e5ae71..88e26ead73 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/BaseUser.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/BaseUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH1299;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/GH1299User.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/GH1299User.php
index 0165e394bf..a5a44437b1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/GH1299User.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH1299/GH1299User.php
@@ -1,9 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH1299;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-use Doctrine\ODM\MongoDB\Tests\Tools\GH1299\BaseUser;
 
 /** @ODM\Document */
 class GH1299User extends BaseUser
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
index 8aefc77c3e..764e90d982 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH297;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -9,12 +11,12 @@ class Address
 {
     /** @ODM\Field(type="string") */
     private $street;
-    
+
     public function getStreet()
     {
         return $this->street;
     }
-    
+
     public function setStreet($street)
     {
         $this->street = $street;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/AddressTrait.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/AddressTrait.php
index 0c0a990c1d..2585303f0d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/AddressTrait.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/AddressTrait.php
@@ -1,20 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH297;
 
-trait AddressTrait 
+trait AddressTrait
 {
     /**
      * @ODM\EmbedOne
      */
     private $address;
 
-    public function getAddress() 
+    public function getAddress()
     {
         return $this->address;
     }
 
-    public function setAddress(Address $address) 
+    public function setAddress(Address $address)
     {
         $this->address = $address;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Admin.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Admin.php
index 8791448237..fedea6f7ac 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Admin.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Admin.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH297;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -7,5 +9,4 @@
 /** @ODM\Document */
 class Admin extends User
 {
-    
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/User.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/User.php
index d2cc23d304..5dd5274f0e 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/User.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/User.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools\GH297;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -8,23 +10,23 @@
 class User
 {
     use AddressTrait;
-    
+
     /** @ODM\Id */
     private $id;
-    
+
     /** @ODM\Field(type="string") */
     private $name;
-    
+
     public function getId()
     {
         return $this->id;
     }
-    
+
     public function getName()
     {
         return $this->name;
     }
-    
+
     public function setName($name)
     {
         $this->name = $name;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
index 0f267bd050..95422f954b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Tools;
 
+use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Events;
-use Doctrine\ODM\MongoDB\Tools\ResolveTargetDocumentListener;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Doctrine\ODM\MongoDB\Tools\ResolveTargetDocumentListener;
 
-class ResolveTargetDocumentListenerTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class ResolveTargetDocumentListenerTest extends BaseTest
 {
     /**
-     * @var \Doctrine\ODM\MongoDB\DocumentManager
+     * @var DocumentManager
      */
     protected $dm;
 
@@ -32,13 +36,13 @@ public function testResolveTargetDocumentListenerCanResolveTargetDocument()
         $this->listener->addResolveTargetDocument(
             'Doctrine\ODM\MongoDB\Tests\Tools\ResolveTargetInterface',
             'Doctrine\ODM\MongoDB\Tests\Tools\ResolveTargetDocument',
-            array()
+            []
         );
 
         $this->listener->addResolveTargetDocument(
             'Doctrine\ODM\MongoDB\Tests\Tools\TargetInterface',
             'Doctrine\ODM\MongoDB\Tests\Tools\TargetDocument',
-            array()
+            []
         );
 
         $evm->addEventListener(Events::loadClassMetadata, $this->listener);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Types/DateTypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Types/DateTypeTest.php
index a7cc8e8c07..2e27cc13aa 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Types/DateTypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Types/DateTypeTest.php
@@ -1,9 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Types;
 
 use Doctrine\ODM\MongoDB\Types\Type;
+use MongoDB\BSON\UTCDateTime;
 use PHPUnit\Framework\TestCase;
+use const PHP_INT_SIZE;
+use function call_user_func;
+use function date;
+use function strtotime;
 
 class DateTypeTest extends TestCase
 {
@@ -15,7 +22,7 @@ public function testGetDateTime()
         $dateTime = $type->getDateTime($timestamp);
         $this->assertEquals($timestamp, $dateTime->format('U.u'));
 
-        $mongoDate = new \MongoDB\BSON\UTCDateTime(100000000001);
+        $mongoDate = new UTCDateTime(100000000001);
         $dateTime = $type->getDateTime($mongoDate);
         $this->assertEquals($timestamp, $dateTime->format('U.u'));
     }
@@ -26,12 +33,12 @@ public function testConvertToDatabaseValue()
 
         $this->assertNull($type->convertToDatabaseValue(null), 'null is not converted');
 
-        $mongoDate = new \MongoDB\BSON\UTCDateTime();
+        $mongoDate = new UTCDateTime();
         $this->assertSame($mongoDate, $type->convertToDatabaseValue($mongoDate), 'MongoDate objects are not converted');
 
         $timestamp = 100000000.123;
-        $dateTime = \DateTime::createFromFormat('U.u', $timestamp);
-        $mongoDate = new \MongoDB\BSON\UTCDateTime(100000000123);
+        $dateTime = \DateTime::createFromFormat('U.u', (string) $timestamp);
+        $mongoDate = new UTCDateTime(100000000123);
         $this->assertEquals($mongoDate, $type->convertToDatabaseValue($dateTime), 'DateTime objects are converted to MongoDate objects');
         $this->assertEquals($mongoDate, $type->convertToDatabaseValue($timestamp), 'Numeric timestamps are converted to MongoDate objects');
         $this->assertEquals($mongoDate, $type->convertToDatabaseValue('' . $timestamp), 'String dates are converted to MongoDate objects');
@@ -44,9 +51,9 @@ public function testConvertDateTimeImmutable()
         $type = Type::getType(Type::DATE);
 
         $timestamp = 100000000.123;
-        $mongoDate = new \MongoDB\BSON\UTCDateTime(100000000123);
+        $mongoDate = new UTCDateTime(100000000123);
 
-        $dateTimeImmutable = \DateTimeImmutable::createFromFormat('U.u', $timestamp);
+        $dateTimeImmutable = \DateTimeImmutable::createFromFormat('U.u', (string) $timestamp);
         $this->assertEquals($mongoDate, $type->convertToDatabaseValue($dateTimeImmutable), 'DateTimeImmutable objects are converted to MongoDate objects');
     }
 
@@ -55,7 +62,7 @@ public function testConvertOldDate()
         $type = Type::getType(Type::DATE);
 
         $date = new \DateTime('1900-01-01 00:00:00.123', new \DateTimeZone('UTC'));
-        $timestamp = "-2208988800.123";
+        $timestamp = '-2208988800.123';
         $this->assertEquals($type->convertToDatabaseValue($timestamp), $type->convertToDatabaseValue($date));
     }
 
@@ -71,13 +78,13 @@ public function testConvertToDatabaseValueWithInvalidValues($value)
 
     public function provideInvalidDateValues()
     {
-        return array(
-            'array'  => array(array()),
-            'string' => array('whatever'),
-            'bool'   => array(false),
-            'object' => array(new \stdClass()),
-            'invalid string' => array('foo'),
-        );
+        return [
+            'array'  => [[]],
+            'string' => ['whatever'],
+            'bool'   => [false],
+            'object' => [new \stdClass()],
+            'invalid string' => ['foo'],
+        ];
     }
 
     /**
@@ -107,7 +114,7 @@ public function testClosureToPHP($input, $output)
         $type = Type::getType(Type::DATE);
         $return = null;
 
-        call_user_func(function($value) use ($type, &$return) {
+        call_user_func(function ($value) use ($type, &$return) {
             eval($type->closureToPHP());
         }, $input);
 
@@ -118,16 +125,16 @@ public function testClosureToPHP($input, $output)
     public function provideDatabaseToPHPValues()
     {
         $yesterday = strtotime('yesterday');
-        $mongoDate = new \MongoDB\BSON\UTCDateTime($yesterday * 1000);
+        $mongoDate = new UTCDateTime($yesterday * 1000);
         $dateTime = new \DateTime('@' . $yesterday);
 
-        return array(
-            array($dateTime, $dateTime),
-            array($mongoDate, $dateTime),
-            array($yesterday, $dateTime),
-            array(date('c', $yesterday), $dateTime),
-            array(new \MongoDB\BSON\UTCDateTime(100000000123), \DateTime::createFromFormat('U.u', '100000000.123')),
-        );
+        return [
+            [$dateTime, $dateTime],
+            [$mongoDate, $dateTime],
+            [$yesterday, $dateTime],
+            [date('c', $yesterday), $dateTime],
+            [new UTCDateTime(100000000123), \DateTime::createFromFormat('U.u', '100000000.123')],
+        ];
     }
 
     /**
@@ -136,7 +143,7 @@ public function provideDatabaseToPHPValues()
     public function test32bit1900Date()
     {
         if (PHP_INT_SIZE !== 4) {
-            $this->markTestSkipped("Platform is not 32-bit");
+            $this->markTestSkipped('Platform is not 32-bit');
         }
 
         $type = Type::getType(Type::DATE);
@@ -146,14 +153,14 @@ public function test32bit1900Date()
     public function test64bit1900Date()
     {
         if (PHP_INT_SIZE !== 8) {
-            $this->markTestSkipped("Platform is not 64-bit");
+            $this->markTestSkipped('Platform is not 64-bit');
         }
 
         $type = Type::getType(Type::DATE);
         $return = $type->convertToDatabaseValue('1900-01-01');
 
-        $this->assertInstanceOf(\MongoDB\BSON\UTCDateTime::class, $return);
-        $this->assertEquals(new \MongoDB\BSON\UTCDateTime(strtotime('1900-01-01') * 1000), $return);
+        $this->assertInstanceOf(UTCDateTime::class, $return);
+        $this->assertEquals(new UTCDateTime(strtotime('1900-01-01') * 1000), $return);
     }
 
     private function assertTimestampEquals(\DateTime $expected, \DateTime $actual)
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Types/IdTypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Types/IdTypeTest.php
index 5ab85f6dea..f4a1579cde 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Types/IdTypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Types/IdTypeTest.php
@@ -1,15 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Types;
 
 use Doctrine\ODM\MongoDB\Types\Type;
+use MongoDB\BSON\ObjectId;
 use PHPUnit\Framework\TestCase;
 
 class IdTypeTest extends TestCase
 {
     public function testConvertToDatabaseValue()
     {
-        $identifier = new \MongoDB\BSON\ObjectId();
+        $identifier = new ObjectId();
         $type = Type::getType('id');
 
         $this->assertNull($type->convertToDatabaseValue(null), 'null is not converted');
@@ -24,17 +27,16 @@ public function testConvertToDatabaseValueShouldGenerateObjectIds($value)
     {
         $type = Type::getType('id');
 
-        $this->assertInstanceOf(\MongoDB\BSON\ObjectId::class, $type->convertToDatabaseValue($value));
+        $this->assertInstanceOf(ObjectId::class, $type->convertToDatabaseValue($value));
     }
 
     public function provideInvalidObjectIdConstructorArguments()
     {
-        return array(
-            'integer' => array(1),
-            'float'   => array(3.14),
-            'string'  => array('string'),
-            'bool'    => array(true),
-            'object'  => array(array('x' => 1, 'y' => 2)),
-        );
+        return [
+            'integer' => [1],
+            'float'   => [3.14],
+            'string'  => ['string'],
+            'bool'    => [true],
+        ];
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Types/InvalidValueExceptionTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Types/InvalidValueExceptionTest.php
index 668a7e0862..8e9f444da9 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Types/InvalidValueExceptionTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Types/InvalidValueExceptionTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Types;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Types/TypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Types/TypeTest.php
index cb1c55f23d..2cc4e7a369 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Types/TypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Types/TypeTest.php
@@ -1,10 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests\Types;
 
+use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Doctrine\ODM\MongoDB\Types\Type;
+use MongoDB\BSON\Binary;
+use MongoDB\BSON\ObjectId;
+use MongoDB\BSON\Timestamp;
+use MongoDB\BSON\UTCDateTime;
+use const STR_PAD_LEFT;
+use function md5;
+use function str_pad;
+use function str_repeat;
+use function time;
 
-class TypeTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+class TypeTest extends BaseTest
 {
     /**
      * @dataProvider provideTypes
@@ -16,31 +28,31 @@ public function testConversion(Type $type, $test)
 
     public function provideTypes()
     {
-        return array(
-            'id' => array(Type::getType(Type::ID), "507f1f77bcf86cd799439011"),
-            'intId' => array(Type::getType(Type::INTID), 1),
-            'customId' => array(Type::getType(Type::CUSTOMID), (object) array('foo' => 'bar')),
-            'bool' => array(Type::getType(Type::BOOL), true),
-            'boolean' => array(Type::getType(Type::BOOLEAN), false),
-            'int' => array(Type::getType(Type::INT), 69),
-            'integer' => array(Type::getType(Type::INTEGER), 42),
-            'float' => array(Type::getType(Type::FLOAT), 3.14),
-            'string' => array(Type::getType(Type::STRING), 'ohai'),
-            'minKey' => array(Type::getType(Type::KEY), 0),
-            'maxKey' => array(Type::getType(Type::KEY), 1),
-            'timestamp' => array(Type::getType(Type::TIMESTAMP), time()),
-            'binData' => array(Type::getType(Type::BINDATA), 'foobarbaz'),
-            'binDataFunc' => array(Type::getType(Type::BINDATAFUNC), 'foobarbaz'),
-            'binDataByteArray' => array(Type::getType(Type::BINDATABYTEARRAY), 'foobarbaz'),
-            'binDataUuid' => array(Type::getType(Type::BINDATAUUID), "testtesttesttest"),
-            'binDataUuidRFC4122' => array(Type::getType(Type::BINDATAUUIDRFC4122), str_repeat('a', 16)),
-            'binDataMD5' => array(Type::getType(Type::BINDATAMD5), md5('ODM')),
-            'binDataCustom' => array(Type::getType(Type::BINDATACUSTOM), 'foobarbaz'),
-            'hash' => array(Type::getType(Type::HASH), array('foo' => 'bar')),
-            'collection' => array(Type::getType(Type::COLLECTION), array('foo', 'bar')),
-            'objectId' => array(Type::getType(Type::OBJECTID), "507f1f77bcf86cd799439011"),
-            'raw' => array(Type::getType(Type::RAW), (object) array('foo' => 'bar')),
-       );
+        return [
+            'id' => [Type::getType(Type::ID), '507f1f77bcf86cd799439011'],
+            'intId' => [Type::getType(Type::INTID), 1],
+            'customId' => [Type::getType(Type::CUSTOMID), (object) ['foo' => 'bar']],
+            'bool' => [Type::getType(Type::BOOL), true],
+            'boolean' => [Type::getType(Type::BOOLEAN), false],
+            'int' => [Type::getType(Type::INT), 69],
+            'integer' => [Type::getType(Type::INTEGER), 42],
+            'float' => [Type::getType(Type::FLOAT), 3.14],
+            'string' => [Type::getType(Type::STRING), 'ohai'],
+            'minKey' => [Type::getType(Type::KEY), 0],
+            'maxKey' => [Type::getType(Type::KEY), 1],
+            'timestamp' => [Type::getType(Type::TIMESTAMP), time()],
+            'binData' => [Type::getType(Type::BINDATA), 'foobarbaz'],
+            'binDataFunc' => [Type::getType(Type::BINDATAFUNC), 'foobarbaz'],
+            'binDataByteArray' => [Type::getType(Type::BINDATABYTEARRAY), 'foobarbaz'],
+            'binDataUuid' => [Type::getType(Type::BINDATAUUID), 'testtesttesttest'],
+            'binDataUuidRFC4122' => [Type::getType(Type::BINDATAUUIDRFC4122), str_repeat('a', 16)],
+            'binDataMD5' => [Type::getType(Type::BINDATAMD5), md5('ODM')],
+            'binDataCustom' => [Type::getType(Type::BINDATACUSTOM), 'foobarbaz'],
+            'hash' => [Type::getType(Type::HASH), ['foo' => 'bar']],
+            'collection' => [Type::getType(Type::COLLECTION), ['foo', 'bar']],
+            'objectId' => [Type::getType(Type::OBJECTID), '507f1f77bcf86cd799439011'],
+            'raw' => [Type::getType(Type::RAW), (object) ['foo' => 'bar']],
+        ];
     }
 
     /**
@@ -53,19 +65,19 @@ public function testConversionIsIdempotent(Type $type, $test)
 
     public function provideTypesForIdempotent()
     {
-        return array(
-            'id' => array(Type::getType(Type::ID), new \MongoDB\BSON\ObjectId()),
-            'date' => array(Type::getType(Type::DATE), new \MongoDB\BSON\UTCDateTime()),
-            'timestamp' => array(Type::getType(Type::TIMESTAMP), new \MongoDB\BSON\Timestamp(0, time())),
-            'binData' => array(Type::getType(Type::BINDATA), new \MongoDB\BSON\Binary('foobarbaz', \MongoDB\BSON\Binary::TYPE_GENERIC)),
-            'binDataFunc' => array(Type::getType(Type::BINDATAFUNC), new \MongoDB\BSON\Binary('foobarbaz', \MongoDB\BSON\Binary::TYPE_FUNCTION)),
-            'binDataByteArray' => array(Type::getType(Type::BINDATABYTEARRAY), new \MongoDB\BSON\Binary('foobarbaz', \MongoDB\BSON\Binary::TYPE_OLD_BINARY)),
-            'binDataUuid' => array(Type::getType(Type::BINDATAUUID), new \MongoDB\BSON\Binary("testtesttesttest", \MongoDB\BSON\Binary::TYPE_OLD_UUID)),
-            'binDataUuidRFC4122' => array(Type::getType(Type::BINDATAUUIDRFC4122), new \MongoDB\BSON\Binary(str_repeat('a', 16), \MongoDB\BSON\Binary::TYPE_UUID)),
-            'binDataMD5' => array(Type::getType(Type::BINDATAMD5), new \MongoDB\BSON\Binary(md5('ODM'), \MongoDB\BSON\Binary::TYPE_MD5)),
-            'binDataCustom' => array(Type::getType(Type::BINDATACUSTOM), new \MongoDB\BSON\Binary('foobarbaz', \MongoDB\BSON\Binary::TYPE_USER_DEFINED)),
-            'objectId' => array(Type::getType(Type::OBJECTID), new \MongoDB\BSON\ObjectId()),
-        );
+        return [
+            'id' => [Type::getType(Type::ID), new ObjectId()],
+            'date' => [Type::getType(Type::DATE), new UTCDateTime()],
+            'timestamp' => [Type::getType(Type::TIMESTAMP), new Timestamp(0, time())],
+            'binData' => [Type::getType(Type::BINDATA), new Binary('foobarbaz', Binary::TYPE_GENERIC)],
+            'binDataFunc' => [Type::getType(Type::BINDATAFUNC), new Binary('foobarbaz', Binary::TYPE_FUNCTION)],
+            'binDataByteArray' => [Type::getType(Type::BINDATABYTEARRAY), new Binary('foobarbaz', Binary::TYPE_OLD_BINARY)],
+            'binDataUuid' => [Type::getType(Type::BINDATAUUID), new Binary('testtesttesttest', Binary::TYPE_OLD_UUID)],
+            'binDataUuidRFC4122' => [Type::getType(Type::BINDATAUUIDRFC4122), new Binary(str_repeat('a', 16), Binary::TYPE_UUID)],
+            'binDataMD5' => [Type::getType(Type::BINDATAMD5), new Binary(md5('ODM'), Binary::TYPE_MD5)],
+            'binDataCustom' => [Type::getType(Type::BINDATACUSTOM), new Binary('foobarbaz', Binary::TYPE_USER_DEFINED)],
+            'objectId' => [Type::getType(Type::OBJECTID), new ObjectId()],
+        ];
     }
 
     public function testConvertDatePreservesMilliseconds()
@@ -74,7 +86,7 @@ public function testConvertDatePreservesMilliseconds()
         $expectedDate = clone $date;
 
         $cleanMicroseconds = (int) $date->format('v') * 1000;
-        $expectedDate->modify($date->format('H:i:s') . '.' . str_pad($cleanMicroseconds, 6, '0', STR_PAD_LEFT));
+        $expectedDate->modify($date->format('H:i:s') . '.' . str_pad((string) $cleanMicroseconds, 6, '0', STR_PAD_LEFT));
 
         $type = Type::getType(Type::DATE);
         $this->assertEquals($expectedDate, $type->convertToPHPValue($type->convertToDatabaseValue($date)));
@@ -84,6 +96,6 @@ public function testConvertImmutableDate()
     {
         $date = new \DateTimeImmutable('now');
 
-        $this->assertInstanceOf(\MongoDB\BSON\UTCDateTime::class, Type::convertPHPToDatabaseValue($date));
+        $this->assertInstanceOf(UTCDateTime::class, Type::convertPHPToDatabaseValue($date));
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php b/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
index 819831c770..9b4d21e6c1 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
@@ -1,19 +1,34 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Doctrine\ODM\MongoDB\Tests;
 
-use Doctrine\Common\PropertyChangedListener;
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\EventManager;
+use Doctrine\Common\NotifyPropertyChanged;
+use Doctrine\Common\PropertyChangedListener;
 use Doctrine\ODM\MongoDB\DocumentManager;
-use Doctrine\ODM\MongoDB\UnitOfWork;
+use Doctrine\ODM\MongoDB\Hydrator\HydratorFactory;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
 use Doctrine\ODM\MongoDB\Persisters\PersistenceBuilder;
 use Doctrine\ODM\MongoDB\Tests\Mocks\DocumentPersisterMock;
-use Documents\ForumUser;
+use Doctrine\ODM\MongoDB\Tests\Mocks\ExceptionThrowingListenerMock;
+use Doctrine\ODM\MongoDB\Tests\Mocks\PreUpdateListenerMock;
+use Doctrine\ODM\MongoDB\UnitOfWork;
+use Documents\Address;
+use Documents\CmsPhonenumber;
 use Documents\ForumAvatar;
-
-class UnitOfWorkTest extends \Doctrine\ODM\MongoDB\Tests\BaseTest
+use Documents\ForumUser;
+use Documents\Functional\NotSaved;
+use Documents\User;
+use MongoDB\BSON\ObjectId;
+use function get_class;
+use function spl_object_hash;
+use function ucfirst;
+
+class UnitOfWorkTest extends BaseTest
 {
     public function testIsDocumentScheduled()
     {
@@ -37,7 +52,7 @@ public function testScheduleForUpsert()
     {
         $class = $this->dm->getClassMetadata('Documents\ForumUser');
         $user = new ForumUser();
-        $user->id = new \MongoDB\BSON\ObjectId();
+        $user->id = new ObjectId();
         $this->assertFalse($this->uow->isScheduledForInsert($user));
         $this->assertFalse($this->uow->isScheduledForUpsert($user));
         $this->uow->scheduleForUpsert($class, $user);
@@ -49,17 +64,17 @@ public function testGetScheduledDocumentUpserts()
     {
         $class = $this->dm->getClassMetadata('Documents\ForumUser');
         $user = new ForumUser();
-        $user->id = new \MongoDB\BSON\ObjectId();
+        $user->id = new ObjectId();
         $this->assertEmpty($this->uow->getScheduledDocumentUpserts());
         $this->uow->scheduleForUpsert($class, $user);
-        $this->assertEquals(array(spl_object_hash($user) => $user), $this->uow->getScheduledDocumentUpserts());
+        $this->assertEquals([spl_object_hash($user) => $user], $this->uow->getScheduledDocumentUpserts());
     }
 
     public function testScheduleForEmbeddedUpsert()
     {
         $class = $this->dm->getClassMetadata('Documents\ForumUser');
         $test = new EmbeddedUpsertDocument();
-        $test->id = (string) new \MongoDB\BSON\ObjectId();
+        $test->id = (string) new ObjectId();
         $this->assertFalse($this->uow->isScheduledForInsert($test));
         $this->assertFalse($this->uow->isScheduledForUpsert($test));
         $this->uow->persist($test);
@@ -208,7 +223,7 @@ public function testChangeTrackingNotify()
         $entity->setTransient('newtransientvalue');
 
         $this->assertTrue($this->uow->isScheduledForDirtyCheck($entity));
-        $this->assertEquals(array('data' => array('thedata', 'newdata')), $this->uow->getDocumentChangeSet($entity));
+        $this->assertEquals(['data' => ['thedata', 'newdata']], $this->uow->getDocumentChangeSet($entity));
 
         $item = new NotifyChangedRelatedItem();
         $item->setId(1);
@@ -241,11 +256,11 @@ public function testChangeTrackingNotify()
     public function testGetDocumentStateWithAssignedIdentity()
     {
         $pb = $this->getMockPersistenceBuilder();
-        $class = $this->dm->getClassMetadata("Documents\CmsPhonenumber");
+        $class = $this->dm->getClassMetadata('Documents\CmsPhonenumber');
         $persister = $this->getMockDocumentPersister($pb, $class);
         $this->uow->setDocumentPersister('Documents\CmsPhonenumber', $persister);
 
-        $ph = new \Documents\CmsPhonenumber();
+        $ph = new CmsPhonenumber();
         $ph->phonenumber = '12345';
 
         $this->assertEquals(UnitOfWork::STATE_NEW, $this->uow->getDocumentState($ph));
@@ -254,10 +269,10 @@ public function testGetDocumentStateWithAssignedIdentity()
         $persister->reset();
 
         // if the document is already managed the exists() check should be skipped
-        $this->uow->registerManaged($ph, '12345', array());
+        $this->uow->registerManaged($ph, '12345', []);
         $this->assertEquals(UnitOfWork::STATE_MANAGED, $this->uow->getDocumentState($ph));
         $this->assertFalse($persister->isExistsCalled());
-        $ph2 = new \Documents\CmsPhonenumber();
+        $ph2 = new CmsPhonenumber();
         $ph2->phonenumber = '12345';
         $this->assertEquals(UnitOfWork::STATE_DETACHED, $this->uow->getDocumentState($ph2));
         $this->assertFalse($persister->isExistsCalled());
@@ -271,7 +286,7 @@ public function testThrowsOnPersistOfMappedSuperclass()
         $documentManager = $this->getDocumentManager();
         $documentManager->setClassMetadata('Documents\Address', $this->getClassMetadata('Documents\Address', 'MappedSuperclass'));
         $unitOfWork = $this->getUnitOfWork($documentManager);
-        $unitOfWork->persist(new \Documents\Address());
+        $unitOfWork->persist(new Address());
     }
 
     public function testParentAssociations()
@@ -283,11 +298,11 @@ public function testParentAssociations()
 
         $documentManager = $this->getDocumentManager();
         $unitOfWork = $this->getUnitOfWork($documentManager);
-        $unitOfWork->setParentAssociation($b, array('name' => 'b'), $a, 'b');
-        $unitOfWork->setParentAssociation($c, array('name' => 'c'), $b, 'b.c');
-        $unitOfWork->setParentAssociation($d, array('name' => 'd'), $c, 'b.c.d');
+        $unitOfWork->setParentAssociation($b, ['name' => 'b'], $a, 'b');
+        $unitOfWork->setParentAssociation($c, ['name' => 'c'], $b, 'b.c');
+        $unitOfWork->setParentAssociation($d, ['name' => 'd'], $c, 'b.c.d');
 
-        $this->assertEquals(array(array('name' => 'd'), $c, 'b.c.d'), $unitOfWork->getParentAssociation($d));
+        $this->assertEquals([['name' => 'd'], $c, 'b.c.d'], $unitOfWork->getParentAssociation($d));
     }
 
     /**
@@ -296,9 +311,9 @@ public function testParentAssociations()
     public function testPreUpdateTriggeredWithEmptyChangeset()
     {
         $this->dm->getEventManager()->addEventSubscriber(
-            new \Doctrine\ODM\MongoDB\Tests\Mocks\PreUpdateListenerMock()
+            new PreUpdateListenerMock()
         );
-        $user = new \Documents\ForumUser();
+        $user = new ForumUser();
         $user->username = '12345';
 
         $this->dm->persist($user);
@@ -311,7 +326,7 @@ public function testPreUpdateTriggeredWithEmptyChangeset()
 
     public function testNotSaved()
     {
-        $test = new \Documents\Functional\NotSaved();
+        $test = new NotSaved();
         $test->name = 'test';
         $test->notSaved = 'Jon';
         $this->dm->persist($test);
@@ -327,7 +342,7 @@ public function testNotSaved()
     public function testScheduleForUpdateWithArrays($origData, $updateData, $shouldInUpdate)
     {
         $pb = $this->getMockPersistenceBuilder();
-        $class = $this->dm->getClassMetadata("Doctrine\ODM\MongoDB\Tests\ArrayTest");
+        $class = $this->dm->getClassMetadata('Doctrine\ODM\MongoDB\Tests\ArrayTest');
         $persister = $this->getMockDocumentPersister($pb, $class);
         $this->uow->setDocumentPersister('Doctrine\ODM\MongoDB\Tests\ArrayTest', $persister);
 
@@ -348,53 +363,53 @@ public function testScheduleForUpdateWithArrays($origData, $updateData, $shouldI
 
     public function getScheduleForUpdateWithArraysTests()
     {
-        return array(
-            array(
+        return [
+            [
                 null,
-                array('bar' => 'foo'),
-                true
-            ),
-            array(
-                array('foo' => 'bar'),
+                ['bar' => 'foo'],
+                true,
+            ],
+            [
+                ['foo' => 'bar'],
                 null,
-                true
-            ),
-            array(
-                array('foo' => 'bar'),
-                array('bar' => 'foo'),
-                true
-            ),
-            array(
-                array('foo' => 'bar'),
-                array('foo' => 'foo'),
-                true
-            ),
-            array(
-                array('foo' => 'bar'),
-                array('foo' => 'bar'),
-                false
-            ),
-            array(
-                array('foo' => 'bar'),
-                array('foo' => true),
-                true
-            ),
-            array(
-                array('foo' => 'bar'),
-                array('foo' => 99),
-                true
-            ),
-            array(
-                array('foo' => 99),
-                array('foo' => true),
-                true
-            ),
-            array(
-                array('foo' => true),
-                array('foo' => true),
-                false
-            ),
-        );
+                true,
+            ],
+            [
+                ['foo' => 'bar'],
+                ['bar' => 'foo'],
+                true,
+            ],
+            [
+                ['foo' => 'bar'],
+                ['foo' => 'foo'],
+                true,
+            ],
+            [
+                ['foo' => 'bar'],
+                ['foo' => 'bar'],
+                false,
+            ],
+            [
+                ['foo' => 'bar'],
+                ['foo' => true],
+                true,
+            ],
+            [
+                ['foo' => 'bar'],
+                ['foo' => 99],
+                true,
+            ],
+            [
+                ['foo' => 99],
+                ['foo' => true],
+                true,
+            ],
+            [
+                ['foo' => true],
+                ['foo' => true],
+                false,
+            ],
+        ];
     }
 
     public function testRegisterManagedEmbeddedDocumentWithMappedIdAndNullValue()
@@ -402,7 +417,7 @@ public function testRegisterManagedEmbeddedDocumentWithMappedIdAndNullValue()
         $document = new EmbeddedDocumentWithId();
         $oid = spl_object_hash($document);
 
-        $this->uow->registerManaged($document, null, array());
+        $this->uow->registerManaged($document, null, []);
 
         $this->assertEquals($oid, $this->uow->getDocumentIdentifier($document));
     }
@@ -412,7 +427,7 @@ public function testRegisterManagedEmbeddedDocumentWithoutMappedId()
         $document = new EmbeddedDocumentWithoutId();
         $oid = spl_object_hash($document);
 
-        $this->uow->registerManaged($document, null, array());
+        $this->uow->registerManaged($document, null, []);
 
         $this->assertEquals($oid, $this->uow->getDocumentIdentifier($document));
     }
@@ -422,7 +437,7 @@ public function testRegisterManagedEmbeddedDocumentWithMappedIdStrategyNoneAndNu
         $document = new EmbeddedDocumentWithIdStrategyNone();
         $oid = spl_object_hash($document);
 
-        $this->uow->registerManaged($document, null, array());
+        $this->uow->registerManaged($document, null, []);
 
         $this->assertEquals($oid, $this->uow->getDocumentIdentifier($document));
     }
@@ -492,8 +507,8 @@ public function testPersistRemovedEmbeddedDocument()
 
     public function testPersistingEmbeddedDocumentWithoutIdentifier()
     {
-        $address = new \Documents\Address();
-        $user = new \Documents\User();
+        $address = new Address();
+        $user = new User();
         $user->setAddress($address);
 
         $this->assertEquals(UnitOfWork::STATE_NEW, $this->uow->getDocumentState($address));
@@ -515,8 +530,8 @@ public function testPersistingEmbeddedDocumentWithoutIdentifier()
 
     public function testEmbeddedDocumentChangeSets()
     {
-        $address = new \Documents\Address();
-        $user = new \Documents\User();
+        $address = new Address();
+        $user = new User();
         $user->setAddress($address);
 
         $this->uow->persist($user);
@@ -539,16 +554,12 @@ public function testEmbeddedDocumentChangeSets()
 
     public function testGetClassNameForAssociation()
     {
-        $mapping = array(
+        $mapping = [
             'discriminatorField' => 'type',
-            'discriminatorMap' => array(
-                'forum_user' => 'Documents\ForumUser',
-            ),
+            'discriminatorMap' => ['forum_user' => 'Documents\ForumUser'],
             'targetDocument' => 'Documents\User',
-        );
-        $data = array(
-            'type' => 'forum_user',
-        );
+        ];
+        $data = ['type' => 'forum_user'];
 
         $this->assertEquals('Documents\ForumUser', $this->uow->getClassNameForAssociation($mapping, $data));
     }
@@ -558,18 +569,12 @@ public function testGetClassNameForAssociationWithClassMetadataDiscriminatorMap(
         $dm = $this->getMockDocumentManager();
         $uow = new UnitOfWork($dm, $this->getMockEventManager(), $this->getMockHydratorFactory());
 
-        $mapping = array(
-            'targetDocument' => 'Documents\User',
-        );
-        $data = array(
-            'type' => 'forum_user',
-        );
+        $mapping = ['targetDocument' => 'Documents\User'];
+        $data = ['type' => 'forum_user'];
 
         $userClassMetadata = new ClassMetadata('Documents\ForumUser');
         $userClassMetadata->discriminatorField = 'type';
-        $userClassMetadata->discriminatorMap = array(
-            'forum_user' => 'Documents\ForumUser',
-        );
+        $userClassMetadata->discriminatorMap = ['forum_user' => 'Documents\ForumUser'];
 
         $dm->expects($this->once())
             ->method('getClassMetadata')
@@ -581,17 +586,15 @@ public function testGetClassNameForAssociationWithClassMetadataDiscriminatorMap(
 
     public function testGetClassNameForAssociationReturnsTargetDocumentWithNullData()
     {
-        $mapping = array(
-            'targetDocument' => 'Documents\User',
-        );
+        $mapping = ['targetDocument' => 'Documents\User'];
         $this->assertEquals('Documents\User', $this->uow->getClassNameForAssociation($mapping, null));
     }
 
     public function testRecomputeChangesetForUninitializedProxyDoesNotCreateChangeset()
     {
-        $user = new \Documents\ForumUser();
+        $user = new ForumUser();
         $user->username = '12345';
-        $user->setAvatar(new \Documents\ForumAvatar());
+        $user->setAvatar(new ForumAvatar());
 
         $this->dm->persist($user);
         $this->dm->flush();
@@ -608,20 +611,20 @@ public function testRecomputeChangesetForUninitializedProxyDoesNotCreateChangese
 
         $this->uow->recomputeSingleDocumentChangeSet($classMetadata, $user->getAvatar());
 
-        $this->assertEquals(array(), $this->uow->getDocumentChangeSet($user->getAvatar()));
+        $this->assertEquals([], $this->uow->getDocumentChangeSet($user->getAvatar()));
     }
 
     public function testCommitsInProgressIsUpdatedOnException()
     {
         $this->dm->getEventManager()->addEventSubscriber(
-            new \Doctrine\ODM\MongoDB\Tests\Mocks\ExceptionThrowingListenerMock()
+            new ExceptionThrowingListenerMock()
         );
-        $user = new \Documents\ForumUser();
+        $user = new ForumUser();
         $user->username = '12345';
 
         $this->dm->persist($user);
 
-        $this->expectException(\Exception::class);
+        $this->expectException(\Throwable::class);
         $this->expectExceptionMessage('This should not happen');
 
         $this->dm->flush();
@@ -642,7 +645,7 @@ protected function getUnitOfWork(DocumentManager $dm)
     /**
      * Gets mock HydratorFactory instance
      *
-     * @return \Doctrine\ODM\MongoDB\Hydrator\HydratorFactory
+     * @return HydratorFactory
      */
     private function getMockHydratorFactory()
     {
@@ -652,7 +655,7 @@ private function getMockHydratorFactory()
     /**
      * Gets mock EventManager instance
      *
-     * @return \Doctrine\Common\EventManager
+     * @return EventManager
      */
     private function getMockEventManager()
     {
@@ -696,9 +699,9 @@ public function __construct($name)
  * @ODM\Document
  * @ODM\ChangeTrackingPolicy("NOTIFY")
  */
-class NotifyChangedDocument implements \Doctrine\Common\NotifyPropertyChanged
+class NotifyChangedDocument implements NotifyPropertyChanged
 {
-    private $_listeners = array();
+    private $_listeners = [];
 
     /** @ODM\Id(type="int_id", strategy="none") */
     private $id;
@@ -711,7 +714,7 @@ class NotifyChangedDocument implements \Doctrine\Common\NotifyPropertyChanged
 
     private $transient; // not persisted
 
-    public function  __construct()
+    public function __construct()
     {
         $this->items = new ArrayCollection();
     }
@@ -733,7 +736,7 @@ public function getData()
 
     public function setData($data)
     {
-        if ($data != $this->data) {
+        if ($data !== $this->data) {
             $this->_onPropertyChanged('data', $this->data, $data);
             $this->data = $data;
         }
@@ -746,7 +749,7 @@ public function getItems()
 
     public function setTransient($value)
     {
-        if ($value != $this->transient) {
+        if ($value !== $this->transient) {
             $this->_onPropertyChanged('transient', $this->transient, $value);
             $this->transient = $value;
         }
diff --git a/tests/Documents/Account.php b/tests/Documents/Account.php
index 76da9a02db..2229b1218d 100644
--- a/tests/Documents/Account.php
+++ b/tests/Documents/Account.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Address.php b/tests/Documents/Address.php
index 9a98cb546b..656bab8127 100644
--- a/tests/Documents/Address.php
+++ b/tests/Documents/Address.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Agent.php b/tests/Documents/Agent.php
index 478ca6a447..136c6a730b 100644
--- a/tests/Documents/Agent.php
+++ b/tests/Documents/Agent.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -17,4 +19,4 @@ class Agent
      * })
      */
     public $server;
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Album.php b/tests/Documents/Album.php
index 205559fe68..b251094a6b 100644
--- a/tests/Documents/Album.php
+++ b/tests/Documents/Album.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -14,7 +16,7 @@ class Album
     private $name;
 
     /** @ODM\EmbedMany(targetDocument="Song") */
-    private $songs = array();
+    private $songs = [];
 
     public function __construct($name)
     {
diff --git a/tests/Documents/Article.php b/tests/Documents/Article.php
index 7ca4317125..0f551d1964 100644
--- a/tests/Documents/Article.php
+++ b/tests/Documents/Article.php
@@ -1,8 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function array_search;
+use function in_array;
 
 /**
  * @ODM\Document(collection="articles")
@@ -22,7 +26,7 @@ class Article
     private $createdAt;
 
     /** @ODM\Field(type="collection") */
-    private $tags = array();
+    private $tags = [];
 
     public function getId()
     {
@@ -66,8 +70,7 @@ public function addTag($tag)
 
     public function removeTag($tag)
     {
-        if ( ! in_array($tag, $this->tags))
-        {
+        if (! in_array($tag, $this->tags)) {
             return;
         }
         unset($this->tags[array_search($tag, $this->tags)]);
diff --git a/tests/Documents/Bars/Bar.php b/tests/Documents/Bars/Bar.php
index 4ca0753eb2..a173f8f333 100644
--- a/tests/Documents/Bars/Bar.php
+++ b/tests/Documents/Bars/Bar.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Bars;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -14,7 +16,7 @@ class Bar
     private $name;
 
     /** @ODM\EmbedMany(targetDocument="Documents\Bars\Location") */
-    private $locations = array();
+    private $locations = [];
 
     public function __construct($name = null)
     {
@@ -45,7 +47,7 @@ public function getLocations()
     {
         return $this->locations;
     }
-    
+
     public function setLocations($locations)
     {
         $this->locations = $locations;
diff --git a/tests/Documents/Bars/Location.php b/tests/Documents/Bars/Location.php
index b561bfeca8..292b5133c1 100644
--- a/tests/Documents/Bars/Location.php
+++ b/tests/Documents/Bars/Location.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Bars;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/BaseCategory.php b/tests/Documents/BaseCategory.php
index 64b31928dc..e170f4a566 100644
--- a/tests/Documents/BaseCategory.php
+++ b/tests/Documents/BaseCategory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -8,38 +10,38 @@
 abstract class BaseCategory
 {
     /** @ODM\Field(type="string") */
-     protected $name;
+    protected $name;
 
      /** @ODM\EmbedMany(targetDocument="SubCategory") */
-     protected $children = array();
-
-     public function __construct($name = null)
-     {
-         $this->name = $name;
-     }
-    
-     public function getId()
-     {
-         return $this->id;
-     }
-
-     public function setName($name)
-     {
-         $this->name = $name;
-     }
-
-     public function getName()
-     {
-         return $this->name;
-     }
-
-     public function addChild(BaseCategory $child)
-     {
-         $this->children[] = $child;
-     }
-
-     public function getChildren()
-     {
-         return $this->children;
-     }
+    protected $children = [];
+
+    public function __construct($name = null)
+    {
+        $this->name = $name;
+    }
+
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    public function addChild(BaseCategory $child)
+    {
+        $this->children[] = $child;
+    }
+
+    public function getChildren()
+    {
+        return $this->children;
+    }
 }
diff --git a/tests/Documents/BaseCategoryRepository.php b/tests/Documents/BaseCategoryRepository.php
index 3522b847ae..67a8e8e699 100644
--- a/tests/Documents/BaseCategoryRepository.php
+++ b/tests/Documents/BaseCategoryRepository.php
@@ -1,7 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
 
-class BaseCategoryRepository extends DocumentRepository {}
\ No newline at end of file
+class BaseCategoryRepository extends DocumentRepository
+{
+}
diff --git a/tests/Documents/BaseDocument.php b/tests/Documents/BaseDocument.php
index 5bde97032c..e2583e5781 100644
--- a/tests/Documents/BaseDocument.php
+++ b/tests/Documents/BaseDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/BaseEmployee.php b/tests/Documents/BaseEmployee.php
index ca2f8a4396..0a89272d4f 100644
--- a/tests/Documents/BaseEmployee.php
+++ b/tests/Documents/BaseEmployee.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -14,7 +16,7 @@ abstract class BaseEmployee
     protected $changes = 0;
 
     /** @ODM\Field(type="collection") */
-    protected $notes = array();
+    protected $notes = [];
 
     /** @ODM\Field(type="string") */
     protected $name;
diff --git a/tests/Documents/BlogPost.php b/tests/Documents/BlogPost.php
index 9133b14c1e..9eb6b41891 100644
--- a/tests/Documents/BlogPost.php
+++ b/tests/Documents/BlogPost.php
@@ -1,9 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
-use Documents\User;
 
 /** @ODM\Document */
 class BlogPost
@@ -15,10 +16,10 @@ class BlogPost
     public $name;
 
     /** @ODM\ReferenceMany(targetDocument="Tag", inversedBy="blogPosts", cascade={"all"}) */
-    public $tags = array();
+    public $tags = [];
 
     /** @ODM\ReferenceMany(targetDocument="Comment", mappedBy="parent", cascade={"all"}, prime={"author"}) */
-    public $comments = array();
+    public $comments = [];
 
     /** @ODM\ReferenceOne(targetDocument="Comment", mappedBy="parent", sort={"date"="asc"}) */
     public $firstComment;
@@ -27,10 +28,10 @@ class BlogPost
     public $latestComment;
 
     /** @ODM\ReferenceMany(targetDocument="Comment", mappedBy="parent", sort={"date"="desc"}, limit=5) */
-    public $last5Comments = array();
+    public $last5Comments = [];
 
     /** @ODM\ReferenceMany(targetDocument="Comment", mappedBy="parent", criteria={"isByAdmin"=true}, sort={"date"="desc"}) */
-    public $adminComments = array();
+    public $adminComments = [];
 
     /** @ODM\ReferenceOne(targetDocument="Comment", mappedBy="parent", repositoryMethod="findOneComment") */
     public $repoComment;
@@ -75,7 +76,7 @@ public function addComment(Comment $comment)
         $this->comments[] = $comment;
     }
 
-    public function setUser(User $user = null)
+    public function setUser(?User $user = null)
     {
         $this->user = $user;
     }
diff --git a/tests/Documents/BlogTagAggregation.php b/tests/Documents/BlogTagAggregation.php
index 8c715ac5f6..b4edfcdbeb 100644
--- a/tests/Documents/BlogTagAggregation.php
+++ b/tests/Documents/BlogTagAggregation.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Book.php b/tests/Documents/Book.php
index 55d6a65076..0aff645325 100644
--- a/tests/Documents/Book.php
+++ b/tests/Documents/Book.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -8,7 +10,7 @@
 /** @ODM\Document */
 class Book
 {
-    const CLASSNAME = __CLASS__;
+    public const CLASSNAME = __CLASS__;
 
     /** @ODM\Id */
     public $id;
diff --git a/tests/Documents/BrowseNode.php b/tests/Documents/BrowseNode.php
index 6b0e303c94..4d4e6701a5 100644
--- a/tests/Documents/BrowseNode.php
+++ b/tests/Documents/BrowseNode.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\Document */
@@ -26,7 +29,7 @@ class BrowseNode
     public function __construct($name = null)
     {
         $this->name = $name;
-        $this->children = new \Doctrine\Common\Collections\ArrayCollection();
+        $this->children = new ArrayCollection();
     }
 
     public function addChild(BrowseNode $child)
diff --git a/tests/Documents/Cart.php b/tests/Documents/Cart.php
index 1ef1d6ea88..68502569a8 100644
--- a/tests/Documents/Cart.php
+++ b/tests/Documents/Cart.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Category.php b/tests/Documents/Category.php
index 967cce1f49..7bebf309e7 100644
--- a/tests/Documents/Category.php
+++ b/tests/Documents/Category.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -9,4 +11,4 @@ class Category extends BaseCategory
 {
     /** @ODM\Id */
     private $id;
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Chapter.php b/tests/Documents/Chapter.php
index 771c27bff6..194361f11f 100644
--- a/tests/Documents/Chapter.php
+++ b/tests/Documents/Chapter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Documents/CmsAddress.php b/tests/Documents/CmsAddress.php
index efe5eaa25e..65b7cffbae 100644
--- a/tests/Documents/CmsAddress.php
+++ b/tests/Documents/CmsAddress.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -37,27 +39,33 @@ class CmsAddress
      */
     public $user;
 
-    public function getId() {
+    public function getId()
+    {
         return $this->id;
     }
-    
-    public function getUser() {
+
+    public function getUser()
+    {
         return $this->user;
     }
 
-    public function getCountry() {
+    public function getCountry()
+    {
         return $this->country;
     }
 
-    public function getZipCode() {
+    public function getZipCode()
+    {
         return $this->zip;
     }
 
-    public function getCity() {
+    public function getCity()
+    {
         return $this->city;
     }
-    
-    public function setUser(CmsUser $user) {
+
+    public function setUser(CmsUser $user)
+    {
         if ($this->user !== $user) {
             $this->user = $user;
             $user->setAddress($this);
diff --git a/tests/Documents/CmsArticle.php b/tests/Documents/CmsArticle.php
index e96f37f299..9567ff3165 100644
--- a/tests/Documents/CmsArticle.php
+++ b/tests/Documents/CmsArticle.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -33,11 +35,13 @@ class CmsArticle
      */
     public $comments;
 
-    public function setAuthor(CmsUser $author) {
+    public function setAuthor(CmsUser $author)
+    {
         $this->user = $author;
     }
 
-    public function addComment(CmsComment $comment) {
+    public function addComment(CmsComment $comment)
+    {
         $this->comments[] = $comment;
         $comment->setArticle($this);
     }
diff --git a/tests/Documents/CmsComment.php b/tests/Documents/CmsComment.php
index ad7bde8d5b..72498abcf9 100644
--- a/tests/Documents/CmsComment.php
+++ b/tests/Documents/CmsComment.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -32,11 +34,13 @@ class CmsComment
     /** @ODM\Field(name="ip", type="string") */
     public $authorIp;
 
-    public function setArticle(CmsArticle $article) {
+    public function setArticle(CmsArticle $article)
+    {
         $this->article = $article;
     }
 
-    public function __toString() {
-        return __CLASS__."[id=".$this->id."]";
+    public function __toString()
+    {
+        return __CLASS__ . '[id=' . $this->id . ']';
     }
 }
diff --git a/tests/Documents/CmsContent.php b/tests/Documents/CmsContent.php
index 5bc758b772..2038beddd8 100644
--- a/tests/Documents/CmsContent.php
+++ b/tests/Documents/CmsContent.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/CmsGroup.php b/tests/Documents/CmsGroup.php
index b3d2857979..240390ceab 100644
--- a/tests/Documents/CmsGroup.php
+++ b/tests/Documents/CmsGroup.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -22,19 +24,23 @@ class CmsGroup
      */
     public $users;
 
-    public function setName($name) {
+    public function setName($name)
+    {
         $this->name = $name;
     }
 
-    public function getName() {
+    public function getName()
+    {
         return $this->name;
     }
 
-    public function addUser(CmsUser $user) {
+    public function addUser(CmsUser $user)
+    {
         $this->users[] = $user;
     }
 
-    public function getUsers() {
+    public function getUsers()
+    {
         return $this->users;
     }
 }
diff --git a/tests/Documents/CmsPage.php b/tests/Documents/CmsPage.php
index 6948b5c1e2..37bf95356c 100644
--- a/tests/Documents/CmsPage.php
+++ b/tests/Documents/CmsPage.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/CmsPhonenumber.php b/tests/Documents/CmsPhonenumber.php
index f06217038b..8176c4eea7 100644
--- a/tests/Documents/CmsPhonenumber.php
+++ b/tests/Documents/CmsPhonenumber.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -17,11 +19,13 @@ class CmsPhonenumber
      */
     public $user;
 
-    public function setUser(CmsUser $user) {
+    public function setUser(CmsUser $user)
+    {
         $this->user = $user;
     }
-    
-    public function getUser() {
+
+    public function getUser()
+    {
         return $this->user;
     }
 }
diff --git a/tests/Documents/CmsProduct.php b/tests/Documents/CmsProduct.php
index 828dbc5813..8e32c66d27 100644
--- a/tests/Documents/CmsProduct.php
+++ b/tests/Documents/CmsProduct.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/CmsUser.php b/tests/Documents/CmsUser.php
index 040af22826..c2c8740a58 100644
--- a/tests/Documents/CmsUser.php
+++ b/tests/Documents/CmsUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -49,58 +51,68 @@ class CmsUser
      * @ODM\ReferenceMany(targetDocument="CmsGroup", cascade={"persist", "merge"})
      */
     public $groups;
-    
-    public function __construct() {
-        $this->phonenumbers = new ArrayCollection;
-        $this->articles = new ArrayCollection;
-        $this->groups = new ArrayCollection;
+
+    public function __construct()
+    {
+        $this->phonenumbers = new ArrayCollection();
+        $this->articles = new ArrayCollection();
+        $this->groups = new ArrayCollection();
     }
 
-    public function getId() {
+    public function getId()
+    {
         return $this->id;
     }
 
-    public function getStatus() {
+    public function getStatus()
+    {
         return $this->status;
     }
 
-    public function getUsername() {
+    public function getUsername()
+    {
         return $this->username;
     }
 
-    public function getName() {
+    public function getName()
+    {
         return $this->name;
     }
 
     /**
      * Adds a phonenumber to the user.
      *
-     * @param CmsPhonenumber $phone
      */
-    public function addPhonenumber(CmsPhonenumber $phone) {
+    public function addPhonenumber(CmsPhonenumber $phone)
+    {
         $this->phonenumbers[] = $phone;
         $phone->setUser($this);
     }
 
-    public function getPhonenumbers() {
+    public function getPhonenumbers()
+    {
         return $this->phonenumbers;
     }
 
-    public function addArticle(CmsArticle $article) {
+    public function addArticle(CmsArticle $article)
+    {
         $this->articles[] = $article;
         $article->setAuthor($this);
     }
 
-    public function addGroup(CmsGroup $group) {
+    public function addGroup(CmsGroup $group)
+    {
         $this->groups[] = $group;
         $group->addUser($this);
     }
 
-    public function getGroups() {
+    public function getGroups()
+    {
         return $this->groups;
     }
 
-    public function removePhonenumber($index) {
+    public function removePhonenumber($index)
+    {
         if (isset($this->phonenumbers[$index])) {
             $ph = $this->phonenumbers[$index];
             unset($this->phonenumbers[$index]);
@@ -109,10 +121,14 @@ public function removePhonenumber($index) {
         }
         return false;
     }
-    
-    public function getAddress() { return $this->address; }
-    
-    public function setAddress(CmsAddress $address) {
+
+    public function getAddress()
+    {
+        return $this->address;
+    }
+
+    public function setAddress(CmsAddress $address)
+    {
         if ($this->address !== $address) {
             $this->address = $address;
             $address->setUser($this);
diff --git a/tests/Documents/Comment.php b/tests/Documents/Comment.php
index 72efbf2155..e241777331 100644
--- a/tests/Documents/Comment.php
+++ b/tests/Documents/Comment.php
@@ -1,9 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use DateTime;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\Document(repositoryClass="Documents\CommentRepository") */
 class Comment
@@ -37,5 +39,4 @@ public function getText()
     {
         return $this->text;
     }
-
 }
diff --git a/tests/Documents/CommentRepository.php b/tests/Documents/CommentRepository.php
index 57c776c061..0c8f98c75f 100644
--- a/tests/Documents/CommentRepository.php
+++ b/tests/Documents/CommentRepository.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
diff --git a/tests/Documents/CustomRepository/Document.php b/tests/Documents/CustomRepository/Document.php
index bcf9fd0510..50416e0b36 100644
--- a/tests/Documents/CustomRepository/Document.php
+++ b/tests/Documents/CustomRepository/Document.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\CustomRepository;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -7,9 +9,10 @@
 /**
  * @ODM\Document(repositoryClass="Documents\CustomRepository\Repository")
  */
-class Document {
-	/**
-	 * @ODM\Id
-	 */
-	protected $id;
+class Document
+{
+    /**
+     * @ODM\Id
+     */
+    protected $id;
 }
diff --git a/tests/Documents/CustomRepository/Repository.php b/tests/Documents/CustomRepository/Repository.php
index de22bffa3d..5ad3723534 100644
--- a/tests/Documents/CustomRepository/Repository.php
+++ b/tests/Documents/CustomRepository/Repository.php
@@ -1,7 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\CustomRepository;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
 
-class Repository extends DocumentRepository {}
+class Repository extends DocumentRepository
+{
+}
diff --git a/tests/Documents/CustomUser.php b/tests/Documents/CustomUser.php
index 1289f2a1f8..89d5b0da02 100644
--- a/tests/Documents/CustomUser.php
+++ b/tests/Documents/CustomUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Customer.php b/tests/Documents/Customer.php
index ef11fb40b9..2a79204331 100644
--- a/tests/Documents/Customer.php
+++ b/tests/Documents/Customer.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Developer.php b/tests/Documents/Developer.php
index 3c129be052..58ed892e56 100644
--- a/tests/Documents/Developer.php
+++ b/tests/Documents/Developer.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -26,10 +28,10 @@ class Developer
      */
     private $projects;
 
-    public function __construct($name, Collection $projects = null)
+    public function __construct($name, ?Collection $projects = null)
     {
         $this->name = $name;
-        $this->projects = null === $projects ? new ArrayCollection() : $projects;
+        $this->projects = $projects === null ? new ArrayCollection() : $projects;
     }
 
     public function getId()
diff --git a/tests/Documents/Ecommerce/ConfigurableProduct.php b/tests/Documents/Ecommerce/ConfigurableProduct.php
index 874d22a57d..b898152287 100644
--- a/tests/Documents/Ecommerce/ConfigurableProduct.php
+++ b/tests/Documents/Ecommerce/ConfigurableProduct.php
@@ -1,8 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Ecommerce;
 
+use Doctrine\Common\Collections\Collection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function array_map;
+use function array_search;
+use function in_array;
 
 /**
  * @ODM\Document
@@ -22,14 +28,14 @@ class ConfigurableProduct
     /**
      * @ODM\EmbedMany(targetDocument="Documents\Ecommerce\Option")
      */
-    protected $options = array();
+    protected $options = [];
 
     /**
      * @var Documents\Option
      */
     protected $selectedOption;
 
-    public function  __construct($name)
+    public function __construct($name)
     {
         $this->setName($name);
     }
@@ -61,12 +67,11 @@ public function getOptions()
 
     /**
      * @param string|Option $name
-     * @param float|null $price
-     * @param StockItem|null $item
+     * @param float|null    $price
      */
-    public function addOption($name, $price = null, StockItem $item = null)
+    public function addOption($name, $price = null, ?StockItem $item = null)
     {
-        if ( ! $name instanceof Option) {
+        if (! $name instanceof Option) {
             $name = (string) $name;
             if (empty($name)) {
                 throw new \InvalidArgumentException('option name cannot be empty');
@@ -74,7 +79,7 @@ public function addOption($name, $price = null, StockItem $item = null)
             $name = new Option($name, $price, $item);
             unset($price, $item);
         }
-        if (null !== $this->_findOption($name->getName())
+        if ($this->_findOption($name->getName()) !== null
             || in_array($name->getStockItem(), $this->_getStockItems(), true)) {
             throw new \InvalidArgumentException('cannot add option with the same name twice');
         }
@@ -88,10 +93,10 @@ public function getOption($name)
 
     public function removeOption($name)
     {
-        if(null === ($option = $this->_findOption($name))) {
+        if (($option = $this->_findOption($name)) === null) {
             throw new \InvalidArgumentException('option ' . $name . ' doesn\'t exist');
         }
-        if ($this->options instanceof \Doctrine\Common\Collections\Collection) {
+        if ($this->options instanceof Collection) {
             $index = $this->options->indexOf($option);
         } else {
             $index = array_search($option, $this->options);
@@ -102,13 +107,13 @@ public function removeOption($name)
 
     public function hasOption($name)
     {
-        return null !== $this->_findOption($name);
+        return $this->_findOption($name) !== null;
     }
 
     public function selectOption($name)
     {
         $option = $this->_findOption($name);
-        if ( ! isset($option)) {
+        if (! isset($option)) {
             throw new \InvalidArgumentException('specified option: ' . $name . ' doesn\'t exist');
         }
         $this->selectedOption = $option;
@@ -118,7 +123,7 @@ public function selectOption($name)
     protected function _findOption($name)
     {
         foreach ($this->options as $option) {
-            if ($name == $option->getName()) {
+            if ($name === $option->getName()) {
                 return $option;
             }
         }
@@ -137,5 +142,4 @@ protected function _getStockItems()
             return $option->getStockItem();
         }, $this->getOptions());
     }
-
 }
diff --git a/tests/Documents/Ecommerce/Currency.php b/tests/Documents/Ecommerce/Currency.php
index 5002c892e0..479eb1d201 100644
--- a/tests/Documents/Ecommerce/Currency.php
+++ b/tests/Documents/Ecommerce/Currency.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Ecommerce;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function implode;
+use function in_array;
 
 /**
  * @ODM\Document
  */
 class Currency
 {
-    const
+    public const
         USD   = 'USD',
         EURO  = 'EURO',
         JPN   = 'JPN';
@@ -32,7 +36,7 @@ class Currency
     public function __construct($name, $multiplier = 1)
     {
         $name = (string) $name;
-        if ( ! in_array($name, self::getAll())) {
+        if (! in_array($name, self::getAll())) {
             throw new \InvalidArgumentException(
                 'Currency must be one of ' . implode(', ', self::getAll()) .
                 $name . 'given'
@@ -70,10 +74,10 @@ public function setMultiplier($multiplier)
 
     public static function getAll()
     {
-        return array(
+        return [
             self::USD,
             self::EURO,
             self::JPN,
-        );
+        ];
     }
 }
diff --git a/tests/Documents/Ecommerce/Money.php b/tests/Documents/Ecommerce/Money.php
index be231be6c1..48fbc0690f 100644
--- a/tests/Documents/Ecommerce/Money.php
+++ b/tests/Documents/Ecommerce/Money.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Ecommerce;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Ecommerce/Option.php b/tests/Documents/Ecommerce/Option.php
index 874f364292..8c1c5d2b70 100644
--- a/tests/Documents/Ecommerce/Option.php
+++ b/tests/Documents/Ecommerce/Option.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Ecommerce;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -32,8 +34,7 @@ class Option
 
     /**
      * @param string $name
-     * @param float $price
-     * @param StockItem $stockItem
+     * @param float  $price
      */
     public function __construct($name, Money $money, StockItem $stockItem)
     {
@@ -61,7 +62,7 @@ public function getName()
      */
     public function getPrice($object = false)
     {
-        if (true === $object) {
+        if ($object === true) {
             return $this->money;
         }
         return $this->money->getAmount();
diff --git a/tests/Documents/Ecommerce/StockItem.php b/tests/Documents/Ecommerce/StockItem.php
index ffeed94f0b..7baf726c0e 100644
--- a/tests/Documents/Ecommerce/StockItem.php
+++ b/tests/Documents/Ecommerce/StockItem.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Ecommerce;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -34,15 +36,15 @@ public function getId()
         return $this->id;
     }
 
-    public function  __construct($name = null, $cost = null, $inventory = null)
+    public function __construct($name = null, $cost = null, $inventory = null)
     {
-        if (null !== $name) {
+        if ($name !== null) {
             $this->setName($name);
         }
-        if (null !== $cost) {
+        if ($cost !== null) {
             $this->setCost($cost);
         }
-        if (null !== $inventory) {
+        if ($inventory !== null) {
             $this->setInventory($inventory);
         }
     }
diff --git a/tests/Documents/Employee.php b/tests/Documents/Employee.php
index 69278c48cd..7c72500d63 100644
--- a/tests/Documents/Employee.php
+++ b/tests/Documents/Employee.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -20,4 +22,4 @@ public function setManager($val)
         $this->manager = $val;
         return $this;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Event.php b/tests/Documents/Event.php
index 452821761b..bc57dabb64 100644
--- a/tests/Documents/Event.php
+++ b/tests/Documents/Event.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Feature.php b/tests/Documents/Feature.php
index 0939dbb65c..e0093d396c 100644
--- a/tests/Documents/Feature.php
+++ b/tests/Documents/Feature.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/File.php b/tests/Documents/File.php
index ce4c1ea408..54d4cd5c11 100644
--- a/tests/Documents/File.php
+++ b/tests/Documents/File.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/ForumAvatar.php b/tests/Documents/ForumAvatar.php
index 7bd93ac43c..2f12d3e560 100644
--- a/tests/Documents/ForumAvatar.php
+++ b/tests/Documents/ForumAvatar.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/ForumUser.php b/tests/Documents/ForumUser.php
index ed81262d11..9d149f2f96 100644
--- a/tests/Documents/ForumUser.php
+++ b/tests/Documents/ForumUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -15,24 +17,24 @@ class ForumUser
 
     /** @ODM\ReferenceOne(targetDocument="ForumAvatar", cascade={"persist"}) */
     public $avatar;
-    
+
     public function getId()
     {
-    	return $this->id;
+        return $this->id;
     }
-    
+
     public function getUsername()
     {
-    	return $this->username;
+        return $this->username;
     }
-    
+
     public function getAvatar()
     {
-    	return $this->avatar;
+        return $this->avatar;
     }
-    
+
     public function setAvatar(ForumAvatar $avatar)
     {
-    	$this->avatar = $avatar;
+        $this->avatar = $avatar;
     }
 }
diff --git a/tests/Documents/FriendUser.php b/tests/Documents/FriendUser.php
index 1238f88cae..bb38237563 100644
--- a/tests/Documents/FriendUser.php
+++ b/tests/Documents/FriendUser.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\Document */
@@ -26,8 +29,8 @@ class FriendUser
     public function __construct($name)
     {
         $this->name = $name;
-        $this->friendsWithMe = new \Doctrine\Common\Collections\ArrayCollection();
-        $this->myFriends = new \Doctrine\Common\Collections\ArrayCollection();
+        $this->friendsWithMe = new ArrayCollection();
+        $this->myFriends = new ArrayCollection();
     }
 
     public function addFriend(FriendUser $user)
diff --git a/tests/Documents/Functional/EmbedNamed.php b/tests/Documents/Functional/EmbedNamed.php
index 6a30ccadb9..0da05f713f 100644
--- a/tests/Documents/Functional/EmbedNamed.php
+++ b/tests/Documents/Functional/EmbedNamed.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Embedded.php b/tests/Documents/Functional/Embedded.php
index a682f69fde..9c22a06e42 100644
--- a/tests/Documents/Functional/Embedded.php
+++ b/tests/Documents/Functional/Embedded.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/EmbeddedTestLevel0.php b/tests/Documents/Functional/EmbeddedTestLevel0.php
index a396449e8e..7ec2c3920d 100644
--- a/tests/Documents/Functional/EmbeddedTestLevel0.php
+++ b/tests/Documents/Functional/EmbeddedTestLevel0.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -12,5 +14,5 @@ class EmbeddedTestLevel0
     /** @ODM\Field(type="string") */
     public $name;
     /** @ODM\EmbedMany(targetDocument="EmbeddedTestLevel1") */
-    public $level1 = array();
+    public $level1 = [];
 }
diff --git a/tests/Documents/Functional/EmbeddedTestLevel0b.php b/tests/Documents/Functional/EmbeddedTestLevel0b.php
index 25044e0b36..b29d0cff0b 100644
--- a/tests/Documents/Functional/EmbeddedTestLevel0b.php
+++ b/tests/Documents/Functional/EmbeddedTestLevel0b.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -14,5 +16,5 @@ class EmbeddedTestLevel0b
     /** @ODM\EmbedOne(targetDocument="EmbeddedTestLevel1") */
     public $oneLevel1;
     /** @ODM\EmbedMany(targetDocument="EmbeddedTestLevel1") */
-    public $level1 = array();
+    public $level1 = [];
 }
diff --git a/tests/Documents/Functional/EmbeddedTestLevel1.php b/tests/Documents/Functional/EmbeddedTestLevel1.php
index 1352312bb5..06338b6d82 100644
--- a/tests/Documents/Functional/EmbeddedTestLevel1.php
+++ b/tests/Documents/Functional/EmbeddedTestLevel1.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -10,7 +12,7 @@ class EmbeddedTestLevel1
     /** @ODM\Field(type="string") */
     public $name;
     /** @ODM\EmbedMany(targetDocument="EmbeddedTestLevel2") */
-    public $level2 = array();
+    public $level2 = [];
 
     public $preRemove = false;
     public $postRemove = false;
diff --git a/tests/Documents/Functional/EmbeddedTestLevel2.php b/tests/Documents/Functional/EmbeddedTestLevel2.php
index a6b705f444..0788d37763 100644
--- a/tests/Documents/Functional/EmbeddedTestLevel2.php
+++ b/tests/Documents/Functional/EmbeddedTestLevel2.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/EmbeddedWhichReferences.php b/tests/Documents/Functional/EmbeddedWhichReferences.php
index 872c8c1e36..54763b66ef 100644
--- a/tests/Documents/Functional/EmbeddedWhichReferences.php
+++ b/tests/Documents/Functional/EmbeddedWhichReferences.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/FavoritesUser.php b/tests/Documents/Functional/FavoritesUser.php
index 558cacaa22..54617cfbca 100644
--- a/tests/Documents/Functional/FavoritesUser.php
+++ b/tests/Documents/Functional/FavoritesUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -22,10 +24,10 @@ class FavoritesUser
      *   }
      * )
      */
-    private $favorites = array();
+    private $favorites = [];
 
     /** @ODM\EmbedMany */
-    private $embedded = array();
+    private $embedded = [];
 
     /** @ODM\ReferenceOne */
     private $favorite;
diff --git a/tests/Documents/Functional/NotAnnotatedDocument.php b/tests/Documents/Functional/NotAnnotatedDocument.php
index f5ad845545..85bee9ea9c 100644
--- a/tests/Documents/Functional/NotAnnotatedDocument.php
+++ b/tests/Documents/Functional/NotAnnotatedDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -14,4 +16,4 @@ class NotAnnotatedDocument
     public $field;
 
     public $transientField;
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Functional/NotSaved.php b/tests/Documents/Functional/NotSaved.php
index 24d60474c7..509069c329 100644
--- a/tests/Documents/Functional/NotSaved.php
+++ b/tests/Documents/Functional/NotSaved.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/NotSavedEmbedded.php b/tests/Documents/Functional/NotSavedEmbedded.php
index ff84e1bddd..2d9bf80421 100644
--- a/tests/Documents/Functional/NotSavedEmbedded.php
+++ b/tests/Documents/Functional/NotSavedEmbedded.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/NullFieldValues.php b/tests/Documents/Functional/NullFieldValues.php
index 34821c7640..085312ed39 100644
--- a/tests/Documents/Functional/NullFieldValues.php
+++ b/tests/Documents/Functional/NullFieldValues.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -12,4 +14,4 @@ class NullFieldValues
 
     /** @ODM\Field(nullable=true) */
     public $field;
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Functional/PreUpdateTestProduct.php b/tests/Documents/Functional/PreUpdateTestProduct.php
index 447120cae2..515be0b5bb 100644
--- a/tests/Documents/Functional/PreUpdateTestProduct.php
+++ b/tests/Documents/Functional/PreUpdateTestProduct.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/PreUpdateTestSellable.php b/tests/Documents/Functional/PreUpdateTestSellable.php
index f980aba5ec..a3ce97e98f 100644
--- a/tests/Documents/Functional/PreUpdateTestSellable.php
+++ b/tests/Documents/Functional/PreUpdateTestSellable.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -24,4 +26,4 @@ public function getSeller()
     {
         return $this->seller;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Functional/PreUpdateTestSeller.php b/tests/Documents/Functional/PreUpdateTestSeller.php
index 40b57e3ea6..2975455685 100644
--- a/tests/Documents/Functional/PreUpdateTestSeller.php
+++ b/tests/Documents/Functional/PreUpdateTestSeller.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Reference.php b/tests/Documents/Functional/Reference.php
index c0392a530a..50f1716468 100644
--- a/tests/Documents/Functional/Reference.php
+++ b/tests/Documents/Functional/Reference.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/SameCollection1.php b/tests/Documents/Functional/SameCollection1.php
index 247c5a928f..c1a9cc2dfb 100644
--- a/tests/Documents/Functional/SameCollection1.php
+++ b/tests/Documents/Functional/SameCollection1.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/SameCollection2.php b/tests/Documents/Functional/SameCollection2.php
index fa96d59997..6f1cebcf57 100644
--- a/tests/Documents/Functional/SameCollection2.php
+++ b/tests/Documents/Functional/SameCollection2.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/SameCollection3.php b/tests/Documents/Functional/SameCollection3.php
index ab621e178f..0cc1f27fb5 100644
--- a/tests/Documents/Functional/SameCollection3.php
+++ b/tests/Documents/Functional/SameCollection3.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/SimpleEmbedAndReference.php b/tests/Documents/Functional/SimpleEmbedAndReference.php
index 5a7750240c..3aebc386df 100644
--- a/tests/Documents/Functional/SimpleEmbedAndReference.php
+++ b/tests/Documents/Functional/SimpleEmbedAndReference.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -11,14 +13,14 @@ class SimpleEmbedAndReference
     public $id;
 
     /** @ODM\EmbedMany(targetDocument="Embedded") */
-    public $embedMany = array();
+    public $embedMany = [];
 
     /** @ODM\ReferenceMany(targetDocument="Reference") */
-    public $referenceMany = array();
+    public $referenceMany = [];
 
     /** @ODM\EmbedOne(targetDocument="Embedded") */
     public $embedOne;
 
     /** @ODM\ReferenceOne(targetDocument="Reference") */
     public $referenceOne;
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Functional/Ticket/GH683/AbstractEmbedded.php b/tests/Documents/Functional/Ticket/GH683/AbstractEmbedded.php
index 4eb86f9aab..0f01717ceb 100644
--- a/tests/Documents/Functional/Ticket/GH683/AbstractEmbedded.php
+++ b/tests/Documents/Functional/Ticket/GH683/AbstractEmbedded.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\GH683;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument1.php b/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument1.php
index 1fa431c171..bd9c5c3ad4 100644
--- a/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument1.php
+++ b/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument1.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\GH683;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument2.php b/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument2.php
index 7b2c961db7..37433aeb54 100644
--- a/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument2.php
+++ b/tests/Documents/Functional/Ticket/GH683/EmbeddedSubDocument2.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\GH683;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/GH683/ParentDocument.php b/tests/Documents/Functional/Ticket/GH683/ParentDocument.php
index 87221ff677..9e8a963de4 100644
--- a/tests/Documents/Functional/Ticket/GH683/ParentDocument.php
+++ b/tests/Documents/Functional/Ticket/GH683/ParentDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\GH683;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel0.php b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel0.php
index 96452584d4..269fd4d9de 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel0.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel0.php
@@ -1,10 +1,11 @@
 <?php
 
-namespace Documents\Functional\Ticket\MODM160;
+declare(strict_types=1);
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\Document(collection="embedded_test") */
 class EmbedManyInArrayCollectionLevel0
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel1.php b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel1.php
index 4ec3e3d286..e376229309 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel1.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayCollectionLevel1.php
@@ -1,10 +1,11 @@
 <?php
 
-namespace Documents\Functional\Ticket\MODM160;
+declare(strict_types=1);
 
-use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\EmbeddedDocument */
 class EmbedManyInArrayCollectionLevel1
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel0.php b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel0.php
index 85065c44c3..a5592cb847 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel0.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel0.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -12,5 +14,5 @@ class EmbedManyInArrayLevel0
     /** @ODM\Field(type="string") */
     public $name;
     /** @ODM\EmbedMany(targetDocument="EmbedManyInArrayLevel1") */
-    public $level1 = array();
+    public $level1 = [];
 }
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel1.php b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel1.php
index 5016ef64d9..2b5707aa85 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel1.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedManyInArrayLevel1.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -10,5 +12,5 @@ class EmbedManyInArrayLevel1
     /** @ODM\Field(type="string") */
     public $name;
     /** @ODM\EmbedMany(targetDocument="MODM160Level2") */
-    public $level2 = array();
+    public $level2 = [];
 }
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel0.php b/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel0.php
index a1aea153f4..83052b1719 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel0.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel0.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel1.php b/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel1.php
index d6f599c14a..eb58ea8547 100644
--- a/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel1.php
+++ b/tests/Documents/Functional/Ticket/MODM160/EmbedOneLevel1.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Functional/Ticket/MODM160/MODM160Level2.php b/tests/Documents/Functional/Ticket/MODM160/MODM160Level2.php
index 4ed435ff83..3ef0c8c8dd 100644
--- a/tests/Documents/Functional/Ticket/MODM160/MODM160Level2.php
+++ b/tests/Documents/Functional/Ticket/MODM160/MODM160Level2.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional\Ticket\MODM160;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -9,6 +11,4 @@ class MODM160Level2
 {
     /** @ODM\Field(type="string") */
     public $name;
-
-
 }
diff --git a/tests/Documents/Functional/VirtualHost.php b/tests/Documents/Functional/VirtualHost.php
index 7362ac3145..582db9b4c2 100644
--- a/tests/Documents/Functional/VirtualHost.php
+++ b/tests/Documents/Functional/VirtualHost.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -9,7 +11,6 @@
  */
 class VirtualHost
 {
-
     /** @ODM\Id */
     protected $id;
     /**
@@ -27,7 +28,7 @@ public function getId()
      */
     public function getVHostDirective()
     {
-        if (!$this->vhostDirective) {
+        if (! $this->vhostDirective) {
             $this->vhostDirective = new VirtualHostDirective('VirtualHost', '*:80');
         }
         return $this->vhostDirective;
@@ -39,6 +40,4 @@ public function setVHostDirective($value)
 
         return $this;
     }
-
 }
-
diff --git a/tests/Documents/Functional/VirtualHostDirective.php b/tests/Documents/Functional/VirtualHostDirective.php
index 8bbefa7cd5..fc7f9b5036 100644
--- a/tests/Documents/Functional/VirtualHostDirective.php
+++ b/tests/Documents/Functional/VirtualHostDirective.php
@@ -1,8 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Functional;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function uniqid;
 
 /** @ODM\EmbeddedDocument */
 class VirtualHostDirective
@@ -19,7 +23,7 @@ class VirtualHostDirective
     protected $directives;
 
 
-    public function __construct($name='', $value='')
+    public function __construct($name = '', $value = '')
     {
         $this->name = $name;
         $this->value = $value;
@@ -35,10 +39,11 @@ public function getRecId()
         return $this->recId;
     }
 
-    public function setRecId($value=null)
+    public function setRecId($value = null)
     {
-        if (!$value)
+        if (! $value) {
             $value = uniqid();
+        }
 
         $this->recId = $value;
     }
@@ -67,8 +72,9 @@ public function setValue($value)
 
     public function getDirectives()
     {
-        if (!$this->directives)
-            $this->directives = new \Doctrine\Common\Collections\ArrayCollection(array());
+        if (! $this->directives) {
+            $this->directives = new ArrayCollection([]);
+        }
         return $this->directives;
     }
 
@@ -94,7 +100,7 @@ public function addDirective(VirtualHostDirective $d)
     public function hasDirective($name)
     {
         foreach ($this->getDirectives() as $d) {
-            if ($d->getName() == $name) {
+            if ($d->getName() === $name) {
                 return $d;
             }
         }
@@ -114,5 +120,4 @@ public function removeDirective(VirtualHostDirective $d)
 
         return $this;
     }
-
 }
diff --git a/tests/Documents/GraphLookup/Airport.php b/tests/Documents/GraphLookup/Airport.php
index 6b94d1b20b..0d5b32203a 100644
--- a/tests/Documents/GraphLookup/Airport.php
+++ b/tests/Documents/GraphLookup/Airport.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\GraphLookup;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Documents/GraphLookup/Employee.php b/tests/Documents/GraphLookup/Employee.php
index 415ab710e6..a3ed911496 100644
--- a/tests/Documents/GraphLookup/Employee.php
+++ b/tests/Documents/GraphLookup/Employee.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\GraphLookup;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -25,7 +27,7 @@ class Employee
     /** @ODM\ReferenceMany(targetDocument=Employee::class, mappedBy="reportsTo") */
     public $reportingEmployees;
 
-    public function __construct($name, Employee $reportsTo = null)
+    public function __construct($name, ?Employee $reportsTo = null)
     {
         $this->name = $name;
         $this->reportsTo = $reportsTo;
diff --git a/tests/Documents/GraphLookup/ReportingHierarchy.php b/tests/Documents/GraphLookup/ReportingHierarchy.php
index 43e5161b33..fc8d1479a6 100644
--- a/tests/Documents/GraphLookup/ReportingHierarchy.php
+++ b/tests/Documents/GraphLookup/ReportingHierarchy.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\GraphLookup;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Documents/GraphLookup/Traveller.php b/tests/Documents/GraphLookup/Traveller.php
index 7935537615..ee8ede7167 100644
--- a/tests/Documents/GraphLookup/Traveller.php
+++ b/tests/Documents/GraphLookup/Traveller.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\GraphLookup;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Group.php b/tests/Documents/Group.php
index e7475e64f2..f89ed75566 100644
--- a/tests/Documents/Group.php
+++ b/tests/Documents/Group.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/GuestServer.php b/tests/Documents/GuestServer.php
index c42a9cd3a2..9f5162c176 100644
--- a/tests/Documents/GuestServer.php
+++ b/tests/Documents/GuestServer.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -7,4 +9,4 @@
 /** @ODM\Document */
 class GuestServer extends Server
 {
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/IdentifiedChapter.php b/tests/Documents/IdentifiedChapter.php
index 92950f3aa6..dfaefee5a0 100644
--- a/tests/Documents/IdentifiedChapter.php
+++ b/tests/Documents/IdentifiedChapter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Documents/Issue.php b/tests/Documents/Issue.php
index 8fbcc7c792..88049dbbe7 100644
--- a/tests/Documents/Issue.php
+++ b/tests/Documents/Issue.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Manager.php b/tests/Documents/Manager.php
index 2e10ead29d..50b9ef1e48 100644
--- a/tests/Documents/Manager.php
+++ b/tests/Documents/Manager.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -8,7 +10,7 @@
 class Manager extends BaseEmployee
 {
     /** @ODM\ReferenceMany(targetDocument="Documents\Project") */
-    private $projects = array();
+    private $projects = [];
 
     public function getProjects()
     {
@@ -19,4 +21,4 @@ public function addProject(Project $project)
     {
         $this->projects[] = $project;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Message.php b/tests/Documents/Message.php
index f60fbaf834..100eb6d845 100644
--- a/tests/Documents/Message.php
+++ b/tests/Documents/Message.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/OtherSubProject.php b/tests/Documents/OtherSubProject.php
index 7c952b4686..3281784b70 100644
--- a/tests/Documents/OtherSubProject.php
+++ b/tests/Documents/OtherSubProject.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -7,4 +9,4 @@
 /** @ODM\Document */
 class OtherSubProject extends Project
 {
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Page.php b/tests/Documents/Page.php
index bec3e50be1..70f2c373f9 100644
--- a/tests/Documents/Page.php
+++ b/tests/Documents/Page.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Phonebook.php b/tests/Documents/Phonebook.php
index e3683195ec..9c85c47e37 100644
--- a/tests/Documents/Phonebook.php
+++ b/tests/Documents/Phonebook.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
diff --git a/tests/Documents/Phonenumber.php b/tests/Documents/Phonenumber.php
index e054a0f006..7de1591ef0 100644
--- a/tests/Documents/Phonenumber.php
+++ b/tests/Documents/Phonenumber.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -13,7 +15,7 @@ class Phonenumber
     /** @ODM\ReferenceOne(targetDocument="User", cascade={"persist"}) */
     private $lastCalledBy;
 
-    public function __construct($phonenumber = null, User $lastCalledBy = null)
+    public function __construct($phonenumber = null, ?User $lastCalledBy = null)
     {
         $this->phonenumber = $phonenumber;
         $this->lastCalledBy = $lastCalledBy;
@@ -34,7 +36,7 @@ public function getLastCalledBy()
         return $this->lastCalledBy;
     }
 
-    public function setLastCalledBy(User $lastCalledBy = null)
+    public function setLastCalledBy(?User $lastCalledBy = null)
     {
         $this->lastCalledBy = $lastCalledBy;
     }
diff --git a/tests/Documents/Product.php b/tests/Documents/Product.php
index b0edc1428f..62540eee7f 100644
--- a/tests/Documents/Product.php
+++ b/tests/Documents/Product.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /** @ODM\Document */
@@ -21,7 +24,7 @@ class Product
     public function __construct($name)
     {
         $this->name = $name;
-        $this->features = new \Doctrine\Common\Collections\ArrayCollection();
+        $this->features = new ArrayCollection();
     }
 
     public function addFeature(Feature $feature)
diff --git a/tests/Documents/Profile.php b/tests/Documents/Profile.php
index c489073067..7fb30ebcb5 100644
--- a/tests/Documents/Profile.php
+++ b/tests/Documents/Profile.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/ProfileNotify.php b/tests/Documents/ProfileNotify.php
index dcd2a432d8..484df32577 100644
--- a/tests/Documents/ProfileNotify.php
+++ b/tests/Documents/ProfileNotify.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -26,7 +28,7 @@ class ProfileNotify implements NotifyPropertyChanged
     private $images;
 
     /** @var PropertyChangedListener[] */
-    private $listeners = array();
+    private $listeners = [];
 
     public function __construct()
     {
diff --git a/tests/Documents/Project.php b/tests/Documents/Project.php
index 179a899325..61e2d4a802 100644
--- a/tests/Documents/Project.php
+++ b/tests/Documents/Project.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -28,7 +30,7 @@ class Project
      */
     private $subProjects;
 
-    public function __construct($name, Collection $subProjects = null)
+    public function __construct($name, ?Collection $subProjects = null)
     {
         $this->name = $name;
         $this->subProjects = $subProjects ? $subProjects : new ArrayCollection();
diff --git a/tests/Documents/ReferenceUser.php b/tests/Documents/ReferenceUser.php
index 088bd96eeb..13e172bb3a 100644
--- a/tests/Documents/ReferenceUser.php
+++ b/tests/Documents/ReferenceUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -28,7 +30,7 @@ class ReferenceUser
      *
      * @var User[]
      */
-    public $users = array();
+    public $users = [];
 
     /**
      * @ODM\ReferenceOne(targetDocument="Documents\User", storeAs="dbRef")
@@ -42,7 +44,7 @@ class ReferenceUser
      *
      * @var User[]
      */
-    public $parentUsers = array();
+    public $parentUsers = [];
 
     /**
      * @ODM\ReferenceOne(targetDocument="Documents\User", storeAs="dbRefWithDb")
@@ -56,7 +58,7 @@ class ReferenceUser
      *
      * @var User[]
      */
-    public $otherUsers = array();
+    public $otherUsers = [];
 
     /**
      * @ODM\ReferenceOne(targetDocument="Documents\User", storeAs="ref")
@@ -70,7 +72,7 @@ class ReferenceUser
      *
      * @var User[]
      */
-    public $referencedUsers = array();
+    public $referencedUsers = [];
 
     /**
      * @ODM\Field(type="string")
@@ -79,9 +81,6 @@ class ReferenceUser
      */
     public $name;
 
-    /**
-     * @param User $user
-     */
     public function setUser(User $user)
     {
         $this->user = $user;
@@ -95,9 +94,6 @@ public function getUser()
         return $this->user;
     }
 
-    /**
-     * @param User $user
-     */
     public function addUser(User $user)
     {
         $this->users[] = $user;
@@ -111,9 +107,6 @@ public function getUsers()
         return $this->users;
     }
 
-    /**
-     * @param User $parentUser
-     */
     public function setParentUser(User $parentUser)
     {
         $this->parentUser = $parentUser;
@@ -127,9 +120,6 @@ public function getParentUser()
         return $this->parentUser;
     }
 
-    /**
-     * @param User $parentUser
-     */
     public function addParentUser(User $parentUser)
     {
         $this->parentUsers[] = $parentUser;
@@ -143,9 +133,6 @@ public function getParentUsers()
         return $this->parentUsers;
     }
 
-    /**
-     * @param User $otherUser
-     */
     public function setOtherUser(User $otherUser)
     {
         $this->otherUser = $otherUser;
@@ -159,9 +146,6 @@ public function getOtherUser()
         return $this->otherUser;
     }
 
-    /**
-     * @param User $otherUser
-     */
     public function addOtherUser(User $otherUser)
     {
         $this->otherUsers[] = $otherUser;
@@ -175,9 +159,6 @@ public function getOtherUsers()
         return $this->otherUsers;
     }
 
-    /**
-     * @param User $referencedUser
-     */
     public function setReferencedUser(User $referencedUser)
     {
         $this->referencedUser = $referencedUser;
@@ -191,9 +172,6 @@ public function getreferencedUser()
         return $this->referencedUser;
     }
 
-    /**
-     * @param User $referencedUser
-     */
     public function addReferencedUser(User $referencedUser)
     {
         $this->referencedUsers[] = $referencedUser;
diff --git a/tests/Documents/Server.php b/tests/Documents/Server.php
index 3071892712..74e9b5329e 100644
--- a/tests/Documents/Server.php
+++ b/tests/Documents/Server.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Sharded/ShardedOne.php b/tests/Documents/Sharded/ShardedOne.php
index 9c218c3b8e..4669e7440b 100644
--- a/tests/Documents/Sharded/ShardedOne.php
+++ b/tests/Documents/Sharded/ShardedOne.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Sharded;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Sharded/ShardedOneWithDifferentKey.php b/tests/Documents/Sharded/ShardedOneWithDifferentKey.php
index 3c14ec9e29..e590aca836 100644
--- a/tests/Documents/Sharded/ShardedOneWithDifferentKey.php
+++ b/tests/Documents/Sharded/ShardedOneWithDifferentKey.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Sharded;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Sharded/ShardedUser.php b/tests/Documents/Sharded/ShardedUser.php
index 4b5984e235..af3bb0c3f0 100644
--- a/tests/Documents/Sharded/ShardedUser.php
+++ b/tests/Documents/Sharded/ShardedUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Sharded;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/SimpleReferenceUser.php b/tests/Documents/SimpleReferenceUser.php
index 3b76c3d7e6..915d596ffa 100644
--- a/tests/Documents/SimpleReferenceUser.php
+++ b/tests/Documents/SimpleReferenceUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -16,7 +18,7 @@ class SimpleReferenceUser
     public $user;
 
     /** @ODM\ReferenceMany(targetDocument="Documents\User", storeAs="id") */
-    public $users = array();
+    public $users = [];
 
     /** @ODM\Field(type="string") */
     public $name;
diff --git a/tests/Documents/Song.php b/tests/Documents/Song.php
index 824dd248c4..92db6a8356 100644
--- a/tests/Documents/Song.php
+++ b/tests/Documents/Song.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/SpecialUser.php b/tests/Documents/SpecialUser.php
index a38caa9952..8902183d59 100644
--- a/tests/Documents/SpecialUser.php
+++ b/tests/Documents/SpecialUser.php
@@ -1,14 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
-/** * @ODM\Document */
+/** @ODM\Document */
 class SpecialUser extends User
 {
     /** @ODM\Field(type="collection") */
-    private $rules = array();
+    private $rules = [];
 
     public function setRules(array $rules)
     {
@@ -19,4 +21,4 @@ public function getRules()
     {
         return $this->rules;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Strategy.php b/tests/Documents/Strategy.php
index 53a80b17c2..8fa5f381e2 100644
--- a/tests/Documents/Strategy.php
+++ b/tests/Documents/Strategy.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -11,11 +13,11 @@ class Strategy
     public $id;
 
     /** @ODM\Field(type="collection") */
-    public $logs = array();
+    public $logs = [];
 
     /** @ODM\EmbedMany(targetDocument="Message", strategy="set") */
-    public $messages = array();
+    public $messages = [];
 
     /** @ODM\ReferenceMany(targetDocument="Task", strategy="set") */
-    public $tasks = array();
+    public $tasks = [];
 }
diff --git a/tests/Documents/SubCategory.php b/tests/Documents/SubCategory.php
index e97314e183..da98b2fbe3 100644
--- a/tests/Documents/SubCategory.php
+++ b/tests/Documents/SubCategory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -7,4 +9,4 @@
 /** @ODM\EmbeddedDocument */
 class SubCategory extends BaseCategory
 {
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/SubProject.php b/tests/Documents/SubProject.php
index 7c2ef29306..07569bbdc6 100644
--- a/tests/Documents/SubProject.php
+++ b/tests/Documents/SubProject.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\Collection;
@@ -22,4 +24,4 @@ public function setIssues(Collection $issues)
     {
         $this->issues = $issues;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Documents/Tag.php b/tests/Documents/Tag.php
index 43da6264cd..03b765f035 100644
--- a/tests/Documents/Tag.php
+++ b/tests/Documents/Tag.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Task.php b/tests/Documents/Task.php
index 6f3e1b12de..6a86239b59 100644
--- a/tests/Documents/Task.php
+++ b/tests/Documents/Task.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Tournament/Participant.php b/tests/Documents/Tournament/Participant.php
index efdda5f673..165dc91863 100644
--- a/tests/Documents/Tournament/Participant.php
+++ b/tests/Documents/Tournament/Participant.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Tournament/ParticipantSolo.php b/tests/Documents/Tournament/ParticipantSolo.php
index 30cf8ab0a7..6966080abc 100644
--- a/tests/Documents/Tournament/ParticipantSolo.php
+++ b/tests/Documents/Tournament/ParticipantSolo.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Tournament/ParticipantTeam.php b/tests/Documents/Tournament/ParticipantTeam.php
index e6f77b9681..121d0d797f 100644
--- a/tests/Documents/Tournament/ParticipantTeam.php
+++ b/tests/Documents/Tournament/ParticipantTeam.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Tournament/Tournament.php b/tests/Documents/Tournament/Tournament.php
index 79f10cfb7d..ba58eb39d1 100644
--- a/tests/Documents/Tournament/Tournament.php
+++ b/tests/Documents/Tournament/Tournament.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
@@ -18,7 +20,7 @@ class Tournament
     private $name;
 
     /** @ODM\ReferenceMany(targetDocument="Participant", cascade={"all"}) */
-    protected $participants = array();
+    protected $participants = [];
 
     public function __construct($name)
     {
diff --git a/tests/Documents/Tournament/TournamentFootball.php b/tests/Documents/Tournament/TournamentFootball.php
index 9894f1b9bb..b8736f4e47 100644
--- a/tests/Documents/Tournament/TournamentFootball.php
+++ b/tests/Documents/Tournament/TournamentFootball.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/Tournament/TournamentTennis.php b/tests/Documents/Tournament/TournamentTennis.php
index 406e6e2c1f..7632a693eb 100644
--- a/tests/Documents/Tournament/TournamentTennis.php
+++ b/tests/Documents/Tournament/TournamentTennis.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents\Tournament;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/User.php b/tests/Documents/User.php
index 1c140cfd94..04a6733013 100644
--- a/tests/Documents/User.php
+++ b/tests/Documents/User.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
@@ -87,7 +89,7 @@ class User extends BaseDocument
     protected $embeddedReferenceManyInverse;
 
     /** @ODM\Field(type="collection") */
-    private $logs = array();
+    private $logs = [];
 
     public function __construct()
     {
@@ -161,7 +163,7 @@ public function getAddress()
         return $this->address;
     }
 
-    public function setAddress(Address $address = null)
+    public function setAddress(?Address $address = null)
     {
         $this->address = $address;
     }
diff --git a/tests/Documents/UserUpsert.php b/tests/Documents/UserUpsert.php
index 967c98ae8d..d895c7bb4e 100644
--- a/tests/Documents/UserUpsert.php
+++ b/tests/Documents/UserUpsert.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/UserUpsertChild.php b/tests/Documents/UserUpsertChild.php
index 78913fe4ca..32d1a10c21 100644
--- a/tests/Documents/UserUpsertChild.php
+++ b/tests/Documents/UserUpsertChild.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/UserUpsertIdStrategyNone.php b/tests/Documents/UserUpsertIdStrategyNone.php
index 01e3ee6255..a2eaf24f46 100644
--- a/tests/Documents/UserUpsertIdStrategyNone.php
+++ b/tests/Documents/UserUpsertIdStrategyNone.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/VersionedDocument.php b/tests/Documents/VersionedDocument.php
index b96a34d54e..f18bb21c54 100644
--- a/tests/Documents/VersionedDocument.php
+++ b/tests/Documents/VersionedDocument.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/Documents/VersionedUser.php b/tests/Documents/VersionedUser.php
index d3c331a191..fbce9284a4 100644
--- a/tests/Documents/VersionedUser.php
+++ b/tests/Documents/VersionedUser.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tests/NativePhpunitTask.php b/tests/NativePhpunitTask.php
index 203a041f34..914b041725 100644
--- a/tests/NativePhpunitTask.php
+++ b/tests/NativePhpunitTask.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 require_once 'PHPUnit/Framework.php';
 
 /**
@@ -18,86 +20,92 @@ class NativePhpunitTask extends Task
     private $haltonfailure = true;
     private $haltonerror = true;
 
-    public function setTestdirectory($directory) {
+    public function setTestdirectory($directory)
+    {
         $this->testdirectory = $directory;
     }
 
-    public function setTest($test) {
+    public function setTest($test)
+    {
         $this->test = $test;
     }
 
-    public function setTestfile($testfile) {
+    public function setTestfile($testfile)
+    {
         $this->testfile = $testfile;
     }
 
-    public function setJunitlogfile($junitlogfile) {
-        if (strlen($junitlogfile) == 0) {
-            $junitlogfile = NULL;
+    public function setJunitlogfile($junitlogfile)
+    {
+        if (strlen($junitlogfile) === 0) {
+            $junitlogfile = null;
         }
 
         $this->junitlogfile = $junitlogfile;
     }
 
-    public function setConfiguration($configuration) {
-        if (strlen($configuration) == 0) {
-            $configuration = NULL;
+    public function setConfiguration($configuration)
+    {
+        if (strlen($configuration) === 0) {
+            $configuration = null;
         }
 
         $this->configuration = $configuration;
     }
 
-    public function setCoverageClover($coverageClover) {
-        if (strlen($coverageClover) == 0) {
-            $coverageClover = NULL;
+    public function setCoverageClover($coverageClover)
+    {
+        if (strlen($coverageClover) === 0) {
+            $coverageClover = null;
         }
 
         $this->coverageClover = $coverageClover;
     }
 
-    public function setHaltonfailure($haltonfailures) {
+    public function setHaltonfailure($haltonfailures)
+    {
         $this->haltonfailure = $haltonfailures;
     }
 
-    public function setHaltonerror($haltonerrors) {
+    public function setHaltonerror($haltonerrors)
+    {
         $this->haltonerror = $haltonerrors;
     }
 
     public function init()
     {
-        require_once "PHPUnit/Runner/Version.php";
+        require_once 'PHPUnit/Runner/Version.php';
         $version = PHPUnit_Runner_Version::id();
 
-        if (version_compare($version, '3.4.0') < 0)
-        {
-            throw new BuildException("NativePHPUnitTask requires PHPUnit version >= 3.2.0", $this->getLocation());
+        if (version_compare($version, '3.4.0') < 0) {
+            throw new BuildException('NativePHPUnitTask requires PHPUnit version >= 3.2.0', $this->getLocation());
         }
 
         require_once 'PHPUnit/Util/Filter.php';
 
         // point PHPUnit_MAIN_METHOD define to non-existing method
-        if (!defined('PHPUnit_MAIN_METHOD'))
-        {
+        if (! defined('PHPUnit_MAIN_METHOD')) {
             define('PHPUnit_MAIN_METHOD', 'PHPUnitTask::undefined');
         }
     }
 
     public function main()
     {
-        if (!is_dir(realpath($this->testdirectory))) {
-            throw new BuildException("NativePHPUnitTask requires a Test Directory path given, '".$this->testdirectory."' given.");
+        if (! is_dir(realpath($this->testdirectory))) {
+            throw new BuildException("NativePHPUnitTask requires a Test Directory path given, '" . $this->testdirectory . "' given.");
         }
         set_include_path(realpath($this->testdirectory) . PATH_SEPARATOR . get_include_path());
 
         $printer = new NativePhpunitPrinter();
 
-        $arguments = array(
+        $arguments = [
             'configuration' => $this->configuration,
             'coverageClover' => $this->coverageClover,
             'junitLogfile' => $this->junitlogfile,
             'printer' => $printer,
-        );
+        ];
 
-        require_once "PHPUnit/TextUI/TestRunner.php";
+        require_once 'PHPUnit/TextUI/TestRunner.php';
         $runner = new PHPUnit_TextUI_TestRunner();
         $suite = $runner->getTest($this->test, $this->testfile, true);
 
@@ -105,32 +113,31 @@ public function main()
             $result = $runner->doRun($suite, $arguments);
             /* @var $result PHPUnit_Framework_TestResult */
 
-            if ( ($this->haltonfailure && $result->failureCount() > 0) || ($this->haltonerror && $result->errorCount() > 0) ) {
-                throw new BuildException("PHPUnit: ".$result->failureCount()." Failures and ".$result->errorCount()." Errors, ".
-                    "last failure message: ".$printer->getMessages());
+            if (($this->haltonfailure && $result->failureCount() > 0) || ($this->haltonerror && $result->errorCount() > 0)) {
+                throw new BuildException('PHPUnit: ' . $result->failureCount() . ' Failures and ' . $result->errorCount() . ' Errors, ' .
+                    'last failure message: ' . $printer->getMessages());
             }
 
-            $this->log("PHPUnit Success: ".count($result->passed())." tests passed, no ".
-                "failures (".$result->skippedCount()." skipped, ".$result->notImplementedCount()." not implemented)");
+            $this->log('PHPUnit Success: ' . count($result->passed()) . ' tests passed, no ' .
+                'failures (' . $result->skippedCount() . ' skipped, ' . $result->notImplementedCount() . ' not implemented)');
 
             // Hudson for example doesn't like the backslash in class names
             if (file_exists($this->coverageClover)) {
-                $this->log("Generated Clover Coverage XML to: ".$this->coverageClover);
+                $this->log('Generated Clover Coverage XML to: ' . $this->coverageClover);
                 $content = file_get_contents($this->coverageClover);
-                $content = str_replace("\\", ".", $content);
+                $content = str_replace('\\', '.', $content);
                 file_put_contents($this->coverageClover, $content);
                 unset($content);
             }
-
-        } catch(\Exception $e) {
-            throw new BuildException("NativePhpunitTask failed: ".$e->getMessage());
+        } catch (Throwable $e) {
+            throw new BuildException('NativePhpunitTask failed: ' . $e->getMessage());
         }
     }
 }
 
 class NativePhpunitPrinter extends PHPUnit_Util_Printer implements PHPUnit_Framework_TestListener
 {
-    private $_messages = array();
+    private $_messages = [];
 
     public function write($buffer)
     {
@@ -145,92 +152,74 @@ public function getMessages()
     /**
      * An error occurred.
      *
-     * @param  PHPUnit_Framework_Test $test
-     * @param  Exception              $e
-     * @param  float                  $time
+     * @param  Exception $e
+     * @param  float     $time
      */
-    public function addError(PHPUnit_Framework_Test $test, Exception $e, $time)
+    public function addError(PHPUnit_Framework_Test $test, Throwable $e, $time)
     {
-        $this->_messages[] = "Test ERROR: ".$test->getName().": ".$e->getMessage();
+        $this->_messages[] = 'Test ERROR: ' . $test->getName() . ': ' . $e->getMessage();
     }
 
     /**
      * A failure occurred.
      *
-     * @param  PHPUnit_Framework_Test                 $test
-     * @param  PHPUnit_Framework_AssertionFailedError $e
-     * @param  float                                  $time
+     * @param  float $time
      */
     public function addFailure(PHPUnit_Framework_Test $test, PHPUnit_Framework_AssertionFailedError $e, $time)
     {
-        $this->_messages[] = "Test FAILED: ".$test->getName().": ".$e->getMessage();
+        $this->_messages[] = 'Test FAILED: ' . $test->getName() . ': ' . $e->getMessage();
     }
 
     /**
      * Incomplete test.
      *
-     * @param  PHPUnit_Framework_Test $test
-     * @param  Exception              $e
-     * @param  float                  $time
+     * @param  Exception $e
+     * @param  float     $time
      */
-    public function addIncompleteTest(PHPUnit_Framework_Test $test, Exception $e, $time)
+    public function addIncompleteTest(PHPUnit_Framework_Test $test, Throwable $e, $time)
     {
-
     }
 
     /**
      * Skipped test.
      *
-     * @param  PHPUnit_Framework_Test $test
-     * @param  Exception              $e
-     * @param  float                  $time
-     * @since  Method available since Release 3.0.0
+     * @param  Exception $e
+     * @param  float     $time
      */
-    public function addSkippedTest(PHPUnit_Framework_Test $test, Exception $e, $time)
+    public function addSkippedTest(PHPUnit_Framework_Test $test, Throwable $e, $time)
     {
-
     }
 
     /**
      * A test suite started.
      *
-     * @param  PHPUnit_Framework_TestSuite $suite
-     * @since  Method available since Release 2.2.0
      */
     public function startTestSuite(PHPUnit_Framework_TestSuite $suite)
     {
-
     }
 
     /**
      * A test suite ended.
      *
-     * @param  PHPUnit_Framework_TestSuite $suite
-     * @since  Method available since Release 2.2.0
      */
     public function endTestSuite(PHPUnit_Framework_TestSuite $suite)
     {
-
     }
 
     /**
      * A test started.
      *
-     * @param  PHPUnit_Framework_Test $test
      */
     public function startTest(PHPUnit_Framework_Test $test)
     {
-
     }
 
     /**
      * A test ended.
      *
-     * @param  PHPUnit_Framework_Test $test
-     * @param  float                  $time
+     * @param  float $time
      */
     public function endTest(PHPUnit_Framework_Test $test, $time)
     {
-        
     }
 }
diff --git a/tests/Stubs/DocumentManager.php b/tests/Stubs/DocumentManager.php
index 7722c39403..ab8f2153be 100644
--- a/tests/Stubs/DocumentManager.php
+++ b/tests/Stubs/DocumentManager.php
@@ -1,15 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Stubs;
 
+use Doctrine\Common\EventManager;
 use Doctrine\ODM\MongoDB\DocumentManager as BaseDocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
-use Doctrine\Common\EventManager;
 
 class DocumentManager extends BaseDocumentManager
 {
-
-    protected $classMetadatas = array();
+    protected $classMetadatas = [];
 
     private $_eventManager;
 
@@ -30,10 +31,9 @@ public function setClassMetadata($className, ClassMetadata $class)
 
     public function getClassMetadata($className)
     {
-        if ( ! isset($this->classMetadatas[$className])) {
+        if (! isset($this->classMetadatas[$className])) {
             throw new \InvalidArgumentException('Metadata for class ' . $className . ' doesn\'t exist, try calling ->setClassMetadata() first');
         }
         return $this->classMetadatas[$className];
     }
-
 }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index ad0856a1f4..4483540f04 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,8 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 use Doctrine\Common\Annotations\AnnotationRegistry;
 
-if (!file_exists($file = __DIR__.'/../vendor/autoload.php')) {
+if (! file_exists($file = __DIR__ . '/../vendor/autoload.php')) {
     throw new RuntimeException('Install dependencies to run test suite.');
 }
 
diff --git a/tools/sandbox/Documents/Account.php b/tools/sandbox/Documents/Account.php
index 3d77de0b06..0d5f016ae4 100644
--- a/tools/sandbox/Documents/Account.php
+++ b/tools/sandbox/Documents/Account.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tools/sandbox/Documents/Address.php b/tools/sandbox/Documents/Address.php
index a138e7df7e..d46da03078 100644
--- a/tools/sandbox/Documents/Address.php
+++ b/tools/sandbox/Documents/Address.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tools/sandbox/Documents/Phonenumber.php b/tools/sandbox/Documents/Phonenumber.php
index 2bf4b4f4ed..fd9b05d165 100644
--- a/tools/sandbox/Documents/Phonenumber.php
+++ b/tools/sandbox/Documents/Phonenumber.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
diff --git a/tools/sandbox/Documents/User.php b/tools/sandbox/Documents/User.php
index d64dc3e535..bacc08afe8 100644
--- a/tools/sandbox/Documents/User.php
+++ b/tools/sandbox/Documents/User.php
@@ -1,9 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use function md5;
 
 /** @ODM\Document(collection="users") */
 class User
diff --git a/tools/sandbox/Documents/UserRepository.php b/tools/sandbox/Documents/UserRepository.php
index 0bd203e357..5cc39a1957 100644
--- a/tools/sandbox/Documents/UserRepository.php
+++ b/tools/sandbox/Documents/UserRepository.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\DocumentRepository;
diff --git a/tools/sandbox/cli-config.php b/tools/sandbox/cli-config.php
index 7d5f026344..50ff3f4dd1 100644
--- a/tools/sandbox/cli-config.php
+++ b/tools/sandbox/cli-config.php
@@ -1,10 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 use Doctrine\ODM\MongoDB\Tools\Console\Helper\DocumentManagerHelper;
 use Symfony\Component\Console\Helper\HelperSet;
 
 require_once __DIR__ . '/config.php';
 
-$helperSet = new HelperSet(array(
+$helperSet = new HelperSet([
     'dm' => new DocumentManagerHelper($dm),
-));
+]);
diff --git a/tools/sandbox/config.php b/tools/sandbox/config.php
index 2849e88485..a206a98d27 100644
--- a/tools/sandbox/config.php
+++ b/tools/sandbox/config.php
@@ -1,12 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 use Doctrine\Common\Annotations\AnnotationRegistry;
 use Doctrine\MongoDB\Connection;
 use Doctrine\ODM\MongoDB\Configuration;
 use Doctrine\ODM\MongoDB\DocumentManager;
 use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
 
-if (!file_exists($file = __DIR__.'/../../vendor/autoload.php')) {
+if (! file_exists($file = __DIR__ . '/../../vendor/autoload.php')) {
     throw new RuntimeException('Install dependencies to run this script.');
 }
 
diff --git a/tools/sandbox/index.php b/tools/sandbox/index.php
index f598a11108..07384ebf84 100644
--- a/tools/sandbox/index.php
+++ b/tools/sandbox/index.php
@@ -1,10 +1,8 @@
 <?php
 
+declare(strict_types=1);
+
 require_once __DIR__ . '/config.php';
 
-use Documents\Account;
-use Documents\Address;
-use Documents\Phonenumber;
-use Documents\User;
 
 // Your code here...
diff --git a/tools/sandbox/mongodb.php b/tools/sandbox/mongodb.php
index 0212e420a0..d989d16083 100644
--- a/tools/sandbox/mongodb.php
+++ b/tools/sandbox/mongodb.php
@@ -1,21 +1,31 @@
 <?php
 
+declare(strict_types=1);
+
 require __DIR__ . '/cli-config.php';
+use Doctrine\ODM\MongoDB\Tools\Console\Command\ClearCache\MetadataCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\GenerateHydratorsCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\GenerateProxiesCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\QueryCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\CreateCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\DropCommand;
+use Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\UpdateCommand;
+use Symfony\Component\Console\Application;
 
-$app = new \Symfony\Component\Console\Application('Doctrine MongoDB ODM');
+$app = new Application('Doctrine MongoDB ODM');
 
 if (isset($helperSet)) {
     $app->setHelperSet($helperSet);
 }
 
-$app->addCommands(array(
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\GenerateHydratorsCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\GenerateProxiesCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\QueryCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\ClearCache\MetadataCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\CreateCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\DropCommand(),
-    new \Doctrine\ODM\MongoDB\Tools\Console\Command\Schema\UpdateCommand(),
-));
+$app->addCommands([
+    new GenerateHydratorsCommand(),
+    new GenerateProxiesCommand(),
+    new QueryCommand(),
+    new MetadataCommand(),
+    new CreateCommand(),
+    new DropCommand(),
+    new UpdateCommand(),
+]);
 
 $app->run();