diff --git a/tests/Functional/ButLastTest.php b/tests/Functional/ButLastTest.php
index 97481f79..740a3e62 100644
--- a/tests/Functional/ButLastTest.php
+++ b/tests/Functional/ButLastTest.php
@@ -16,7 +16,7 @@
 
 class ButLastTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [1, 2, 3, 4];
diff --git a/tests/Functional/ConcatTest.php b/tests/Functional/ConcatTest.php
index 19cb3c7c..d1a64be3 100644
--- a/tests/Functional/ConcatTest.php
+++ b/tests/Functional/ConcatTest.php
@@ -14,7 +14,7 @@
 
 class ConcatTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
     }
diff --git a/tests/Functional/DifferenceTest.php b/tests/Functional/DifferenceTest.php
index e785c4e5..01d924d9 100644
--- a/tests/Functional/DifferenceTest.php
+++ b/tests/Functional/DifferenceTest.php
@@ -29,7 +29,7 @@ class DifferenceTest extends AbstractTestCase
     /** @var Traversable|float[] */
     private $floatIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->intArray = [1 => 1, 2, "foo" => 3, 4];
diff --git a/tests/Functional/DropTest.php b/tests/Functional/DropTest.php
index 6e2cf610..bff99985 100644
--- a/tests/Functional/DropTest.php
+++ b/tests/Functional/DropTest.php
@@ -18,7 +18,7 @@
 
 class DropTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value1', 'value2', 'value3', 'value4'];
diff --git a/tests/Functional/EachTest.php b/tests/Functional/EachTest.php
index a0e7afdd..9ed67ce2 100644
--- a/tests/Functional/EachTest.php
+++ b/tests/Functional/EachTest.php
@@ -22,7 +22,7 @@ class EachTest extends AbstractTestCase
      */
     private $cb;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->cb = $this->getMockBuilder('cb')
diff --git a/tests/Functional/EveryTest.php b/tests/Functional/EveryTest.php
index 0d6f8ff1..5bba8c28 100644
--- a/tests/Functional/EveryTest.php
+++ b/tests/Functional/EveryTest.php
@@ -30,7 +30,7 @@ class EveryTest extends AbstractTestCase
     /** @var Traversable|string[] */
     private $badIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->goodArray = ['value', 'value', 'value'];
diff --git a/tests/Functional/Exceptions/InvalidArgumentExceptionTest.php b/tests/Functional/Exceptions/InvalidArgumentExceptionTest.php
index 8fc64fa9..82b868a8 100644
--- a/tests/Functional/Exceptions/InvalidArgumentExceptionTest.php
+++ b/tests/Functional/Exceptions/InvalidArgumentExceptionTest.php
@@ -8,8 +8,9 @@
  * @link      https://github.com/lstrojny/functional-php
  */
 
-namespace Functional\Exceptions;
+namespace Functional\Tests\Exceptions;
 
+use Functional\Exceptions\InvalidArgumentException;
 use PHPUnit\Framework\TestCase;
 
 class InvalidArgumentExceptionTest extends TestCase
diff --git a/tests/Functional/FalseTest.php b/tests/Functional/FalseTest.php
index 55bfca3f..14de1007 100644
--- a/tests/Functional/FalseTest.php
+++ b/tests/Functional/FalseTest.php
@@ -40,7 +40,7 @@ class FalseTest extends AbstractTestCase
     /** @var Traversable */
     private $falseHashIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->trueArray = [false, false, false, false];
diff --git a/tests/Functional/FalsyTest.php b/tests/Functional/FalsyTest.php
index a213b80f..5e505bd9 100644
--- a/tests/Functional/FalsyTest.php
+++ b/tests/Functional/FalsyTest.php
@@ -41,7 +41,7 @@ class FalsyTest extends AbstractTestCase
     /** @var Traversable */
     private $falseHashIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->trueArray = [false, null, false, false, 0];
diff --git a/tests/Functional/FirstTest.php b/tests/Functional/FirstTest.php
index c900f922..c8f64f23 100644
--- a/tests/Functional/FirstTest.php
+++ b/tests/Functional/FirstTest.php
@@ -30,7 +30,7 @@ public function getAliases(): array
         ];
     }
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['first', 'second', 'third'];
diff --git a/tests/Functional/FlatMapTest.php b/tests/Functional/FlatMapTest.php
index c0385d5c..766198a9 100644
--- a/tests/Functional/FlatMapTest.php
+++ b/tests/Functional/FlatMapTest.php
@@ -17,7 +17,7 @@
 
 class FlatMapTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['a', ['b'], ['C' => 'c'], [['d']], null];
diff --git a/tests/Functional/FlattenTest.php b/tests/Functional/FlattenTest.php
index c92c63db..f0643da8 100644
--- a/tests/Functional/FlattenTest.php
+++ b/tests/Functional/FlattenTest.php
@@ -27,7 +27,7 @@ class FlattenTest extends AbstractTestCase
     /** @var Traversable */
     private $goodIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->goodArray = [1, 2, 3, [4, 5, 6, [7, 8, 9]], 10, [11, [12, 13], 14], 15];
diff --git a/tests/Functional/GroupTest.php b/tests/Functional/GroupTest.php
index fd9fe353..d8ea2f1c 100644
--- a/tests/Functional/GroupTest.php
+++ b/tests/Functional/GroupTest.php
@@ -17,7 +17,7 @@
 
 class GroupTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value1', 'value2', 'value3', 'value4'];
diff --git a/tests/Functional/InvokeFirstTest.php b/tests/Functional/InvokeFirstTest.php
index 2bb3be8b..4b86e102 100644
--- a/tests/Functional/InvokeFirstTest.php
+++ b/tests/Functional/InvokeFirstTest.php
@@ -29,7 +29,7 @@ class InvokeFirstTest extends AbstractTestCase
     /** @var Traversable */
     private $iteratorVeryFirstNotCallable;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [$this, null, null];
diff --git a/tests/Functional/InvokeLastTest.php b/tests/Functional/InvokeLastTest.php
index 8a508795..e3bbe863 100644
--- a/tests/Functional/InvokeLastTest.php
+++ b/tests/Functional/InvokeLastTest.php
@@ -24,7 +24,7 @@ class InvokeLastTest extends AbstractTestCase
 
     private $keyArray;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [null, null, $this];
diff --git a/tests/Functional/InvokeTest.php b/tests/Functional/InvokeTest.php
index 5b97f31b..e85ca6d8 100644
--- a/tests/Functional/InvokeTest.php
+++ b/tests/Functional/InvokeTest.php
@@ -23,7 +23,7 @@ class InvokeTest extends AbstractTestCase
     /** @var Traversable */
     private $keyIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [$this, $this, $this];
diff --git a/tests/Functional/LastTest.php b/tests/Functional/LastTest.php
index 99b05115..9417112d 100644
--- a/tests/Functional/LastTest.php
+++ b/tests/Functional/LastTest.php
@@ -24,7 +24,7 @@ class LastTest extends AbstractTestCase
     /** @var Traversable|string[] */
     private $badIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['first', 'second', 'third', 'fourth'];
diff --git a/tests/Functional/MapTest.php b/tests/Functional/MapTest.php
index 039c41c1..615f4bab 100644
--- a/tests/Functional/MapTest.php
+++ b/tests/Functional/MapTest.php
@@ -17,7 +17,7 @@
 
 class MapTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value', 'value'];
diff --git a/tests/Functional/MaximumTest.php b/tests/Functional/MaximumTest.php
index a170afb5..91a155e5 100644
--- a/tests/Functional/MaximumTest.php
+++ b/tests/Functional/MaximumTest.php
@@ -17,7 +17,7 @@
 
 class MaximumTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [1, "foo", 5.1, 5, "5.2", true, false, [], new stdClass()];
diff --git a/tests/Functional/MemoizeTest.php b/tests/Functional/MemoizeTest.php
index 926294a7..5f83c707 100644
--- a/tests/Functional/MemoizeTest.php
+++ b/tests/Functional/MemoizeTest.php
@@ -42,7 +42,7 @@ public static function call(): string
         return 'STATIC METHOD VALUE' . self::invoke(__METHOD__);
     }
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->callback = $this->getMockBuilder('stdClass')
diff --git a/tests/Functional/MinimumTest.php b/tests/Functional/MinimumTest.php
index f2c241ac..2cb92b65 100644
--- a/tests/Functional/MinimumTest.php
+++ b/tests/Functional/MinimumTest.php
@@ -17,7 +17,7 @@
 
 class MinimumTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [1, "foo", 5.1, 5, "5.2", true, false, [], new stdClass()];
diff --git a/tests/Functional/NoneTest.php b/tests/Functional/NoneTest.php
index 52ed1058..a1d1a3ba 100644
--- a/tests/Functional/NoneTest.php
+++ b/tests/Functional/NoneTest.php
@@ -29,7 +29,7 @@ class NoneTest extends AbstractTestCase
     /** @var Traversable|string[] */
     private $badIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->goodArray = ['value', 'value', 'value'];
diff --git a/tests/Functional/PartitionTest.php b/tests/Functional/PartitionTest.php
index 28ff216b..ad931752 100644
--- a/tests/Functional/PartitionTest.php
+++ b/tests/Functional/PartitionTest.php
@@ -17,7 +17,7 @@
 
 class PartitionTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value1', 'value2', 'value3'];
diff --git a/tests/Functional/PickTest.php b/tests/Functional/PickTest.php
index 3695bc48..feadfae8 100644
--- a/tests/Functional/PickTest.php
+++ b/tests/Functional/PickTest.php
@@ -19,7 +19,7 @@ class PickTest extends AbstractTestCase
 {
     private $array_1;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->array_1 = [
diff --git a/tests/Functional/PluckTest.php b/tests/Functional/PluckTest.php
index dcbcdc9a..4159ce56 100644
--- a/tests/Functional/PluckTest.php
+++ b/tests/Functional/PluckTest.php
@@ -123,7 +123,7 @@ class PluckTest extends AbstractTestCase
     /** @var Traversable */
     private $getExceptionIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->propertyExistsEverywhereArray = [(object)['property' => 1], (object)['property' => 2]];
diff --git a/tests/Functional/PollTest.php b/tests/Functional/PollTest.php
index 9f635c8b..67aead2a 100644
--- a/tests/Functional/PollTest.php
+++ b/tests/Functional/PollTest.php
@@ -25,7 +25,7 @@ class PollTest extends AbstractTestCase
     /** @var MockObject */
     private $poller;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->poller = $this->createMock(Poller::class);
diff --git a/tests/Functional/ProductTest.php b/tests/Functional/ProductTest.php
index bbe7f6ab..bc214228 100644
--- a/tests/Functional/ProductTest.php
+++ b/tests/Functional/ProductTest.php
@@ -29,7 +29,7 @@ class ProductTest extends AbstractTestCase
     /** @var Traversable|float[] */
     private $floatIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->intArray = [1 => 1, 2, "foo" => 3, 4];
diff --git a/tests/Functional/RatioTest.php b/tests/Functional/RatioTest.php
index cc381ce7..802e774a 100644
--- a/tests/Functional/RatioTest.php
+++ b/tests/Functional/RatioTest.php
@@ -29,7 +29,7 @@ class RatioTest extends AbstractTestCase
     /** @var Traversable|float[] */
     private $floatIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->intArray = [1 => 1, 2, "foo" => 3, 4];
diff --git a/tests/Functional/ReduceTest.php b/tests/Functional/ReduceTest.php
index 8fdcfe61..ab53dd3b 100644
--- a/tests/Functional/ReduceTest.php
+++ b/tests/Functional/ReduceTest.php
@@ -20,7 +20,7 @@ class ReduceTest extends AbstractTestCase
     /** @var iterable */
     private $currentCollection;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['one', 'two', 'three'];
diff --git a/tests/Functional/ReindexTest.php b/tests/Functional/ReindexTest.php
index d094b6de..3880db94 100644
--- a/tests/Functional/ReindexTest.php
+++ b/tests/Functional/ReindexTest.php
@@ -17,7 +17,7 @@
 
 class ReindexTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value', 'value'];
diff --git a/tests/Functional/RejectTest.php b/tests/Functional/RejectTest.php
index 49c87bc7..141e0048 100644
--- a/tests/Functional/RejectTest.php
+++ b/tests/Functional/RejectTest.php
@@ -17,7 +17,7 @@
 
 class RejectTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value', 'wrong', 'value'];
diff --git a/tests/Functional/RepeatTest.php b/tests/Functional/RepeatTest.php
index 9ab5e8a4..8f6ebab6 100644
--- a/tests/Functional/RepeatTest.php
+++ b/tests/Functional/RepeatTest.php
@@ -27,7 +27,7 @@ class RepeatTest extends AbstractTestCase
     /** @var Repeated|MockObject */
     private $repeated;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->repeated = $this->createMock(Repeated::class);
diff --git a/tests/Functional/RetryTest.php b/tests/Functional/RetryTest.php
index 5c8dd5fc..7376c715 100644
--- a/tests/Functional/RetryTest.php
+++ b/tests/Functional/RetryTest.php
@@ -26,7 +26,7 @@ class RetryTest extends AbstractTestCase
     /** @var MockObject */
     private $retryer;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->retryer = $this->createMock(Retryer::class);
diff --git a/tests/Functional/SelectTest.php b/tests/Functional/SelectTest.php
index 8eaded12..901f8dcd 100644
--- a/tests/Functional/SelectTest.php
+++ b/tests/Functional/SelectTest.php
@@ -25,7 +25,7 @@ public function getAliases(): array
         ];
     }
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value', 'wrong', 'value'];
diff --git a/tests/Functional/SomeTest.php b/tests/Functional/SomeTest.php
index 0e95da23..e7afb188 100644
--- a/tests/Functional/SomeTest.php
+++ b/tests/Functional/SomeTest.php
@@ -30,7 +30,7 @@ class SomeTest extends AbstractTestCase
     /** @var Traversable|string[] */
     private $badIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->goodArray = ['value', 'wrong'];
diff --git a/tests/Functional/SortTest.php b/tests/Functional/SortTest.php
index 1dd8892f..5525702f 100644
--- a/tests/Functional/SortTest.php
+++ b/tests/Functional/SortTest.php
@@ -19,7 +19,7 @@ class SortTest extends AbstractTestCase
     /** @var callable */
     private $sortCallback;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['cat', 'bear', 'aardvark'];
diff --git a/tests/Functional/SumTest.php b/tests/Functional/SumTest.php
index 144ccd42..8a1dbd26 100644
--- a/tests/Functional/SumTest.php
+++ b/tests/Functional/SumTest.php
@@ -29,7 +29,7 @@ class SumTest extends AbstractTestCase
     /** @var Traversable */
     private $floatIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->intArray = [1 => 1, 2, "foo" => 3];
diff --git a/tests/Functional/TailTest.php b/tests/Functional/TailTest.php
index 3b24a8ad..94e4ee67 100644
--- a/tests/Functional/TailTest.php
+++ b/tests/Functional/TailTest.php
@@ -24,7 +24,7 @@ class TailTest extends AbstractTestCase
     /** @var Traversable */
     private $badIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = [1, 2, 3, 4];
diff --git a/tests/Functional/TakeLeftTest.php b/tests/Functional/TakeLeftTest.php
index fbeed7a4..7b393a67 100644
--- a/tests/Functional/TakeLeftTest.php
+++ b/tests/Functional/TakeLeftTest.php
@@ -17,7 +17,7 @@
 
 class TakeLeftTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Functional/TakeRightTest.php b/tests/Functional/TakeRightTest.php
index 23d1dc86..3bd16162 100644
--- a/tests/Functional/TakeRightTest.php
+++ b/tests/Functional/TakeRightTest.php
@@ -17,7 +17,7 @@
 
 class TakeRightTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Functional/TapTest.php b/tests/Functional/TapTest.php
index 24eed944..00f6056e 100644
--- a/tests/Functional/TapTest.php
+++ b/tests/Functional/TapTest.php
@@ -14,7 +14,7 @@
 
 class TapTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
     }
diff --git a/tests/Functional/TrueTest.php b/tests/Functional/TrueTest.php
index 4ef097b3..d5efd678 100644
--- a/tests/Functional/TrueTest.php
+++ b/tests/Functional/TrueTest.php
@@ -40,7 +40,7 @@ class TrueTest extends AbstractTestCase
     /** @var bool[] */
     private $trueArray;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->trueArray = [true, true, true, true];
diff --git a/tests/Functional/TruthyTest.php b/tests/Functional/TruthyTest.php
index 1e64f454..80eaa9e7 100644
--- a/tests/Functional/TruthyTest.php
+++ b/tests/Functional/TruthyTest.php
@@ -41,7 +41,7 @@ class TruthyTest extends AbstractTestCase
     /** @var Traversable */
     private $falseHashIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->trueArray = [true, true, 'foo', true, true, 1];
diff --git a/tests/Functional/UniqueTest.php b/tests/Functional/UniqueTest.php
index 1001fe25..da4ddf75 100644
--- a/tests/Functional/UniqueTest.php
+++ b/tests/Functional/UniqueTest.php
@@ -23,7 +23,7 @@ class UniqueTest extends AbstractTestCase
     /** @var Traversable */
     private $mixedTypesIterator;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value1', 'value2', 'value1', 'value'];
diff --git a/tests/Functional/ZipTest.php b/tests/Functional/ZipTest.php
index aa1d7773..79d426c3 100644
--- a/tests/Functional/ZipTest.php
+++ b/tests/Functional/ZipTest.php
@@ -18,7 +18,7 @@
 
 class ZipTest extends AbstractTestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         parent::setUp();
         $this->list = ['value', 'value'];