diff --git a/.gitattributes b/.gitattributes
index 3edeb7c2..040cc07f 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,3 +1,4 @@
 .* export-ignore
 *.md export-ignore
 Tests/* export-ignore
+Resources/doc/* export-ignore
diff --git a/.github/ISSUE_TEMPLATE.md b/.github/ISSUE_TEMPLATE.md
index ef5bfcf1..821219ae 100644
--- a/.github/ISSUE_TEMPLATE.md
+++ b/.github/ISSUE_TEMPLATE.md
@@ -14,12 +14,14 @@
 
 ```
 $ composer show --latest 'sonata-project/*'
+# Put the result here.
 ```
 
 #### Symfony packages
 
 ```
 $ composer show --latest 'symfony/*'
+# Put the result here.
 ```
 
 #### PHP version
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index 57fb782b..a885737e 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -9,8 +9,6 @@
 -->
 I am targeting this branch, because {reason}.
 
-In case of bug fix, `3.x` **MUST** be targeted.
-
 <!--
     Specify which issues will be fixed/closed.
     Remove it if this is not related.
diff --git a/.styleci.yml b/.styleci.yml
index b92598db..6424eea7 100644
--- a/.styleci.yml
+++ b/.styleci.yml
@@ -7,9 +7,8 @@
 preset: symfony
 
 enabled:
-  - class_keyword_remove
   - combine_consecutive_unsets
-  - long_array_syntax
+  - short_array_syntax
   - newline_after_open_tag
   - no_php4_constructor
   - no_useless_else
@@ -24,6 +23,7 @@ enabled:
 finder:
   exclude:
     - 'Tests/Fixtures'
+    - 'tests/Fixtures'
     # ecommerce special case:
     - 'Resources/skeleton'
     # ignore vendor assets
diff --git a/.travis.yml b/.travis.yml
index 0f87076e..c44fa943 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,17 +10,16 @@ branches:
 language: php
 
 php:
-  - '5.3'
-  - '5.4'
-  - '5.5'
   - '5.6'
+  - '7.0'
+  - '7.1'
   - nightly
 
 services:
   - mongodb
 
 sudo: false
-dist: precise
+dist: trusty
 
 cache:
   pip: true
@@ -38,38 +37,31 @@ env:
 matrix:
   fast_finish: true
   include:
-    - php: '5.6'
+    - php: '7.1'
       env: TARGET=docs
-    - php: '5.6'
+    - php: '7.1'
       env: TARGET=lint
-    - php: '5.3'
-      env: COMPOSER_FLAGS="--prefer-lowest"
-    - php: '5.6'
-      env: SYMFONY=2.3.*
-    - php: '5.6'
-      env: SYMFONY=2.7.*
     - php: '5.6'
+      env: COMPOSER_FLAGS="--prefer-lowest"
+    - php: '7.1'
       env: SYMFONY=2.8.*
-    - php: '5.6'
+    - php: '7.1'
       env: SYMFONY=3.2.*
-    - php: '5.6'
+    - php: '7.1'
       env: SYMFONY=3.3.*
-    - php: '5.6'
-      env: SYMFONY=dev-master@dev
-    - php: '5.6'
+    - php: '7.1'
+      env: SYMFONY='dev-master as 3.3'
+    - php: '7.1'
       env: SONATA_ADMIN=3.*
-    - php: '5.6'
-      env: SONATA_ADMIN=dev-master@dev
-    - php: '5.6'
+    - php: '7.1'
+      env: SONATA_ADMIN='dev-master as 3'
+    - php: '7.1'
       env: SYMFONY_DEPRECATIONS_HELPER=0
-    - php: hhvm
-      dist: trusty
   allow_failures:
     - php: nightly
-    - php: hhvm
     - env: SYMFONY_DEPRECATIONS_HELPER=0
-    - env: SYMFONY=dev-master@dev
-    - env: SONATA_ADMIN=dev-master@dev
+    - env: SYMFONY='dev-master as 3.3'
+    - env: SONATA_ADMIN='dev-master as 3'
 
 before_install:
   - git remote add upstream ${UPSTREAM_URL} && git fetch --all
diff --git a/.travis/before_install_test.sh b/.travis/before_install_test.sh
index 81625a31..e6eb71b4 100755
--- a/.travis/before_install_test.sh
+++ b/.travis/before_install_test.sh
@@ -1,27 +1,19 @@
 #!/usr/bin/env sh
 set -ev
 
-if [ "${TRAVIS_PHP_VERSION}" != "hhvm" ]; then
-    PHP_INI_DIR="$HOME/.phpenv/versions/$(phpenv version-name)/etc/conf.d/"
-    TRAVIS_INI_FILE="$PHP_INI_DIR/travis.ini"
-    echo "memory_limit=3072M" >> "$TRAVIS_INI_FILE"
+PHP_INI_DIR="$HOME/.phpenv/versions/$(phpenv version-name)/etc/conf.d/"
+TRAVIS_INI_FILE="$PHP_INI_DIR/travis.ini"
+echo "memory_limit=3072M" >> "$TRAVIS_INI_FILE"
 
-        if [ "$TRAVIS_PHP_VERSION" '<' '5.4' ]; then
-        XDEBUG_INI_FILE="$PHP_INI_DIR/xdebug.ini"
-        if [ -f  "$XDEBUG_INI_FILE" ]; then
-            mv "$XDEBUG_INI_FILE" /tmp
-        fi
-    fi
-    
-        if [ "$TRAVIS_PHP_VERSION" '<' '7.0' ]; then
-        echo "extension=mongo.so" >> "$TRAVIS_INI_FILE"
-    else
-        echo "extension=mongodb.so" >> "$TRAVIS_INI_FILE"
 
-        # Backwards compatibility with old mongo extension
-        composer require "alcaeus/mongo-php-adapter" --no-update
-    fi
-    fi
+if [ "$TRAVIS_PHP_VERSION" '<' '7.0' ]; then
+    echo "extension=mongo.so" >> "$TRAVIS_INI_FILE"
+else
+    echo "extension=mongodb.so" >> "$TRAVIS_INI_FILE"
+
+    # Backwards compatibility with old mongo extension
+    composer require "alcaeus/mongo-php-adapter" --ignore-platform-reqs
+fi
 
 sed --in-place "s/\"dev-master\":/\"dev-${TRAVIS_COMMIT}\":/" composer.json
 
diff --git a/.travis/before_script_test.sh b/.travis/before_script_test.sh
index 936d4f59..87b47509 100644
--- a/.travis/before_script_test.sh
+++ b/.travis/before_script_test.sh
@@ -1,10 +1,3 @@
 #!/usr/bin/env bash
 set -ev
 
-if [ "$TRAVIS_PHP_VERSION" != "hhvm" ] && [ "$TRAVIS_PHP_VERSION" '<' '5.4' ]; then
-    PHP_INI_DIR="$HOME/.phpenv/versions/$(phpenv version-name)/etc/conf.d/"
-    XDEBUG_INI_FILE="/tmp/xdebug.ini"
-    if [ -f  "$XDEBUG_INI_FILE" ]; then
-        mv "$XDEBUG_INI_FILE" "$PHP_INI_DIR"
-    fi
-fi
diff --git a/.travis/install_test.sh b/.travis/install_test.sh
index b15f8f87..d254afc4 100755
--- a/.travis/install_test.sh
+++ b/.travis/install_test.sh
@@ -4,12 +4,7 @@ set -ev
 mkdir --parents "${HOME}/bin"
 
 # PHPUnit install
-if [ ${TRAVIS_PHP_VERSION} '<' '5.6' ]; then
-    PHPUNIT_PHAR=phpunit-4.8.phar
-else
-    PHPUNIT_PHAR=phpunit-5.7.phar
-fi
-wget "https://phar.phpunit.de/${PHPUNIT_PHAR}" --output-document="${HOME}/bin/phpunit"
+wget "https://phar.phpunit.de/phpunit-5.7.phar" --output-document="${HOME}/bin/phpunit"
 chmod u+x "${HOME}/bin/phpunit"
 
 # Coveralls client install
@@ -19,6 +14,8 @@ chmod u+x "${HOME}/bin/coveralls"
 # To be removed when these issues are resolved:
 # https://github.com/composer/composer/issues/5355
 # https://github.com/composer/composer/issues/5030
-composer update --prefer-dist --no-interaction --prefer-stable --quiet --ignore-platform-reqs
+if [ "${COMPOSER_FLAGS}" = '--prefer-lowest' ]; then
+    composer update --prefer-dist --no-interaction --prefer-stable --quiet --ignore-platform-reqs
+fi
 
 composer update --prefer-dist --no-interaction --prefer-stable ${COMPOSER_FLAGS}
diff --git a/Admin/FieldDescription.php b/Admin/FieldDescription.php
index a97da88d..6d9970b6 100644
--- a/Admin/FieldDescription.php
+++ b/Admin/FieldDescription.php
@@ -20,7 +20,7 @@ class FieldDescription extends BaseFieldDescription
      */
     public function __construct()
     {
-        $this->parentAssociationMappings = array();
+        $this->parentAssociationMappings = [];
     }
 
     /**
diff --git a/Builder/DatagridBuilder.php b/Builder/DatagridBuilder.php
index 902b79ed..c7d20284 100644
--- a/Builder/DatagridBuilder.php
+++ b/Builder/DatagridBuilder.php
@@ -102,7 +102,7 @@ public function addFilter(DatagridInterface $datagrid, $type, FieldDescriptionIn
 
             foreach ($options as $name => $value) {
                 if (is_array($value)) {
-                    $fieldDescription->setOption($name, array_merge($value, $fieldDescription->getOption($name, array())));
+                    $fieldDescription->setOption($name, array_merge($value, $fieldDescription->getOption($name, [])));
                 } else {
                     $fieldDescription->setOption($name, $fieldDescription->getOption($name, $value));
                 }
@@ -114,7 +114,7 @@ public function addFilter(DatagridInterface $datagrid, $type, FieldDescriptionIn
         $this->fixFieldDescription($admin, $fieldDescription);
         $admin->addFilterFieldDescription($fieldDescription->getName(), $fieldDescription);
 
-        $fieldDescription->mergeOption('field_options', array('required' => false));
+        $fieldDescription->mergeOption('field_options', ['required' => false]);
         $filter = $this->filterFactory->create($fieldDescription->getName(), $type, $fieldDescription->getOptions());
 
         if (false !== $filter->getLabel() && !$filter->getLabel()) {
@@ -130,17 +130,17 @@ public function addFilter(DatagridInterface $datagrid, $type, FieldDescriptionIn
      *
      * @return \Sonata\AdminBundle\Datagrid\DatagridInterface
      */
-    public function getBaseDatagrid(AdminInterface $admin, array $values = array())
+    public function getBaseDatagrid(AdminInterface $admin, array $values = [])
     {
         $pager = new Pager();
         $pager->setCountColumn($admin->getModelManager()->getIdentifierFieldNames($admin->getClass()));
 
-        $defaultOptions = array();
+        $defaultOptions = [];
         if ($this->csrfTokenEnabled) {
             $defaultOptions['csrf_protection'] = false;
         }
 
-        $formBuilder = $this->formFactory->createNamedBuilder('filter', 'form', array(), $defaultOptions);
+        $formBuilder = $this->formFactory->createNamedBuilder('filter', 'form', [], $defaultOptions);
 
         return new Datagrid($admin->createQuery(), $admin->getList(), $pager, $formBuilder, $values);
     }
diff --git a/Builder/FormContractor.php b/Builder/FormContractor.php
index 5b203009..416f9422 100644
--- a/Builder/FormContractor.php
+++ b/Builder/FormContractor.php
@@ -60,7 +60,7 @@ public function fixFieldDescription(AdminInterface $admin, FieldDescriptionInter
         $fieldDescription->setAdmin($admin);
         $fieldDescription->setOption('edit', $fieldDescription->getOption('edit', 'standard'));
 
-        if (in_array($fieldDescription->getMappingType(), array(ClassMetadataInfo::ONE, ClassMetadataInfo::MANY))) {
+        if (in_array($fieldDescription->getMappingType(), [ClassMetadataInfo::ONE, ClassMetadataInfo::MANY])) {
             $admin->attachAdminClass($fieldDescription);
         }
     }
@@ -76,7 +76,7 @@ public function getFormFactory()
     /**
      * {@inheritdoc}
      */
-    public function getFormBuilder($name, array $options = array())
+    public function getFormBuilder($name, array $options = [])
     {
         return $this->getFormFactory()->createNamedBuilder($name, 'form', null, $options);
     }
@@ -86,17 +86,17 @@ public function getFormBuilder($name, array $options = array())
      */
     public function getDefaultOptions($type, FieldDescriptionInterface $fieldDescription)
     {
-        $options = array();
+        $options = [];
         $options['sonata_field_description'] = $fieldDescription;
 
         // NEXT_MAJOR: Check only against FQCNs when dropping support for Symfony <2.8
-        if ($this->checkFormType($type, array(
+        if ($this->checkFormType($type, [
             'sonata_type_model',
             'sonata_type_model_list',
-        )) || $this->checkFormClass($type, array(
+        ]) || $this->checkFormClass($type, [
             'Sonata\AdminBundle\Form\Type\ModelType',
             'Sonata\AdminBundle\Form\Type\ModelListType',
-        ))) {
+        ])) {
             if ('list' == $fieldDescription->getOption('edit')) {
                 throw new \LogicException('The ``sonata_type_model`` type does not accept an ``edit`` option anymore, please review the UPGRADE-2.1.md file from the SonataAdminBundle');
             }
@@ -104,7 +104,7 @@ public function getDefaultOptions($type, FieldDescriptionInterface $fieldDescrip
             $options['class'] = $fieldDescription->getTargetEntity();
             $options['model_manager'] = $fieldDescription->getAdmin()->getModelManager();
             // NEXT_MAJOR: Check only against FQCNs when dropping support for Symfony <2.8
-        } elseif ($this->checkFormType($type, array('sonata_type_admin')) || $this->checkFormClass($type, array('Sonata\AdminBundle\Form\Type\AdminType'))) {
+        } elseif ($this->checkFormType($type, ['sonata_type_admin']) || $this->checkFormClass($type, ['Sonata\AdminBundle\Form\Type\AdminType'])) {
             if (!$fieldDescription->getAssociationAdmin()) {
                 throw new \RuntimeException(sprintf('The current field `%s` is not linked to an admin. Please create one for the target entity : `%s`', $fieldDescription->getName(), $fieldDescription->getTargetEntity()));
             }
@@ -112,7 +112,7 @@ public function getDefaultOptions($type, FieldDescriptionInterface $fieldDescrip
             $options['data_class'] = $fieldDescription->getAssociationAdmin()->getClass();
             $fieldDescription->setOption('edit', $fieldDescription->getOption('edit', 'admin'));
             // NEXT_MAJOR: Check only against FQCNs when dropping support for Symfony <2.8
-        } elseif ($this->checkFormType($type, array('sonata_type_collection')) || $this->checkFormClass($type, array('Sonata\CoreBundle\Form\Type\CollectionType'))) {
+        } elseif ($this->checkFormType($type, ['sonata_type_collection']) || $this->checkFormClass($type, ['Sonata\CoreBundle\Form\Type\CollectionType'])) {
             if (!$fieldDescription->getAssociationAdmin()) {
                 throw new \RuntimeException(sprintf('The current field `%s` is not linked to an admin. Please create one for the target entity : `%s`', $fieldDescription->getName(), $fieldDescription->getTargetEntity()));
             }
@@ -123,10 +123,10 @@ public function getDefaultOptions($type, FieldDescriptionInterface $fieldDescrip
                 'Sonata\AdminBundle\Form\Type\AdminType'
             ;
             $options['modifiable'] = true;
-            $options['type_options'] = array(
+            $options['type_options'] = [
                 'sonata_field_description' => $fieldDescription,
                 'data_class' => $fieldDescription->getAssociationAdmin()->getClass(),
-            );
+            ];
         }
 
         return $options;
diff --git a/Builder/ListBuilder.php b/Builder/ListBuilder.php
index f5fe245d..3abefdc7 100644
--- a/Builder/ListBuilder.php
+++ b/Builder/ListBuilder.php
@@ -22,13 +22,13 @@ class ListBuilder implements ListBuilderInterface
 {
     protected $guesser;
 
-    protected $templates = array();
+    protected $templates = [];
 
     /**
      * @param \Sonata\AdminBundle\Guesser\TypeGuesserInterface $guesser
      * @param array                                            $templates
      */
-    public function __construct(TypeGuesserInterface $guesser, array $templates = array())
+    public function __construct(TypeGuesserInterface $guesser, array $templates = [])
     {
         $this->guesser = $guesser;
         $this->templates = $templates;
@@ -37,7 +37,7 @@ public function __construct(TypeGuesserInterface $guesser, array $templates = ar
     /**
      * {@inheritdoc}
      */
-    public function getBaseList(array $options = array())
+    public function getBaseList(array $options = [])
     {
         return new FieldDescriptionCollection();
     }
@@ -130,7 +130,7 @@ public function fixFieldDescription(AdminInterface $admin, FieldDescriptionInter
             $fieldDescription->setTemplate($template);
         }
 
-        if (in_array($fieldDescription->getMappingType(), array(ClassMetadataInfo::ONE, ClassMetadataInfo::MANY))) {
+        if (in_array($fieldDescription->getMappingType(), [ClassMetadataInfo::ONE, ClassMetadataInfo::MANY])) {
             $admin->attachAdminClass($fieldDescription);
         }
     }
diff --git a/Builder/ShowBuilder.php b/Builder/ShowBuilder.php
index 6806460f..af6c2fb4 100644
--- a/Builder/ShowBuilder.php
+++ b/Builder/ShowBuilder.php
@@ -39,7 +39,7 @@ public function __construct(TypeGuesserInterface $guesser, array $templates)
      *
      * @return \Sonata\AdminBundle\Admin\FieldDescriptionCollection
      */
-    public function getBaseList(array $options = array())
+    public function getBaseList(array $options = [])
     {
         return new FieldDescriptionCollection();
     }
@@ -121,7 +121,7 @@ public function fixFieldDescription(AdminInterface $admin, FieldDescriptionInter
             $fieldDescription->setTemplate($template);
         }
 
-        if (in_array($fieldDescription->getMappingType(), array(ClassMetadataInfo::ONE, ClassMetadataInfo::MANY))) {
+        if (in_array($fieldDescription->getMappingType(), [ClassMetadataInfo::ONE, ClassMetadataInfo::MANY])) {
             $admin->attachAdminClass($fieldDescription);
         }
     }
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0d73fee9..d57776f4 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -113,9 +113,9 @@ Some rules have to be respected about the test:
   * `@codeCoverageIgnore`
   * `@codeCoverageIgnoreStart`
   * `@codeCoverageIgnoreEnd`
-* All test methods should be prefixed by `test`. Example: `public function testItReturnsNull()`.
-* All test method names must be in camel case format.
+* All test methods must be prefixed by `test`. Example: `public function testItReturnsNull()`.
 * As opposed, the `@test` annotation is prohibited.
+* All test method names must be in camel case format.
 * Most of the time, the test class should have the same name as the targeted class, suffixed by `Test`.
 * The `@expectedException*` annotations are prohibited. Use `PHPUnit_Framework_TestCase::setExpectedException()`.
 
@@ -191,7 +191,6 @@ Here is a short table resuming on which you have to start:
 Kind of modification | Backward Compatible (BC) | Type of release | Branch to target        | Label |
 -------------------- | ------------------------ | --------------- | ----------------------- | ----- |
 Bug fixes            | Yes                      | Patch           | `3.x`   | |
-Bug fixes            | Not on legacy            | Patch           | `3.x`   | |
 Bug fixes            | No (Only if no choice)   | Major           | `master` | |
 Feature              | Yes                      | Minor           | `3.x`   | |
 Feature              | No (Only if no choice)   | Major           | `master` | |
@@ -199,12 +198,8 @@ Deprecation          | Yes (Have to)            | Minor           | `3.x`   | |
 Deprecation removal  | No (Can't be)            | Major           | `master` | |
 
 Notes:
-  * Branch `3.x` is the branch of the **latest stable** patch releases and
-  has to be used for Backward Compatible bug fixes only.
   * Branch `3.x` is the branch of the **latest stable** minor release and
-  has to be used for Backward compatible enhancement PRs.
-  **No bug fix will be accepted here**, except if the bug fix concerns `3.x` and **only this one**.
-  Bug fixes merged on `3.x` will be ported on other branches by fallback merging.
+  has to be used for Backward compatible PRs.
   * If you PR is not **Backward Compatible** but can be, it **must** be:
     * Changing a function/method signature? Prefer create a new one and deprecate the old one.
     * Code deletion? Don't. Please deprecate it instead.
@@ -237,8 +232,62 @@ interface BarInterface
 }
 ```
 
-In some cases, you will have the possibility to warn the user that things will change,
-and recommend a new way of doing things. You can do so by triggering the dedicated kind of error, like this:
+##### Deprecation
+
+In some cases, you might have some code parts that might become superseded by others, but could still be used by the end user.
+If the concerned code is not tagged as `internal`, it must be deprecated on the stable branch, then removed.
+
+If an alternate usage solution is possible, you **MUST** provide it in the deprecation message.
+
+The deprecated minor version **MUST NOT** be provided. Use `x` instead. It will be updated when releasing.
+
+Any deprecation **MUST** be documented in the corresponding `UPGRADE-[0-9].x.md`.
+The documentation **MUST** be filled inside the top **unreleased** section with a sub title.
+
+The `NEXT_MAJOR` tag should not be used for deprecation.
+The `@deprecated` and `E_USER_DEPRECATED` key will be searched for before releasing the next major version.
+
+You have three ways to deprecate things.
+
+For class definitions, methods (or first level functions) and properties, use the `@deprecated` tag: 
+
+```php
+/**
+ * @deprecated since 42.x, to be removed in 43.0. Use Shiny\New\ClassOfTheMonth instead.
+ */
+final class IAmOldAndUseless
+{
+}
+
+final class StillUsedClass
+{
+    /**
+     * @deprecated since 42.x, to be removed in 43.0.
+     */
+    public $butNotThisProperty;
+
+    /**
+     * @deprecated since 42.x, to be removed in 43.0.
+     */
+    public function iAmBatman()
+    {
+        echo "But this is not Gotham here.";
+    }
+}
+```
+
+If the deprecated thing is a service, you **MUST** specify it on the service definition:
+
+```xml
+<service id="sonata.block.old" class="Sonata\Block\Old">
+    <argument type="service" id="security.token_storage" />
+    <deprecated>The "%service_id%" service is deprecated since 42.x and will be removed in 43.0.</deprecated>
+ </service>
+ ```
+
+More info: http://symfony.com/blog/new-in-symfony-2-8-deprecated-service-definitions
+
+For everything else, not managed by the `@deprecated` tag, you **MUST** trigger a deprecation message.
 
 ```php
 <?php
@@ -253,29 +302,40 @@ if (/* some condition showing the user is using the legacy way */) {
 }
 ```
 
-Additionally, and when applicable, you must use the `@deprecated` tag on classes or methods you wish to deprecate,
-along with a message directed at the end user (as opposed to other contributors).
-
-
-```php
-/**
- * NEXT_MAJOR: remove this method
- *
- * @deprecated since 3.x, to be removed in 4.0. Use Foo::bar instead.
- */
-public function baz()
-{
-}
-```
+Note that the `trigger_error` usage is not necessary if the `@deprecated` tag is used.
 
-In that case, unit tests might show your deprecation notice. You must mark such tests with the `@group legacy` annotation,
-and if need be, isolate them in a new test method that can simply be removed in the non-BC PR.
+In the case of a deprecation, unit tests might show your deprecation notice.
+You **MUST** mark such tests with the `@group legacy` annotation and if need be,
+isolate them in a new test method that can simply be removed in the non-BC PR.
 
 Be aware that pull requests with BC breaks could be rejected
-or postponed to next major release if BC is not possible.
+or postponed to next major release **only** if BC is not possible.
 
 If you are not sure what should be done, don't hesitate to open an issue about your PR project.
 
+##### Dependency changes
+
+If you want to change some dependencies, here are the rules:
+
+- Don't add support for a version lower than the current one.
+- Don't change the highest supported version to a lower one.
+- Lower version dropping is accepted as a Backward Compatible change according to [semver][semver_dependencies_update],
+but some extra rules must be respected here:
+  - PHP versions that are under the [orange zone][php_supported_versions] (Security Support) **MUST NOT** be dropped on the stable branch.
+  - PHP versions that are under the [green zone][php_supported_versions] (Active Support) **MUST NOT** be dropped on the master branch.
+  - If it's a Symfony package, at least the last LTS version **MUST** be supported, even on master.
+  - Generally, don't drop dependency version it it doesn't have a big impact on the code.
+  - Backward Compatible code related to the dropped version **MUST** be dropped on the same PR.
+    This will allow to see if this version drop **is really worth it** or not.
+    Please note that we can refuse a version drop at any moment if the gain does not seem sufficient.
+
+##### Legacy branches
+
+Legacy branches are **NOT** supported at all. Any submitted Pull Request will be immediately closed.
+
+Core team members *may* cherry-pick some fixes from the stable branch to the legacy one if it's really needed
+and if the legacy one is not too old (~less than one month).
+
 #### The commit message
 
 Sonata is a big project with many contributors, and a big part of the job is
@@ -421,6 +481,17 @@ use the "Rebase and merge" feature.
 And finally, use your common sense : if you see a PR about a typo,
 or if there is a situation (faulty commit, revert needed) maybe you can merge it directly.
 
+#### Dependencies version dropping
+
+Do not merge any merge request dropping a dependency version support.
+To achieve that, mark them as `RTM`, and mention then on Slack when asking for a release.
+
+This rule should be applied for these reasons:
+
+- Even if it's semver compatible, we don't maintain minor branches.
+So it's preferable to give priority to bugfixes over version-dropping PRs.
+- Some dependencies need a dev-kit update. By the way, you can make a PR on dev-kit and link it to your own.
+
 ### Be nice to the contributor
 
 Thank them for contributing. Encourage them if you feel this is going to be long.
@@ -430,3 +501,5 @@ code yourself, or ping someone who can help.
 [sphinx_install]: http://www.sphinx-doc.org/en/stable/
 [pip_install]: https://pip.pypa.io/en/stable/installing/
 [sf_docs_standards]: https://symfony.com/doc/current/contributing/documentation/standards.html
+[semver_dependencies_update]: http://semver.org/#what-should-i-do-if-i-update-my-own-dependencies-without-changing-the-public-api
+[php_supported_versions]: http://php.net/supported-versions.php
diff --git a/Datagrid/ProxyQuery.php b/Datagrid/ProxyQuery.php
index 837f32c1..2b68a4fb 100644
--- a/Datagrid/ProxyQuery.php
+++ b/Datagrid/ProxyQuery.php
@@ -35,7 +35,7 @@ public function __construct(Builder $queryBuilder)
 
     public function __call($name, $args)
     {
-        return call_user_func_array(array($this->queryBuilder, $name), $args);
+        return call_user_func_array([$this->queryBuilder, $name], $args);
     }
 
     public function __clone()
@@ -49,7 +49,7 @@ public function __clone()
      *
      * @return mixed
      */
-    public function execute(array $params = array(), $hydrationMode = null)
+    public function execute(array $params = [], $hydrationMode = null)
     {
         // always clone the original queryBuilder.
         $queryBuilder = clone $this->queryBuilder;
diff --git a/DependencyInjection/Compiler/AddGuesserCompilerPass.php b/DependencyInjection/Compiler/AddGuesserCompilerPass.php
index 0a5edaa5..490c081d 100644
--- a/DependencyInjection/Compiler/AddGuesserCompilerPass.php
+++ b/DependencyInjection/Compiler/AddGuesserCompilerPass.php
@@ -27,7 +27,7 @@ public function process(ContainerBuilder $container)
     {
         // ListBuilder
         $definition = $container->getDefinition('sonata.admin.guesser.doctrine_mongodb_list_chain');
-        $services = array();
+        $services = [];
         foreach ($container->findTaggedServiceIds('sonata.admin.guesser.doctrine_mongodb_list') as $id => $attributes) {
             $services[] = new Reference($id);
         }
@@ -36,7 +36,7 @@ public function process(ContainerBuilder $container)
 
         // DatagridBuilder
         $definition = $container->getDefinition('sonata.admin.guesser.doctrine_mongodb_datagrid_chain');
-        $services = array();
+        $services = [];
         foreach ($container->findTaggedServiceIds('sonata.admin.guesser.doctrine_mongodb_datagrid') as $id => $attributes) {
             $services[] = new Reference($id);
         }
@@ -45,7 +45,7 @@ public function process(ContainerBuilder $container)
 
         // ShowBuilder
         $definition = $container->getDefinition('sonata.admin.guesser.doctrine_mongodb_show_chain');
-        $services = array();
+        $services = [];
         foreach ($container->findTaggedServiceIds('sonata.admin.guesser.doctrine_mongodb_show') as $id => $attributes) {
             $services[] = new Reference($id);
         }
diff --git a/DependencyInjection/Compiler/AddTemplatesCompilerPass.php b/DependencyInjection/Compiler/AddTemplatesCompilerPass.php
index 4b6e96b0..7d4f8ac6 100644
--- a/DependencyInjection/Compiler/AddTemplatesCompilerPass.php
+++ b/DependencyInjection/Compiler/AddTemplatesCompilerPass.php
@@ -33,11 +33,11 @@ public function process(ContainerBuilder $container)
             $templates = $container->getParameter('sonata_doctrine_mongodb_admin.templates');
 
             if (!$definition->hasMethodCall('setFormTheme')) {
-                $definition->addMethodCall('setFormTheme', array($templates['form']));
+                $definition->addMethodCall('setFormTheme', [$templates['form']]);
             }
 
             if (!$definition->hasMethodCall('setFilterTheme')) {
-                $definition->addMethodCall('setFilterTheme', array($templates['filter']));
+                $definition->addMethodCall('setFilterTheme', [$templates['filter']]);
             }
         }
     }
diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 71810cc2..915c0a2f 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -41,11 +41,11 @@ public function getConfigTreeBuilder()
                     ->children()
                         ->arrayNode('form')
                             ->prototype('scalar')->end()
-                            ->defaultValue(array('SonataDoctrineMongoDBAdminBundle:Form:form_admin_fields.html.twig'))
+                            ->defaultValue(['SonataDoctrineMongoDBAdminBundle:Form:form_admin_fields.html.twig'])
                         ->end()
                         ->arrayNode('filter')
                             ->prototype('scalar')->end()
-                            ->defaultValue(array('SonataDoctrineMongoDBAdminBundle:Form:filter_admin_fields.html.twig'))
+                            ->defaultValue(['SonataDoctrineMongoDBAdminBundle:Form:filter_admin_fields.html.twig'])
                         ->end()
                         ->arrayNode('types')
                             ->children()
diff --git a/Filter/AbstractDateFilter.php b/Filter/AbstractDateFilter.php
index 41e431ba..d97f295b 100644
--- a/Filter/AbstractDateFilter.php
+++ b/Filter/AbstractDateFilter.php
@@ -81,7 +81,7 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array('input_type' => 'datetime');
+        return ['input_type' => 'datetime'];
     }
 
     /**
@@ -99,11 +99,11 @@ public function getRenderSettings()
             $name .= '_range';
         }
 
-        return array($name, array(
+        return [$name, [
                 'field_type' => $this->getFieldType(),
                 'field_options' => $this->getFieldOptions(),
                 'label' => $this->getLabel(),
-        ));
+        ]];
     }
 
     /**
@@ -127,9 +127,9 @@ protected function applyType(ProxyQueryInterface $queryBuilder, $operation, $fie
      */
     protected function typeRequiresValue($type)
     {
-        return in_array($type, array(
+        return in_array($type, [
                     DateType::TYPE_NULL,
-                    DateType::TYPE_NOT_NULL, )
+                    DateType::TYPE_NOT_NULL, ]
         );
     }
 
@@ -142,7 +142,7 @@ protected function typeRequiresValue($type)
      */
     protected function getOperator($type)
     {
-        $choices = array(
+        $choices = [
             DateType::TYPE_NULL => 'equals',
             DateType::TYPE_NOT_NULL => 'notEqual',
             DateType::TYPE_EQUAL => 'equals',
@@ -150,7 +150,7 @@ protected function getOperator($type)
             DateType::TYPE_GREATER_THAN => 'gt',
             DateType::TYPE_LESS_EQUAL => 'lte',
             DateType::TYPE_LESS_THAN => 'lt',
-        );
+        ];
 
         return $choices[intval($type)];
     }
diff --git a/Filter/BooleanFilter.php b/Filter/BooleanFilter.php
index 8cec54b6..ec54dc26 100644
--- a/Filter/BooleanFilter.php
+++ b/Filter/BooleanFilter.php
@@ -29,9 +29,9 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
         }
 
         if (is_array($data['value'])) {
-            $values = array();
+            $values = [];
             foreach ($data['value'] as $v) {
-                if (!in_array($v, array(BooleanType::TYPE_NO, BooleanType::TYPE_YES))) {
+                if (!in_array($v, [BooleanType::TYPE_NO, BooleanType::TYPE_YES])) {
                     continue;
                 }
 
@@ -45,7 +45,7 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
             $queryBuilder->field($field)->in($values);
             $this->active = true;
         } else {
-            if (!in_array($data['value'], array(BooleanType::TYPE_NO, BooleanType::TYPE_YES))) {
+            if (!in_array($data['value'], [BooleanType::TYPE_NO, BooleanType::TYPE_YES])) {
                 return;
             }
 
@@ -61,17 +61,17 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array();
+        return [];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_default', array(
+        return ['sonata_type_filter_default', [
             'field_type' => $this->getFieldType(),
             'field_options' => $this->getFieldOptions(),
             'operator_type' => 'hidden',
-            'operator_options' => array(),
+            'operator_options' => [],
             'label' => $this->getLabel(),
-        ));
+        ]];
     }
 }
diff --git a/Filter/CallbackFilter.php b/Filter/CallbackFilter.php
index f08b84fc..6911f1c3 100644
--- a/Filter/CallbackFilter.php
+++ b/Filter/CallbackFilter.php
@@ -48,25 +48,25 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array(
+        return [
             'callback' => null,
             'active_callback' => function ($data) {
                 return isset($data['value']) && $data['value'];
             },
             'field_type' => 'text',
             'operator_type' => 'hidden',
-            'operator_options' => array(),
-        );
+            'operator_options' => [],
+        ];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_default', array(
+        return ['sonata_type_filter_default', [
                 'field_type' => $this->getFieldType(),
                 'field_options' => $this->getFieldOptions(),
                 'operator_type' => $this->getOption('operator_type'),
                 'operator_options' => $this->getOption('operator_options'),
                 'label' => $this->getLabel(),
-        ));
+        ]];
     }
 }
diff --git a/Filter/ChoiceFilter.php b/Filter/ChoiceFilter.php
index b05c2b2c..ce6401e3 100644
--- a/Filter/ChoiceFilter.php
+++ b/Filter/ChoiceFilter.php
@@ -64,16 +64,16 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array();
+        return [];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_default', array(
+        return ['sonata_type_filter_default', [
                 'operator_type' => 'sonata_type_boolean',
                 'field_type' => $this->getFieldType(),
                 'field_options' => $this->getFieldOptions(),
                 'label' => $this->getLabel(),
-        ));
+        ]];
     }
 }
diff --git a/Filter/ModelFilter.php b/Filter/ModelFilter.php
index ba6251e9..79487ffc 100644
--- a/Filter/ModelFilter.php
+++ b/Filter/ModelFilter.php
@@ -44,25 +44,25 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
 
     public function getDefaultOptions()
     {
-        return array(
+        return [
             'mapping_type' => false,
             'field_name' => false,
             'field_type' => 'document',
-            'field_options' => array(),
+            'field_options' => [],
             'operator_type' => 'sonata_type_equal',
-            'operator_options' => array(),
-        );
+            'operator_options' => [],
+        ];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_default', array(
+        return ['sonata_type_filter_default', [
             'field_type' => $this->getFieldType(),
             'field_options' => $this->getFieldOptions(),
             'operator_type' => $this->getOption('operator_type'),
             'operator_options' => $this->getOption('operator_options'),
             'label' => $this->getLabel(),
-        ));
+        ]];
     }
 
     /**
@@ -79,7 +79,7 @@ protected function handleMultiple(ProxyQueryInterface $queryBuilder, $alias, $fi
             return;
         }
 
-        $ids = array();
+        $ids = [];
         foreach ($data['value'] as $value) {
             $ids[] = self::fixIdentifier($value->getId());
         }
diff --git a/Filter/NumberFilter.php b/Filter/NumberFilter.php
index 9ee59075..587ae3c7 100644
--- a/Filter/NumberFilter.php
+++ b/Filter/NumberFilter.php
@@ -45,16 +45,16 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array();
+        return [];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_number', array(
+        return ['sonata_type_filter_number', [
             'field_type' => $this->getFieldType(),
             'field_options' => $this->getFieldOptions(),
             'label' => $this->getLabel(),
-        ));
+        ]];
     }
 
     /**
@@ -64,13 +64,13 @@ public function getRenderSettings()
      */
     private function getOperator($type)
     {
-        $choices = array(
+        $choices = [
             NumberType::TYPE_EQUAL => 'equals',
             NumberType::TYPE_GREATER_EQUAL => 'gte',
             NumberType::TYPE_GREATER_THAN => 'gt',
             NumberType::TYPE_LESS_EQUAL => 'lte',
             NumberType::TYPE_LESS_THAN => 'lt',
-        );
+        ];
 
         return isset($choices[$type]) ? $choices[$type] : false;
     }
diff --git a/Filter/StringFilter.php b/Filter/StringFilter.php
index 091bff19..86031974 100644
--- a/Filter/StringFilter.php
+++ b/Filter/StringFilter.php
@@ -61,15 +61,15 @@ public function filter(ProxyQueryInterface $queryBuilder, $name, $field, $data)
      */
     public function getDefaultOptions()
     {
-        return array();
+        return [];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_choice', array(
+        return ['sonata_type_filter_choice', [
                 'field_type' => $this->getFieldType(),
                 'field_options' => $this->getFieldOptions(),
                 'label' => $this->getLabel(),
-        ));
+        ]];
     }
 }
diff --git a/Guesser/FilterTypeGuesser.php b/Guesser/FilterTypeGuesser.php
index a6426430..6aad0a70 100644
--- a/Guesser/FilterTypeGuesser.php
+++ b/Guesser/FilterTypeGuesser.php
@@ -28,11 +28,11 @@ public function guessType($class, $property, ModelManagerInterface $modelManager
             return false;
         }
 
-        $options = array(
+        $options = [
             'field_type' => null,
-            'field_options' => array(),
-            'options' => array(),
-        );
+            'field_options' => [],
+            'options' => [],
+        ];
 
         list($metadata, $propertyName, $parentAssociationMappings) = $ret;
 
@@ -48,12 +48,12 @@ public function guessType($class, $property, ModelManagerInterface $modelManager
                     //case ClassMetadataInfo::MANY_TO_MANY:
 
                     $options['operator_type'] = 'sonata_type_equal';
-                    $options['operator_options'] = array();
+                    $options['operator_options'] = [];
 
                     $options['field_type'] = 'document';
-                    $options['field_options'] = array(
+                    $options['field_options'] = [
                         'class' => $mapping['targetDocument'],
-                    );
+                    ];
 
                     $options['field_name'] = $mapping['fieldName'];
                     $options['mapping_type'] = $mapping['type'];
@@ -71,7 +71,7 @@ public function guessType($class, $property, ModelManagerInterface $modelManager
         switch ($metadata->getTypeOfField($propertyName)) {
             case 'boolean':
                 $options['field_type'] = 'sonata_type_boolean';
-                $options['field_options'] = array();
+                $options['field_options'] = [];
 
                 return new TypeGuess('doctrine_mongo_boolean', $options, Guess::HIGH_CONFIDENCE);
 //            case 'datetime':
diff --git a/Guesser/TypeGuesser.php b/Guesser/TypeGuesser.php
index 4d36d87b..a9a27601 100755
--- a/Guesser/TypeGuesser.php
+++ b/Guesser/TypeGuesser.php
@@ -24,7 +24,7 @@ class TypeGuesser extends AbstractTypeGuesser
     public function guessType($class, $property, ModelManagerInterface $modelManager)
     {
         if (!$ret = $this->getParentMetadataForProperty($class, $property, $modelManager)) {
-            return new TypeGuess('text', array(), Guess::LOW_CONFIDENCE);
+            return new TypeGuess('text', [], Guess::LOW_CONFIDENCE);
         }
 
         list($metadata, $propertyName, $parentAssociationMappings) = $ret;
@@ -34,10 +34,10 @@ public function guessType($class, $property, ModelManagerInterface $modelManager
 
             switch ($mapping['type']) {
                 case ClassMetadataInfo::ONE:
-                    return new TypeGuess('mongo_one', array(), Guess::HIGH_CONFIDENCE);
+                    return new TypeGuess('mongo_one', [], Guess::HIGH_CONFIDENCE);
 
                 case ClassMetadataInfo::MANY:
-                    return new TypeGuess('mongo_many', array(), Guess::HIGH_CONFIDENCE);
+                    return new TypeGuess('mongo_many', [], Guess::HIGH_CONFIDENCE);
             }
         }
 
@@ -45,31 +45,31 @@ public function guessType($class, $property, ModelManagerInterface $modelManager
             case 'collection':
             case 'hash':
             case 'array':
-              return new TypeGuess('array', array(), Guess::HIGH_CONFIDENCE);
+              return new TypeGuess('array', [], Guess::HIGH_CONFIDENCE);
             case 'boolean':
-                return new TypeGuess('boolean', array(), Guess::HIGH_CONFIDENCE);
+                return new TypeGuess('boolean', [], Guess::HIGH_CONFIDENCE);
             case 'datetime':
             case 'vardatetime':
             case 'datetimetz':
             case 'timestamp':
-                return new TypeGuess('datetime', array(), Guess::HIGH_CONFIDENCE);
+                return new TypeGuess('datetime', [], Guess::HIGH_CONFIDENCE);
             case 'date':
-                return new TypeGuess('date', array(), Guess::HIGH_CONFIDENCE);
+                return new TypeGuess('date', [], Guess::HIGH_CONFIDENCE);
             case 'decimal':
             case 'float':
-                return new TypeGuess('number', array(), Guess::MEDIUM_CONFIDENCE);
+                return new TypeGuess('number', [], Guess::MEDIUM_CONFIDENCE);
             case 'integer':
             case 'bigint':
             case 'smallint':
-                return new TypeGuess('integer', array(), Guess::MEDIUM_CONFIDENCE);
+                return new TypeGuess('integer', [], Guess::MEDIUM_CONFIDENCE);
             case 'string':
-                return new TypeGuess('text', array(), Guess::MEDIUM_CONFIDENCE);
+                return new TypeGuess('text', [], Guess::MEDIUM_CONFIDENCE);
             case 'text':
-                return new TypeGuess('textarea', array(), Guess::MEDIUM_CONFIDENCE);
+                return new TypeGuess('textarea', [], Guess::MEDIUM_CONFIDENCE);
             case 'time':
-                return new TypeGuess('time', array(), Guess::HIGH_CONFIDENCE);
+                return new TypeGuess('time', [], Guess::HIGH_CONFIDENCE);
             default:
-                return new TypeGuess('text', array(), Guess::LOW_CONFIDENCE);
+                return new TypeGuess('text', [], Guess::LOW_CONFIDENCE);
         }
     }
 }
diff --git a/Model/ModelManager.php b/Model/ModelManager.php
index 929eddef..45570422 100755
--- a/Model/ModelManager.php
+++ b/Model/ModelManager.php
@@ -62,7 +62,7 @@ public function getParentMetadataForProperty($baseClass, $propertyFullName)
         $nameElements = explode('.', $propertyFullName);
         $lastPropertyName = array_pop($nameElements);
         $class = $baseClass;
-        $parentAssociationMappings = array();
+        $parentAssociationMappings = [];
 
         foreach ($nameElements as $nameElement) {
             $metadata = $this->getMetadata($class);
@@ -70,7 +70,7 @@ public function getParentMetadataForProperty($baseClass, $propertyFullName)
             $class = $metadata->getAssociationTargetClass($nameElement);
         }
 
-        return array($this->getMetadata($class), $lastPropertyName, $parentAssociationMappings);
+        return [$this->getMetadata($class), $lastPropertyName, $parentAssociationMappings];
     }
 
     /**
@@ -84,7 +84,7 @@ public function hasMetadata($class)
     /**
      * {@inheritdoc}
      */
-    public function getNewFieldDescriptionInstance($class, $name, array $options = array())
+    public function getNewFieldDescriptionInstance($class, $name, array $options = [])
     {
         if (!is_string($name)) {
             throw new \RunTimeException('The name argument must be a string');
@@ -95,7 +95,7 @@ public function getNewFieldDescriptionInstance($class, $name, array $options = a
         }
 
         if (!isset($options['route']['parameters'])) {
-            $options['route']['parameters'] = array();
+            $options['route']['parameters'] = [];
         }
 
         list($metadata, $propertyName, $parentAssociationMappings) = $this->getParentMetadataForProperty($class, $name);
@@ -172,7 +172,7 @@ public function find($class, $id)
     /**
      * {@inheritdoc}
      */
-    public function findBy($class, array $criteria = array())
+    public function findBy($class, array $criteria = [])
     {
         return $this->getDocumentManager($class)->getRepository($class)->findBy($criteria);
     }
@@ -180,7 +180,7 @@ public function findBy($class, array $criteria = array())
     /**
      * {@inheritdoc}
      */
-    public function findOneBy($class, array $criteria = array())
+    public function findOneBy($class, array $criteria = [])
     {
         return $this->getDocumentManager($class)->getRepository($class)->findOneBy($criteria);
     }
@@ -260,7 +260,7 @@ public function getModelIdentifier($class)
      */
     public function getIdentifierValues($document)
     {
-        return array($this->getDocumentManager($document)->getUnitOfWork()->getDocumentIdentifier($document));
+        return [$this->getDocumentManager($document)->getUnitOfWork()->getDocumentIdentifier($document)];
     }
 
     /**
@@ -268,7 +268,7 @@ public function getIdentifierValues($document)
      */
     public function getIdentifierFieldNames($class)
     {
-        return array($this->getMetadata($class)->getIdentifier());
+        return [$this->getMetadata($class)->getIdentifier()];
     }
 
     /**
@@ -382,7 +382,7 @@ public function getSortParameters(FieldDescriptionInterface $fieldDescription, D
 
         $values['_sort_by'] = is_string($fieldDescription->getOption('sortable')) ? $fieldDescription->getOption('sortable') : $fieldDescription->getName();
 
-        return array('filter' => $values);
+        return ['filter' => $values];
     }
 
     /**
@@ -395,7 +395,7 @@ public function getPaginationParameters(DatagridInterface $datagrid, $page)
         $values['_sort_by'] = $values['_sort_by']->getName();
         $values['_page'] = $page;
 
-        return array('filter' => $values);
+        return ['filter' => $values];
     }
 
     /**
@@ -403,12 +403,12 @@ public function getPaginationParameters(DatagridInterface $datagrid, $page)
      */
     public function getDefaultSortValues($class)
     {
-        return array(
+        return [
             '_sort_order' => 'ASC',
             '_sort_by' => $this->getModelIdentifier($class),
             '_page' => 1,
             '_per_page' => 25,
-        );
+        ];
     }
 
     /**
@@ -422,7 +422,7 @@ public function modelTransform($class, $instance)
     /**
      * {@inheritdoc}
      */
-    public function modelReverseTransform($class, array $array = array())
+    public function modelReverseTransform($class, array $array = [])
     {
         $instance = $this->getModelInstance($class);
         $metadata = $this->getMetadata($class);
@@ -514,6 +514,6 @@ public function collectionRemoveElement(&$collection, &$element)
      */
     protected function camelize($property)
     {
-        return preg_replace(array('/(^|_)+(.)/e', '/\.(.)/e'), array("strtoupper('\\2')", "'_'.strtoupper('\\1')"), $property);
+        return preg_replace(['/(^|_)+(.)/e', '/\.(.)/e'], ["strtoupper('\\2')", "'_'.strtoupper('\\1')"], $property);
     }
 }
diff --git a/README.md b/README.md
index 0fdcb9ff..6c7774b9 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,6 @@ Symfony Sonata / Integrate Doctrine MongoDB ODM into the SonataAdminBundle
 
 Branch | Travis | Coveralls |
 ------ | ------ | --------- |
-3.x   | [![Build Status][travis_legacy_badge]][travis_legacy_link]     | [![Coverage Status][coveralls_legacy_badge]][coveralls_legacy_link]     |
 3.x   | [![Build Status][travis_stable_badge]][travis_stable_link]     | [![Coverage Status][coveralls_stable_badge]][coveralls_stable_link]     |
 master | [![Build Status][travis_unstable_badge]][travis_unstable_link] | [![Coverage Status][coveralls_unstable_badge]][coveralls_unstable_link] |
 
@@ -31,15 +30,11 @@ If you think you found a bug or you have a feature idea to propose, feel free to
 
 This package is available under the [MIT license](LICENSE).
 
-[travis_legacy_badge]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle.svg?branch=3.x
-[travis_legacy_link]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle
 [travis_stable_badge]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle.svg?branch=3.x
 [travis_stable_link]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle
 [travis_unstable_badge]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle.svg?branch=master
 [travis_unstable_link]: https://travis-ci.org/sonata-project/SonataDoctrineMongoDBAdminBundle
 
-[coveralls_legacy_badge]: https://coveralls.io/repos/github/sonata-project/SonataDoctrineMongoDBAdminBundle/badge.svg?branch=3.x
-[coveralls_legacy_link]: https://coveralls.io/github/sonata-project/SonataDoctrineMongoDBAdminBundle?branch=3.x
 [coveralls_stable_badge]: https://coveralls.io/repos/github/sonata-project/SonataDoctrineMongoDBAdminBundle/badge.svg?branch=3.x
 [coveralls_stable_link]: https://coveralls.io/github/sonata-project/SonataDoctrineMongoDBAdminBundle?branch=3.x
 [coveralls_unstable_badge]: https://coveralls.io/repos/github/sonata-project/SonataDoctrineMongoDBAdminBundle/badge.svg?branch=master
diff --git a/Tests/Admin/FieldDescriptionTest.php b/Tests/Admin/FieldDescriptionTest.php
index a9496876..80d7320f 100644
--- a/Tests/Admin/FieldDescriptionTest.php
+++ b/Tests/Admin/FieldDescriptionTest.php
@@ -11,19 +11,19 @@
 
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Admin;
 
+use PHPUnit\Framework\TestCase;
 use Sonata\DoctrineMongoDBAdminBundle\Admin\FieldDescription;
-use Sonata\DoctrineMongoDBAdminBundle\Tests\Helpers\PHPUnit_Framework_TestCase;
 
-class FieldDescriptionTest extends PHPUnit_Framework_TestCase
+class FieldDescriptionTest extends TestCase
 {
     public function testOptions()
     {
         $field = new FieldDescription();
-        $field->setOptions(array(
+        $field->setOptions([
             'template' => 'foo',
             'type' => 'bar',
             'misc' => 'foobar',
-        ));
+        ]);
 
         // test method shortcut
         $this->assertEquals(null, $field->getOption('template'));
@@ -36,45 +36,45 @@ public function testOptions()
         $this->assertEquals('default', $field->getOption('template', 'default'));
 
         // test the merge options
-        $field->setOption('array', array('key1' => 'val1'));
-        $field->mergeOption('array', array('key1' => 'key_1', 'key2' => 'key_2'));
+        $field->setOption('array', ['key1' => 'val1']);
+        $field->mergeOption('array', ['key1' => 'key_1', 'key2' => 'key_2']);
 
-        $this->assertEquals(array('key1' => 'key_1', 'key2' => 'key_2'), $field->getOption('array'));
+        $this->assertEquals(['key1' => 'key_1', 'key2' => 'key_2'], $field->getOption('array'));
 
-        $field->mergeOption('non_existant', array('key1' => 'key_1', 'key2' => 'key_2'));
+        $field->mergeOption('non_existant', ['key1' => 'key_1', 'key2' => 'key_2']);
 
-        $this->assertEquals(array('key1' => 'key_1', 'key2' => 'key_2'), $field->getOption('array'));
+        $this->assertEquals(['key1' => 'key_1', 'key2' => 'key_2'], $field->getOption('array'));
 
-        $field->mergeOptions(array('array' => array('key3' => 'key_3')));
+        $field->mergeOptions(['array' => ['key3' => 'key_3']]);
 
-        $this->assertEquals(array('key1' => 'key_1', 'key2' => 'key_2', 'key3' => 'key_3'), $field->getOption('array'));
+        $this->assertEquals(['key1' => 'key_1', 'key2' => 'key_2', 'key3' => 'key_3'], $field->getOption('array'));
 
         $field->setOption('integer', 1);
 
         try {
-            $field->mergeOption('integer', array());
+            $field->mergeOption('integer', []);
             $this->fail('no exception raised !!');
         } catch (\RuntimeException $e) {
         }
 
-        $field->mergeOptions(array('final' => 'test'));
+        $field->mergeOptions(['final' => 'test']);
 
-        $expected = array(
+        $expected = [
           'misc' => 'foobar',
           'placeholder' => 'short_object_description_placeholder',
-          'array' => array(
+          'array' => [
             'key1' => 'key_1',
             'key2' => 'key_2',
             'key3' => 'key_3',
-          ),
-          'non_existant' => array(
+          ],
+          'non_existant' => [
             'key1' => 'key_1',
             'key2' => 'key_2',
-          ),
+          ],
           'integer' => 1,
           'final' => 'test',
-          'link_parameters' => array(),
-        );
+          'link_parameters' => [],
+        ];
 
         $this->assertEquals($expected, $field->getOptions());
     }
@@ -82,19 +82,19 @@ public function testOptions()
     public function testAssociationMapping()
     {
         $field = new FieldDescription();
-        $field->setAssociationMapping(array(
+        $field->setAssociationMapping([
             'type' => 'integer',
             'fieldName' => 'position',
-        ));
+        ]);
 
         $this->assertEquals('integer', $field->getType());
         $this->assertEquals('position', $field->getFieldName());
 
         // cannot overwrite defined definition
-        $field->setAssociationMapping(array(
+        $field->setAssociationMapping([
             'type' => 'overwrite?',
             'fieldName' => 'overwritten',
-        ));
+        ]);
 
         $this->assertEquals('integer', $field->getType());
         $this->assertEquals('overwritten', $field->getFieldName());
@@ -194,7 +194,7 @@ public function testHasAssociationAdmin()
     public function testGetValue()
     {
         $mockedObject = $this->getMockBuilder('MockedTestObject')
-            ->setMethods(array('myMethod'))
+            ->setMethods(['myMethod'])
             ->getMock();
         $mockedObject->expects($this->once())
             ->method('myMethod')
@@ -212,7 +212,7 @@ public function testGetValue()
     public function testGetValueWhenCannotRetrieve()
     {
         $mockedObject = $this->getMockBuilder('MockedTestObject')
-            ->setMethods(array('myMethod'))
+            ->setMethods(['myMethod'])
             ->getMock();
         $mockedObject->expects($this->never())
             ->method('myMethod')
@@ -225,10 +225,10 @@ public function testGetValueWhenCannotRetrieve()
 
     public function testGetAssociationMapping()
     {
-        $assocationMapping = array(
+        $assocationMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setAssociationMapping($assocationMapping);
@@ -256,10 +256,10 @@ public function testSetFieldMappingAllowOnlyForArray()
 
     public function testSetFieldMappingSetType()
     {
-        $fieldMapping = array(
+        $fieldMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setFieldMapping($fieldMapping);
@@ -269,10 +269,10 @@ public function testSetFieldMappingSetType()
 
     public function testSetFieldMappingSetMappingType()
     {
-        $fieldMapping = array(
+        $fieldMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setFieldMapping($fieldMapping);
@@ -282,10 +282,10 @@ public function testSetFieldMappingSetMappingType()
 
     public function testSetFieldMappingSetFieldName()
     {
-        $fieldMapping = array(
+        $fieldMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setFieldMapping($fieldMapping);
@@ -295,11 +295,11 @@ public function testSetFieldMappingSetFieldName()
 
     public function testGetTargetEntity()
     {
-        $assocationMapping = array(
+        $assocationMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
             'targetDocument' => 'someValue',
-        );
+        ];
 
         $field = new FieldDescription();
 
@@ -312,11 +312,11 @@ public function testGetTargetEntity()
 
     public function testIsIdentifierFromFieldMapping()
     {
-        $fieldMapping = array(
+        $fieldMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
             'id' => 'someId',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setFieldMapping($fieldMapping);
@@ -326,11 +326,11 @@ public function testIsIdentifierFromFieldMapping()
 
     public function testGetFieldMapping()
     {
-        $fieldMapping = array(
+        $fieldMapping = [
             'type' => 'integer',
             'fieldName' => 'position',
             'id' => 'someId',
-        );
+        ];
 
         $field = new FieldDescription();
         $field->setFieldMapping($fieldMapping);
diff --git a/Tests/Builder/FormContractorTest.php b/Tests/Builder/FormContractorTest.php
index 1e246d64..839eb4c1 100644
--- a/Tests/Builder/FormContractorTest.php
+++ b/Tests/Builder/FormContractorTest.php
@@ -12,11 +12,11 @@
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Builder;
 
 use Doctrine\ODM\MongoDB\Mapping\ClassMetadataInfo;
+use PHPUnit\Framework\TestCase;
 use Sonata\DoctrineMongoDBAdminBundle\Builder\FormContractor;
-use Sonata\DoctrineMongoDBAdminBundle\Tests\Helpers\PHPUnit_Framework_TestCase;
 use Symfony\Component\Form\FormFactoryInterface;
 
-class FormContractorTest extends PHPUnit_Framework_TestCase
+class FormContractorTest extends TestCase
 {
     /**
      * @var FormFactoryInterface|\PHPUnit_Framework_MockObject_MockObject
@@ -30,17 +30,17 @@ class FormContractorTest extends PHPUnit_Framework_TestCase
 
     protected function setUp()
     {
-        $this->formFactory = $this->getMock('Symfony\Component\Form\FormFactoryInterface');
+        $this->formFactory = $this->createMock('Symfony\Component\Form\FormFactoryInterface');
         $this->formContractor = new FormContractor($this->formFactory);
     }
 
     public function testGetFormBuilder()
     {
         $this->formFactory->expects($this->once())->method('createNamedBuilder')
-            ->willReturn($this->getMock('Symfony\Component\Form\FormBuilderInterface'));
+            ->willReturn($this->createMock('Symfony\Component\Form\FormBuilderInterface'));
         $this->assertInstanceOf(
             'Symfony\Component\Form\FormBuilderInterface',
-            $this->formContractor->getFormBuilder('test', array('foo' => 'bar'))
+            $this->formContractor->getFormBuilder('test', ['foo' => 'bar'])
         );
     }
 
@@ -55,18 +55,18 @@ public function testDefaultOptionsForSonataFormTypes()
         $fieldDescription->method('getAdmin')->willReturn($admin);
         $fieldDescription->method('getTargetEntity')->willReturn($modelClass);
         $fieldDescription->method('getAssociationAdmin')->willReturn($admin);
-        $modelTypes = array(
+        $modelTypes = [
             'sonata_type_model',
             'sonata_type_model_list',
-        );
-        $adminTypes = array('sonata_type_admin');
-        $collectionTypes = array('sonata_type_collection');
+        ];
+        $adminTypes = ['sonata_type_admin'];
+        $collectionTypes = ['sonata_type_collection'];
         // NEXT_MAJOR: Use only FQCNs when dropping support for Symfony <2.8
         if (method_exists('Symfony\Component\Form\AbstractType', 'getBlockPrefix')) {
-            $classTypes = array(
+            $classTypes = [
                 'Sonata\AdminBundle\Form\Type\ModelType',
                 'Sonata\AdminBundle\Form\Type\ModelListType',
-            );
+            ];
             foreach ($classTypes as $classType) {
                 array_push(
                     $modelTypes,
diff --git a/Tests/Builder/ListBuilderTest.php b/Tests/Builder/ListBuilderTest.php
index 52c530b0..556ece44 100644
--- a/Tests/Builder/ListBuilderTest.php
+++ b/Tests/Builder/ListBuilderTest.php
@@ -11,6 +11,7 @@
 
 namespace Sonata\DoctrineORMAdminBundle\Tests\Builder;
 
+use PHPUnit\Framework\TestCase;
 use Prophecy\Argument;
 use Sonata\AdminBundle\Admin\AdminInterface;
 use Sonata\AdminBundle\Guesser\TypeGuesserInterface;
@@ -23,7 +24,7 @@
 /**
  * @author Andrew Mor-Yaroslavtsev <andrejs@gmail.com>
  */
-class ListBuilderTest extends \PHPUnit_Framework_TestCase
+class ListBuilderTest extends TestCase
 {
     /**
      * @var TypeGuesserInterface|\Prophecy\Prophecy\ObjectProphecy
@@ -81,7 +82,7 @@ public function testCorrectFixedActionsFieldType()
         $this->typeGuesser->guessType(
             Argument::any(), Argument::any(), Argument::any()
         )->willReturn(
-            new TypeGuess(null, array(), Guess::LOW_CONFIDENCE)
+            new TypeGuess(null, [], Guess::LOW_CONFIDENCE)
         );
 
         $fieldDescription = new FieldDescription();
diff --git a/Tests/Filter/BooleanFilterTest.php b/Tests/Filter/BooleanFilterTest.php
index d7595519..19201131 100644
--- a/Tests/Filter/BooleanFilterTest.php
+++ b/Tests/Filter/BooleanFilterTest.php
@@ -20,7 +20,7 @@ class BooleanFilterTest extends FilterWithQueryBuilderTest
     public function testFilterEmpty()
     {
         $filter = new BooleanFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
@@ -29,8 +29,8 @@ public function testFilterEmpty()
         $filter->filter($builder, 'alias', 'field', 'test');
         $filter->filter($builder, 'alias', 'field', false);
 
-        $filter->filter($builder, 'alias', 'field', array());
-        $filter->filter($builder, 'alias', 'field', array(null, 'test'));
+        $filter->filter($builder, 'alias', 'field', []);
+        $filter->filter($builder, 'alias', 'field', [null, 'test']);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -38,11 +38,11 @@ public function testFilterEmpty()
     public function testFilterNo()
     {
         $filter = new BooleanFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => null, 'value' => BooleanType::TYPE_NO));
+        $filter->filter($builder, 'alias', 'field', ['type' => null, 'value' => BooleanType::TYPE_NO]);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -50,11 +50,11 @@ public function testFilterNo()
     public function testFilterYes()
     {
         $filter = new BooleanFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => null, 'value' => BooleanType::TYPE_YES));
+        $filter->filter($builder, 'alias', 'field', ['type' => null, 'value' => BooleanType::TYPE_YES]);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -62,11 +62,11 @@ public function testFilterYes()
     public function testFilterArray()
     {
         $filter = new BooleanFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => null, 'value' => array(BooleanType::TYPE_NO)));
+        $filter->filter($builder, 'alias', 'field', ['type' => null, 'value' => [BooleanType::TYPE_NO]]);
 
         $this->assertEquals(true, $filter->isActive());
     }
diff --git a/Tests/Filter/CallbackFilterTest.php b/Tests/Filter/CallbackFilterTest.php
index bd09cd2a..10b53a2e 100644
--- a/Tests/Filter/CallbackFilterTest.php
+++ b/Tests/Filter/CallbackFilterTest.php
@@ -21,15 +21,15 @@ public function testFilterClosureEmpty()
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter = new CallbackFilter();
-        $filter->initialize('field_name', array(
+        $filter->initialize('field_name', [
             'callback' => function ($builder, $alias, $field, $value) {
                 return true;
             },
-        ));
+        ]);
 
         $filter->filter($builder, 'alias', 'field', false);
         $filter->filter($builder, 'alias', 'field', 'scalarValue');
-        $filter->filter($builder, 'alias', 'field', array('value' => ''));
+        $filter->filter($builder, 'alias', 'field', ['value' => '']);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -39,13 +39,13 @@ public function testFilterClosureNotEmpty()
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter = new CallbackFilter();
-        $filter->initialize('field_name', array(
+        $filter->initialize('field_name', [
             'callback' => function ($builder, $alias, $field, $value) {
                 return true;
             },
-        ));
+        ]);
 
-        $filter->filter($builder, 'alias', 'field', array('value' => 'myValue'));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'myValue']);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -55,13 +55,13 @@ public function testFilterMethodEmpty()
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter = new CallbackFilter();
-        $filter->initialize('field_name', array(
-            'callback' => array($this, 'customCallback'),
-        ));
+        $filter->initialize('field_name', [
+            'callback' => [$this, 'customCallback'],
+        ]);
 
         $filter->filter($builder, 'alias', 'field', false);
         $filter->filter($builder, 'alias', 'field', 'scalarValue');
-        $filter->filter($builder, 'alias', 'field', array('value' => ''));
+        $filter->filter($builder, 'alias', 'field', ['value' => '']);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -71,11 +71,11 @@ public function testFilterMethodNotEmpty()
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter = new CallbackFilter();
-        $filter->initialize('field_name', array(
-            'callback' => array($this, 'customCallback'),
-        ));
+        $filter->initialize('field_name', [
+            'callback' => [$this, 'customCallback'],
+        ]);
 
-        $filter->filter($builder, 'alias', 'field', array('value' => 'myValue'));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'myValue']);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -93,7 +93,7 @@ public function testFilterException()
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter = new CallbackFilter();
-        $filter->initialize('field_name', array());
+        $filter->initialize('field_name', []);
 
         $filter->filter($builder, 'alias', 'field', 'myValue');
     }
diff --git a/Tests/Filter/ChoiceFilterTest.php b/Tests/Filter/ChoiceFilterTest.php
index ff42b7ac..a42e1da0 100644
--- a/Tests/Filter/ChoiceFilterTest.php
+++ b/Tests/Filter/ChoiceFilterTest.php
@@ -20,13 +20,13 @@ class ChoiceFilterTest extends FilterWithQueryBuilderTest
     public function testFilterEmpty()
     {
         $filter = new ChoiceFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter->filter($builder, 'alias', 'field', null);
         $filter->filter($builder, 'alias', 'field', 'all');
-        $filter->filter($builder, 'alias', 'field', array());
+        $filter->filter($builder, 'alias', 'field', []);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -34,11 +34,11 @@ public function testFilterEmpty()
     public function testFilterArray()
     {
         $filter = new ChoiceFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => ChoiceType::TYPE_CONTAINS, 'value' => array('1', '2')));
+        $filter->filter($builder, 'alias', 'field', ['type' => ChoiceType::TYPE_CONTAINS, 'value' => ['1', '2']]);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -46,11 +46,11 @@ public function testFilterArray()
     public function testFilterScalar()
     {
         $filter = new ChoiceFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => ChoiceType::TYPE_CONTAINS, 'value' => '1'));
+        $filter->filter($builder, 'alias', 'field', ['type' => ChoiceType::TYPE_CONTAINS, 'value' => '1']);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -58,11 +58,11 @@ public function testFilterScalar()
     public function testFilterZero()
     {
         $filter = new ChoiceFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => ChoiceType::TYPE_CONTAINS, 'value' => 0));
+        $filter->filter($builder, 'alias', 'field', ['type' => ChoiceType::TYPE_CONTAINS, 'value' => 0]);
 
         $this->assertEquals(true, $filter->isActive());
     }
diff --git a/Tests/Filter/FilterTest.php b/Tests/Filter/FilterTest.php
index 07e281fa..4acac383 100644
--- a/Tests/Filter/FilterTest.php
+++ b/Tests/Filter/FilterTest.php
@@ -11,6 +11,7 @@
 
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Filter;
 
+use PHPUnit\Framework\TestCase;
 use Sonata\AdminBundle\Datagrid\ProxyQueryInterface;
 use Sonata\DoctrineMongoDBAdminBundle\Filter\Filter;
 
@@ -31,15 +32,15 @@ public function filter(ProxyQueryInterface $queryBuilder, $alias, $field, $value
 
     public function getDefaultOptions()
     {
-        return array('option1' => 2);
+        return ['option1' => 2];
     }
 
     public function getRenderSettings()
     {
-        return array('sonata_type_filter_default', array(
+        return ['sonata_type_filter_default', [
             'type' => $this->getFieldType(),
             'options' => $this->getFieldOptions(),
-        ));
+        ]];
     }
 
     public function testAssociation(ProxyQueryInterface $queryBuilder, $value)
@@ -48,15 +49,15 @@ public function testAssociation(ProxyQueryInterface $queryBuilder, $value)
     }
 }
 
-class FilterTest extends \PHPUnit_Framework_TestCase
+class FilterTest extends TestCase
 {
     public function testFieldDescription()
     {
         $filter = new FilterTest_Filter();
-        $this->assertEquals(array('option1' => 2), $filter->getDefaultOptions());
+        $this->assertEquals(['option1' => 2], $filter->getDefaultOptions());
         $this->assertEquals(null, $filter->getOption('1'));
 
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $this->assertEquals(2, $filter->getOption('option1'));
         $this->assertEquals(null, $filter->getOption('foo'));
@@ -69,7 +70,7 @@ public function testFieldDescription()
             : 'text',
             $filter->getFieldType()
         );
-        $this->assertEquals(array('class' => 'FooBar'), $filter->getFieldOptions());
+        $this->assertEquals(['class' => 'FooBar'], $filter->getFieldOptions());
     }
 
     public function testValues()
diff --git a/Tests/Filter/FilterWithQueryBuilderTest.php b/Tests/Filter/FilterWithQueryBuilderTest.php
index ae018117..341d22c6 100644
--- a/Tests/Filter/FilterWithQueryBuilderTest.php
+++ b/Tests/Filter/FilterWithQueryBuilderTest.php
@@ -11,9 +11,9 @@
 
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Filter;
 
-use Sonata\DoctrineMongoDBAdminBundle\Tests\Helpers\PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase;
 
-abstract class FilterWithQueryBuilderTest extends PHPUnit_Framework_TestCase
+abstract class FilterWithQueryBuilderTest extends TestCase
 {
     private $queryBuilder = null;
     private $expr = null;
diff --git a/Tests/Filter/ModelFilterTest.php b/Tests/Filter/ModelFilterTest.php
index 48ba22b5..01a2db6a 100644
--- a/Tests/Filter/ModelFilterTest.php
+++ b/Tests/Filter/ModelFilterTest.php
@@ -43,12 +43,12 @@ public function getFieldDescription(array $options)
     public function testFilterEmpty()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
         $filter->filter($builder, 'alias', 'field', null);
-        $filter->filter($builder, 'alias', 'field', array());
+        $filter->filter($builder, 'alias', 'field', []);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -56,14 +56,14 @@ public function testFilterEmpty()
     public function testFilterArray()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar'), 'field_mapping' => true));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar'], 'field_mapping' => true]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array(
+        $filter->filter($builder, 'alias', 'field', [
             'type' => EqualType::TYPE_IS_EQUAL,
-            'value' => array(new DocumentStub(), new DocumentStub()),
-        ));
+            'value' => [new DocumentStub(), new DocumentStub()],
+        ]);
 
         // the alias is now computer by the entityJoin method
         $this->assertEquals(true, $filter->isActive());
@@ -72,11 +72,11 @@ public function testFilterArray()
     public function testFilterScalar()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar'), 'field_mapping' => true));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar'], 'field_mapping' => true]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()));
+        $filter->filter($builder, 'alias', 'field', ['type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()]);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -87,7 +87,7 @@ public function testFilterScalar()
     public function testAssociationWithInvalidMapping()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array('mapping_type' => 'foo', 'field_mapping' => true));
+        $filter->initialize('field_name', ['mapping_type' => 'foo', 'field_mapping' => true]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
@@ -100,7 +100,7 @@ public function testAssociationWithInvalidMapping()
     public function testAssociationWithValidMappingAndEmptyFieldName()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array('mapping_type' => ClassMetadataInfo::ONE, 'field_mapping' => true));
+        $filter->initialize('field_name', ['mapping_type' => ClassMetadataInfo::ONE, 'field_mapping' => true]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
@@ -111,17 +111,17 @@ public function testAssociationWithValidMappingAndEmptyFieldName()
     public function testAssociationWithValidMapping()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array(
+        $filter->initialize('field_name', [
             'mapping_type' => ClassMetadataInfo::ONE,
             'field_name' => 'field_name',
-            'association_mapping' => array(
+            'association_mapping' => [
                 'fieldName' => 'association_mapping',
-            ), 'field_mapping' => true,
-        ));
+            ], 'field_mapping' => true,
+        ]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->apply($builder, array('type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()));
+        $filter->apply($builder, ['type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()]);
 
         $this->assertEquals(true, $filter->isActive());
     }
@@ -129,25 +129,25 @@ public function testAssociationWithValidMapping()
     public function testAssociationWithValidParentAssociationMappings()
     {
         $filter = new ModelFilter();
-        $filter->initialize('field_name', array(
+        $filter->initialize('field_name', [
             'mapping_type' => ClassMetadataInfo::ONE,
             'field_name' => 'field_name',
-            'parent_association_mappings' => array(
-                array(
+            'parent_association_mappings' => [
+                [
                     'fieldName' => 'association_mapping',
-                ),
-                array(
+                ],
+                [
                     'fieldName' => 'sub_association_mapping',
-                ),
-            ),
-            'association_mapping' => array(
+                ],
+            ],
+            'association_mapping' => [
                 'fieldName' => 'sub_sub_association_mapping',
-            ), 'field_mapping' => true,
-        ));
+            ], 'field_mapping' => true,
+        ]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->apply($builder, array('type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()));
+        $filter->apply($builder, ['type' => EqualType::TYPE_IS_EQUAL, 'value' => new DocumentStub()]);
 
         $this->assertEquals(true, $filter->isActive());
     }
diff --git a/Tests/Filter/NumberFilterTest.php b/Tests/Filter/NumberFilterTest.php
index f23973eb..24c7b303 100644
--- a/Tests/Filter/NumberFilterTest.php
+++ b/Tests/Filter/NumberFilterTest.php
@@ -20,7 +20,7 @@ class NumberFilterTest extends FilterWithQueryBuilderTest
     public function testFilterEmpty()
     {
         $filter = new NumberFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
@@ -33,11 +33,11 @@ public function testFilterEmpty()
     public function testFilterInvalidOperator()
     {
         $filter = new NumberFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => 'foo'));
+        $filter->filter($builder, 'alias', 'field', ['type' => 'foo']);
 
         $this->assertEquals(false, $filter->isActive());
     }
@@ -45,16 +45,16 @@ public function testFilterInvalidOperator()
     public function testFilter()
     {
         $filter = new NumberFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('type' => NumberType::TYPE_EQUAL, 'value' => 42));
-        $filter->filter($builder, 'alias', 'field', array('type' => NumberType::TYPE_GREATER_EQUAL, 'value' => 42));
-        $filter->filter($builder, 'alias', 'field', array('type' => NumberType::TYPE_GREATER_THAN, 'value' => 42));
-        $filter->filter($builder, 'alias', 'field', array('type' => NumberType::TYPE_LESS_EQUAL, 'value' => 42));
-        $filter->filter($builder, 'alias', 'field', array('type' => NumberType::TYPE_LESS_THAN, 'value' => 42));
-        $filter->filter($builder, 'alias', 'field', array('value' => 42));
+        $filter->filter($builder, 'alias', 'field', ['type' => NumberType::TYPE_EQUAL, 'value' => 42]);
+        $filter->filter($builder, 'alias', 'field', ['type' => NumberType::TYPE_GREATER_EQUAL, 'value' => 42]);
+        $filter->filter($builder, 'alias', 'field', ['type' => NumberType::TYPE_GREATER_THAN, 'value' => 42]);
+        $filter->filter($builder, 'alias', 'field', ['type' => NumberType::TYPE_LESS_EQUAL, 'value' => 42]);
+        $filter->filter($builder, 'alias', 'field', ['type' => NumberType::TYPE_LESS_THAN, 'value' => 42]);
+        $filter->filter($builder, 'alias', 'field', ['value' => 42]);
 
         $this->assertEquals(true, $filter->isActive());
     }
diff --git a/Tests/Filter/StringFilterTest.php b/Tests/Filter/StringFilterTest.php
index 2df383ba..5cb8e945 100644
--- a/Tests/Filter/StringFilterTest.php
+++ b/Tests/Filter/StringFilterTest.php
@@ -21,7 +21,7 @@ class StringFilterTest extends FilterWithQueryBuilderTest
     public function testEmpty()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array('field_options' => array('class' => 'FooBar')));
+        $filter->initialize('field_name', ['field_options' => ['class' => 'FooBar']]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
@@ -34,80 +34,80 @@ public function testEmpty()
     public function testContains()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array('format' => '%s'));
+        $filter->initialize('field_name', ['format' => '%s']);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => null));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => null]);
         $this->assertEquals(true, $filter->isActive());
     }
 
     public function testNotContains()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array('format' => '%s'));
+        $filter->initialize('field_name', ['format' => '%s']);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => ChoiceType::TYPE_NOT_CONTAINS));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => ChoiceType::TYPE_NOT_CONTAINS]);
         $this->assertEquals(true, $filter->isActive());
     }
 
     public function testEquals()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array('format' => '%s'));
+        $filter->initialize('field_name', ['format' => '%s']);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => ChoiceType::TYPE_EQUAL));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => ChoiceType::TYPE_EQUAL]);
         $this->assertEquals(true, $filter->isActive());
     }
 
     public function testEqualsWithValidParentAssociationMappings()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array(
+        $filter->initialize('field_name', [
             'format' => '%s',
             'field_name' => 'field_name',
-            'parent_association_mappings' => array(
-                array(
+            'parent_association_mappings' => [
+                [
                     'fieldName' => 'association_mapping',
-                ),
-                array(
+                ],
+                [
                     'fieldName' => 'sub_association_mapping',
-                ),
-                array(
+                ],
+                [
                     'fieldName' => 'sub_sub_association_mapping',
-                ),
-            ),
-        ));
+                ],
+            ],
+        ]);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
 
-        $filter->apply($builder, array('type' => ChoiceType::TYPE_EQUAL, 'value' => 'asd'));
+        $filter->apply($builder, ['type' => ChoiceType::TYPE_EQUAL, 'value' => 'asd']);
         $this->assertEquals(true, $filter->isActive());
     }
 
     public function testOr()
     {
         $filter = new StringFilter();
-        $filter->initialize('field_name', array('format' => '%s'));
+        $filter->initialize('field_name', ['format' => '%s']);
         $filter->setCondition(Filter::CONDITION_OR);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
         $builder->getQueryBuilder()->expects($this->once())->method('addOr');
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS]);
         $this->assertEquals(true, $filter->isActive());
 
         $filter->setCondition(Filter::CONDITION_AND);
 
         $builder = new ProxyQuery($this->getQueryBuilder());
         $builder->getQueryBuilder()->expects($this->never())->method('addOr');
-        $filter->filter($builder, 'alias', 'field', array('value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS));
+        $filter->filter($builder, 'alias', 'field', ['value' => 'asd', 'type' => ChoiceType::TYPE_CONTAINS]);
         $this->assertEquals(true, $filter->isActive());
     }
 }
diff --git a/Tests/Guesser/FilterTypeGuesserTest.php b/Tests/Guesser/FilterTypeGuesserTest.php
index 1c33a786..9686e867 100644
--- a/Tests/Guesser/FilterTypeGuesserTest.php
+++ b/Tests/Guesser/FilterTypeGuesserTest.php
@@ -11,9 +11,10 @@
 
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Guesser;
 
+use PHPUnit\Framework\TestCase;
 use Sonata\DoctrineMongoDBAdminBundle\Guesser\FilterTypeGuesser;
 
-class FilterTypeGuesserTest extends \PHPUnit_Framework_TestCase
+class FilterTypeGuesserTest extends TestCase
 {
     private $guesser;
     private $modelManager;
@@ -33,11 +34,11 @@ public function testThrowsOnMissingField()
     {
         $class = 'My\Model';
         $property = 'whatever';
-        $this->modelManager->getParentMetadataForProperty($class, $property)->willReturn(array(
+        $this->modelManager->getParentMetadataForProperty($class, $property)->willReturn([
             $this->metadata->reveal(),
             $property,
             'parent mappings, no idea what it looks like',
-        ));
+        ]);
         $this->guesser->guessType($class, $property, $this->modelManager->reveal());
     }
 }
diff --git a/Tests/Helpers/PHPUnit_Framework_TestCase.php b/Tests/Helpers/PHPUnit_Framework_TestCase.php
deleted file mode 100644
index d4ea99d7..00000000
--- a/Tests/Helpers/PHPUnit_Framework_TestCase.php
+++ /dev/null
@@ -1,58 +0,0 @@
-<?php
-
-/*
- * This file is part of the Sonata Project package.
- *
- * (c) Thomas Rabaix <thomas.rabaix@sonata-project.org>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Helpers;
-
-/**
- * This is helpers class for supporting old and new PHPUnit versions.
- *
- * @todo NEXT_MAJOR: Remove this class when dropping support for < PHPUnit 5.4.
- *
- * @author Oskar Stark <oskarstark@googlemail.com>
- */
-class PHPUnit_Framework_TestCase extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * {@inheritdoc}
-     */
-    public function expectException($exception, $message = '', $code = null)
-    {
-        if (is_callable('parent::expectException')) {
-            parent::expectException($exception);
-
-            if ('' !== $message) {
-                parent::expectExceptionMessage($message);
-            }
-
-            if (null !== $code) {
-                parent::expectExceptionCode($code);
-            }
-        }
-
-        return parent::setExpectedException($exception, $message, $code);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    protected function createMock($originalClassName)
-    {
-        if (is_callable('parent::createMock')) {
-            return parent::createMock($originalClassName);
-        }
-
-        return parent::getMockBuilder($originalClassName)
-            ->disableOriginalConstructor()
-            ->disableOriginalClone()
-            ->disableArgumentCloning()
-            ->getMock();
-    }
-}
diff --git a/Tests/Model/ModelManagerTest.php b/Tests/Model/ModelManagerTest.php
index 61d7ca3c..486c668a 100644
--- a/Tests/Model/ModelManagerTest.php
+++ b/Tests/Model/ModelManagerTest.php
@@ -11,10 +11,10 @@
 
 namespace Sonata\DoctrineMongoDBAdminBundle\Tests\Model;
 
+use PHPUnit\Framework\TestCase;
 use Sonata\DoctrineMongoDBAdminBundle\Model\ModelManager;
-use Sonata\DoctrineMongoDBAdminBundle\Tests\Helpers\PHPUnit_Framework_TestCase;
 
-class ModelManagerTest extends PHPUnit_Framework_TestCase
+class ModelManagerTest extends TestCase
 {
     public function testFilterEmpty()
     {
diff --git a/Util/ObjectAclManipulator.php b/Util/ObjectAclManipulator.php
index 825919a4..6ca4155d 100644
--- a/Util/ObjectAclManipulator.php
+++ b/Util/ObjectAclManipulator.php
@@ -48,7 +48,7 @@ public function batchConfigureAcls(OutputInterface $output, AdminInterface $admi
         try {
             $batchSize = 20;
             $batchSizeOutput = 200;
-            $objectIds = array();
+            $objectIds = [];
 
             foreach ($qb->getQuery()->iterate() as $row) {
                 $objectIds[] = ObjectIdentity::fromDomainObject($row);
@@ -63,7 +63,7 @@ public function batchConfigureAcls(OutputInterface $output, AdminInterface $admi
                     list($batchAdded, $batchUpdated) = $this->configureAcls($output, $admin, $objectIdIterator, $securityIdentity);
                     $countAdded += $batchAdded;
                     $countUpdated += $batchUpdated;
-                    $objectIds = array();
+                    $objectIds = [];
                 }
 
                 if (0 == ($count % $batchSizeOutput)) {
diff --git a/composer.json b/composer.json
index c475b08a..d86489a6 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
         }
     ],
     "require": {
-        "php": "^5.3 || ^7.0",
+        "php": "^5.6 || ^7.0",
         "doctrine/mongodb-odm": "^1.0",
         "doctrine/mongodb-odm-bundle": "^3.0",
         "sonata-project/admin-bundle": "^3.1"