diff --git a/.gitignore b/.gitignore
index c935546b..341b0891 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 composer.phar
 phpunit.xml
+.phpunit.result.cache
 vendor/
 data/schema.graphql
 composer.lock
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 00000000..0b428194
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,11 @@
+FROM php:8.3
+COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer
+RUN apt update
+RUN apt install git -y
+RUN apt-get install -y \
+        libzip-dev \
+        zip \
+  && docker-php-ext-install zip
+RUN pecl install xdebug && docker-php-ext-enable xdebug
+WORKDIR /var/www/html
+ENTRYPOINT ["tail", "-f", "/dev/null"]
diff --git a/composer.json b/composer.json
index a911fd8d..b0bf1ab1 100644
--- a/composer.json
+++ b/composer.json
@@ -13,12 +13,14 @@
     }
   ],
   "require": {
-    "php": ">=5.5",
+    "php": "^8.3",
     "ext-mbstring": "*",
-    "symfony/property-access": "^2.8 || ^3.4 || ^4.4 || ^5.4"
+    "symfony/property-access": "^2.8 || ^3.4 || ^4.4 || ^5.4 || ^6.4"
   },
   "require-dev": {
-    "phpunit/phpunit": "^4.8"
+    "phpunit/phpunit": "~9.6",
+    "rector/rector": "*",
+    "phpspec/prophecy": "^1.19"
   },
   "autoload": {
     "psr-4": {
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 00000000..bf353c98
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,7 @@
+services:
+  app:
+    hostname: app
+    container_name: app
+    build: .
+    volumes:
+      - .:/var/www/html:rw
diff --git a/rector.php b/rector.php
new file mode 100644
index 00000000..d58f2d58
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,20 @@
+<?php
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\PHPUnit\Set\PHPUnitSetList;
+
+return RectorConfig::configure()
+    ->withPaths([
+        // __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ])
+    ->withPhpSets(php83: true)
+    ->withSets([
+        PHPUnitSetList::PHPUNIT_50,
+        PHPUnitSetList::PHPUNIT_60,
+        PHPUnitSetList::PHPUNIT_70,
+        PHPUnitSetList::PHPUNIT_80,
+        PHPUnitSetList::PHPUNIT_90,
+        ])
+    ->withTypeCoverageLevel(0);
diff --git a/tests/DataProvider/TestConfig.php b/tests/DataProvider/TestConfig.php
index 802baae6..1369f756 100644
--- a/tests/DataProvider/TestConfig.php
+++ b/tests/DataProvider/TestConfig.php
@@ -14,6 +14,7 @@
 
 class TestConfig extends AbstractConfig
 {
+    #[\Override]
     public function getRules()
     {
         return [
diff --git a/tests/DataProvider/TestConfigExtraFields.php b/tests/DataProvider/TestConfigExtraFields.php
index f8aa17e6..f686f2b7 100644
--- a/tests/DataProvider/TestConfigExtraFields.php
+++ b/tests/DataProvider/TestConfigExtraFields.php
@@ -17,6 +17,7 @@ class TestConfigExtraFields extends AbstractConfig
 
     protected $extraFieldsAllowed = true;
 
+    #[\Override]
     public function getRules()
     {
         return [
diff --git a/tests/DataProvider/TestConfigInvalidRule.php b/tests/DataProvider/TestConfigInvalidRule.php
index 0a61ab85..e3362901 100644
--- a/tests/DataProvider/TestConfigInvalidRule.php
+++ b/tests/DataProvider/TestConfigInvalidRule.php
@@ -8,6 +8,7 @@
 
 class TestConfigInvalidRule extends AbstractConfig
 {
+    #[\Override]
     public function getRules()
     {
         return [
diff --git a/tests/DataProvider/TestEmptySchema.php b/tests/DataProvider/TestEmptySchema.php
index 004bc45e..22320b81 100644
--- a/tests/DataProvider/TestEmptySchema.php
+++ b/tests/DataProvider/TestEmptySchema.php
@@ -14,11 +14,13 @@
 
 class TestEmptySchema extends AbstractSchema
 {
+    #[\Override]
     public function build(SchemaConfig $config)
     {
     }
 
 
+    #[\Override]
     public function getName($config)
     {
         return 'TestSchema';
diff --git a/tests/DataProvider/TestEnumType.php b/tests/DataProvider/TestEnumType.php
index 90a1b8d8..ac0984ee 100644
--- a/tests/DataProvider/TestEnumType.php
+++ b/tests/DataProvider/TestEnumType.php
@@ -13,6 +13,7 @@
 
 class TestEnumType extends AbstractEnumType
 {
+    #[\Override]
     public function getValues()
     {
         return [
diff --git a/tests/DataProvider/TestExtendedType.php b/tests/DataProvider/TestExtendedType.php
index 4acc4252..eb91590a 100644
--- a/tests/DataProvider/TestExtendedType.php
+++ b/tests/DataProvider/TestExtendedType.php
@@ -15,6 +15,7 @@
 
 class TestExtendedType extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->applyInterface(new TestInterfaceType())
diff --git a/tests/DataProvider/TestField.php b/tests/DataProvider/TestField.php
index b1764754..9fef6524 100644
--- a/tests/DataProvider/TestField.php
+++ b/tests/DataProvider/TestField.php
@@ -18,16 +18,19 @@ class TestField extends AbstractField
     /**
      * @return AbstractObjectType
      */
+    #[\Override]
     public function getType()
     {
         return new IntType();
     }
 
+    #[\Override]
     public function resolve($value, array $args, ResolveInfo $info)
     {
         return $value;
     }
 
+    #[\Override]
     public function getDescription()
     {
         return 'description';
diff --git a/tests/DataProvider/TestInputField.php b/tests/DataProvider/TestInputField.php
index 2340e560..bf4a79ce 100644
--- a/tests/DataProvider/TestInputField.php
+++ b/tests/DataProvider/TestInputField.php
@@ -18,16 +18,19 @@ class TestInputField extends AbstractInputField
     /**
      * @return InputTypeInterface
      */
+    #[\Override]
     public function getType()
     {
         return new IntType();
     }
 
+    #[\Override]
     public function getDescription()
     {
         return 'description';
     }
 
+    #[\Override]
     public function getDefaultValue()
     {
         return 'default';
diff --git a/tests/DataProvider/TestInputObjectType.php b/tests/DataProvider/TestInputObjectType.php
index 95d34b0a..fe5f3499 100644
--- a/tests/DataProvider/TestInputObjectType.php
+++ b/tests/DataProvider/TestInputObjectType.php
@@ -15,6 +15,7 @@
 
 class TestInputObjectType extends AbstractInputObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addField('name', new NonNullType(new StringType()));
diff --git a/tests/DataProvider/TestInterfaceType.php b/tests/DataProvider/TestInterfaceType.php
index 68a562ad..70485829 100644
--- a/tests/DataProvider/TestInterfaceType.php
+++ b/tests/DataProvider/TestInterfaceType.php
@@ -15,11 +15,13 @@
 class TestInterfaceType extends AbstractInterfaceType
 {
 
+    #[\Override]
     public function resolveType($object)
     {
         return is_object($object) ? $object : new TestObjectType();
     }
 
+    #[\Override]
     public function build($config)
     {
         $config->addField('name', new StringType());
diff --git a/tests/DataProvider/TestListType.php b/tests/DataProvider/TestListType.php
index 87f779c4..644ed361 100644
--- a/tests/DataProvider/TestListType.php
+++ b/tests/DataProvider/TestListType.php
@@ -14,6 +14,7 @@
 
 class TestListType extends AbstractListType
 {
+    #[\Override]
     public function getItemType()
     {
         return new StringType();
diff --git a/tests/DataProvider/TestMutationObjectType.php b/tests/DataProvider/TestMutationObjectType.php
index c0747499..f4f19497 100644
--- a/tests/DataProvider/TestMutationObjectType.php
+++ b/tests/DataProvider/TestMutationObjectType.php
@@ -15,11 +15,13 @@
 
 class TestMutationObjectType extends AbstractMutationObjectType
 {
+    #[\Override]
     public function getOutputType()
     {
         return new StringType();
     }
 
+    #[\Override]
     public function build($config)
     {
         $this->addArgument('increment', new IntType());
diff --git a/tests/DataProvider/TestObjectType.php b/tests/DataProvider/TestObjectType.php
index f0e43a8b..41ffe4da 100644
--- a/tests/DataProvider/TestObjectType.php
+++ b/tests/DataProvider/TestObjectType.php
@@ -17,6 +17,7 @@
 class TestObjectType extends AbstractObjectType
 {
 
+    #[\Override]
     public function build($config)
     {
         $config
@@ -41,9 +42,7 @@ public function build($config)
                  'args'    => [
                      'noop' => new IntType()
                  ],
-                 'resolve' => function ($value, $args, $info) {
-                   return ['address' => '1234 Street'];
-                 }
+                 'resolve' => fn($value, $args, $info) => ['address' => '1234 Street']
              ]
             )
             ->addField(
@@ -52,13 +51,12 @@ public function build($config)
                     'args'    => [
                         'value' => new NonNullType(new StringType())
                     ],
-                    'resolve' => function ($value, $args, $info) {
-                        return $args['value'];
-                    }
+                    'resolve' => fn($value, $args, $info) => $args['value']
                 ]
             );
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new TestInterfaceType()];
diff --git a/tests/DataProvider/TestSchema.php b/tests/DataProvider/TestSchema.php
index 26726d83..f359dbac 100644
--- a/tests/DataProvider/TestSchema.php
+++ b/tests/DataProvider/TestSchema.php
@@ -19,28 +19,23 @@ class TestSchema extends AbstractSchema
 {
     private $testStatusValue = 0;
 
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->getQuery()->addFields([
             'me'     => [
                 'type'    => new TestObjectType(),
-                'resolve' => function ($value, $args, ResolveInfo $info) {
-                    return $info->getReturnType()->getData();
-                }
+                'resolve' => fn($value, $args, ResolveInfo $info) => $info->getReturnType()->getData()
             ],
             'status' => [
                 'type'    => new TestEnumType(),
-                'resolve' => function () {
-                    return $this->testStatusValue;
-                }
+                'resolve' => fn() => $this->testStatusValue
             ],
         ]);
         $config->getMutation()->addFields([
             'updateStatus' => [
                 'type'    => new TestEnumType(),
-                'resolve' => function () {
-                    return $this->testStatusValue;
-                },
+                'resolve' => fn() => $this->testStatusValue,
                 'args'    => [
                     'newStatus' => new TestEnumType(),
                     'list' => new ListType(new IntType())
diff --git a/tests/DataProvider/TestTimeType.php b/tests/DataProvider/TestTimeType.php
index 3d9f285b..42ddff6d 100644
--- a/tests/DataProvider/TestTimeType.php
+++ b/tests/DataProvider/TestTimeType.php
@@ -14,6 +14,7 @@
 class TestTimeType extends AbstractScalarType
 {
 
+    #[\Override]
     public function getName()
     {
         return 'TestTime';
@@ -23,6 +24,7 @@ public function getName()
      * @param $value \DateTime
      * @return null|string
      */
+    #[\Override]
     public function serialize($value)
     {
         if ($value === null) {
@@ -32,6 +34,7 @@ public function serialize($value)
         return $value instanceof \DateTime ? $value->format('H:i:s') : $value;
     }
 
+    #[\Override]
     public function isValidValue($value)
     {
         if (is_object($value)) {
@@ -43,6 +46,7 @@ public function isValidValue($value)
         return $d && $d->format('H:i:s') == $value;
     }
 
+    #[\Override]
     public function getDescription()
     {
         return 'Representation time in "H:i:s" format';
diff --git a/tests/DataProvider/TestUnionType.php b/tests/DataProvider/TestUnionType.php
index 96e1dd9c..16e01ffe 100644
--- a/tests/DataProvider/TestUnionType.php
+++ b/tests/DataProvider/TestUnionType.php
@@ -13,6 +13,7 @@
 class TestUnionType extends AbstractUnionType
 {
 
+    #[\Override]
     public function getTypes()
     {
         return [
@@ -20,11 +21,13 @@ public function getTypes()
         ];
     }
 
+    #[\Override]
     public function resolveType($object)
     {
         return $object;
     }
 
+    #[\Override]
     public function getDescription()
     {
         return 'Union collect cars types';
diff --git a/tests/Issues/Issue109/Issue109Schema.php b/tests/Issues/Issue109/Issue109Schema.php
index 8ba4ab8f..86268b0c 100644
--- a/tests/Issues/Issue109/Issue109Schema.php
+++ b/tests/Issues/Issue109/Issue109Schema.php
@@ -11,6 +11,7 @@
 class Issue109Schema extends AbstractSchema
 {
 
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->setQuery(
diff --git a/tests/Issues/Issue109/Issue109Test.php b/tests/Issues/Issue109/Issue109Test.php
index 0e6a9628..aaec2eca 100644
--- a/tests/Issues/Issue109/Issue109Test.php
+++ b/tests/Issues/Issue109/Issue109Test.php
@@ -4,7 +4,7 @@
 
 use Youshido\GraphQL\Execution\Processor;
 
-class Issue109Test extends \PHPUnit_Framework_TestCase
+class Issue109Test extends \PHPUnit\Framework\TestCase
 {
 
     public function testInternalVariableArgument()
diff --git a/tests/Issues/Issue116/Issue116Test.php b/tests/Issues/Issue116/Issue116Test.php
index 3ad2ce71..ddeab3d6 100644
--- a/tests/Issues/Issue116/Issue116Test.php
+++ b/tests/Issues/Issue116/Issue116Test.php
@@ -10,7 +10,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class Issue116Test extends \PHPUnit_Framework_TestCase
+class Issue116Test extends \PHPUnit\Framework\TestCase
 {
 
     public function testInternalVariableArgument()
@@ -48,14 +48,12 @@ public function testInternalVariableArgument()
                         'args'    => [
                             'first' => new IntType(),
                         ],
-                        'resolve' => function () {
-                            return [
-                                'pageInfo' => [
-                                    'totalEdges' => 10,
-                                    'cursors'    => []
-                                ]
-                            ];
-                        }
+                        'resolve' => fn() => [
+                            'pageInfo' => [
+                                'totalEdges' => 10,
+                                'cursors'    => []
+                            ]
+                        ]
                     ]
                 ]
             ])
diff --git a/tests/Issues/Issue131/Issue131Test.php b/tests/Issues/Issue131/Issue131Test.php
index 1372dca1..8679a410 100644
--- a/tests/Issues/Issue131/Issue131Test.php
+++ b/tests/Issues/Issue131/Issue131Test.php
@@ -12,7 +12,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class Issue131Test extends \PHPUnit_Framework_TestCase
+class Issue131Test extends \PHPUnit\Framework\TestCase
 {
 
     public function testInternalVariableArgument()
@@ -47,12 +47,10 @@ public function testInternalVariableArgument()
                                 ]
                             ]))
                         ],
-                        'resolve' => function ($source, $args) {
-                            return [
-                                'id' => '1',
-                                'name' => sprintf('Meeting with %d beans', count($args['related_beans'])),
-                            ];
-                        }
+                        'resolve' => fn($source, $args) => [
+                            'id' => '1',
+                            'name' => sprintf('Meeting with %d beans', count($args['related_beans'])),
+                        ]
                     ]
                 ]
             ])
diff --git a/tests/Issues/Issue149/Issue149Test.php b/tests/Issues/Issue149/Issue149Test.php
index f42df1dc..a8743a7f 100644
--- a/tests/Issues/Issue149/Issue149Test.php
+++ b/tests/Issues/Issue149/Issue149Test.php
@@ -11,7 +11,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class Issue149Test extends \PHPUnit_Framework_TestCase
+class Issue149Test extends \PHPUnit\Framework\TestCase
 {
     public function testInternalVariableArgument()
     {
@@ -36,25 +36,23 @@ public function testInternalVariableArgument()
                                 ])),
                             ],
                         ]),
-                        'resolve' => function () {
-                            return [
-                                'id'      => 1,
-                                'name'    => 'John',
-                                'age'     => 30,
-                                'friends' => [
-                                    [
-                                        'id'   => 2,
-                                        'name' => 'Friend 1',
-                                        'age'  => 31,
-                                    ],
-                                    [
-                                        'id'   => 3,
-                                        'name' => 'Friend 2',
-                                        'age'  => 32,
-                                    ],
+                        'resolve' => fn() => [
+                            'id'      => 1,
+                            'name'    => 'John',
+                            'age'     => 30,
+                            'friends' => [
+                                [
+                                    'id'   => 2,
+                                    'name' => 'Friend 1',
+                                    'age'  => 31,
                                 ],
-                            ];
-                        },
+                                [
+                                    'id'   => 3,
+                                    'name' => 'Friend 2',
+                                    'age'  => 32,
+                                ],
+                            ],
+                        ],
                     ],
                 ],
             ]),
diff --git a/tests/Issues/Issue151/Issue151Test.php b/tests/Issues/Issue151/Issue151Test.php
index b3f58900..5a162e48 100644
--- a/tests/Issues/Issue151/Issue151Test.php
+++ b/tests/Issues/Issue151/Issue151Test.php
@@ -10,10 +10,11 @@
 use Youshido\GraphQL\Type\Scalar\StringType;
 use Youshido\GraphQL\Type\Union\UnionType;
 
-class Issue151Test extends \PHPUnit_Framework_TestCase
+class Issue151Test extends \PHPUnit\Framework\TestCase
 {
     public function testInternalVariableArgument()
     {
+        $this->expectNotToPerformAssertions();
         $type1 = new ObjectType([
             'name'   => 'Type1',
             'fields' => [
@@ -47,18 +48,16 @@ public function testInternalVariableArgument()
                 'fields' => [
                     'list' => [
                         'type'    => new ListType($unionType),
-                        'resolve' => function () {
-                            return [
-                                [
-                                    'id'   => 1,
-                                    'name' => 'name',
-                                ],
-                                [
-                                    'id'    => 2,
-                                    'title' => 'title',
-                                ],
-                            ];
-                        },
+                        'resolve' => fn() => [
+                            [
+                                'id'   => 1,
+                                'name' => 'name',
+                            ],
+                            [
+                                'id'    => 2,
+                                'title' => 'title',
+                            ],
+                        ],
                     ],
                 ],
             ]),
diff --git a/tests/Issues/Issue171/Issue171Schema.php b/tests/Issues/Issue171/Issue171Schema.php
index 95110c24..203edb2a 100644
--- a/tests/Issues/Issue171/Issue171Schema.php
+++ b/tests/Issues/Issue171/Issue171Schema.php
@@ -8,6 +8,7 @@
 
 class Issue171Schema extends AbstractSchema
 {
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->getQuery()->addField(
@@ -21,6 +22,7 @@ public function build(SchemaConfig $config)
 
 class PlanType extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addField('kpi_status', [
@@ -31,6 +33,7 @@ public function build($config)
 
 class KpiStatusType extends AbstractEnumType
 {
+    #[\Override]
     public function getValues()
     {
         return [
diff --git a/tests/Issues/Issue171/Issue171Test.php b/tests/Issues/Issue171/Issue171Test.php
index f4163bc6..bb29936e 100644
--- a/tests/Issues/Issue171/Issue171Test.php
+++ b/tests/Issues/Issue171/Issue171Test.php
@@ -3,7 +3,7 @@
 
 use Youshido\GraphQL\Execution\Processor;
 
-class Issue171Test extends \PHPUnit_Framework_TestCase
+class Issue171Test extends \PHPUnit\Framework\TestCase
 {
     public function testItSetsDeprecationReasonToNullByDefault()
     {
@@ -13,9 +13,7 @@ public function testItSetsDeprecationReasonToNullByDefault()
         $processor->processPayload($this->getIntrospectionQuery(), []);
         $resp = $processor->getResponseData();
 
-        $enumTypes = array_filter($resp['data']['__schema']['types'], function($type){
-            return ($type['kind'] === 'ENUM');
-        });
+        $enumTypes = array_filter($resp['data']['__schema']['types'], fn($type) => $type['kind'] === 'ENUM');
 
         foreach ($enumTypes as $enumType) {
             foreach ($enumType['enumValues'] as $value) {
diff --git a/tests/Issues/Issue193/Issue193Test.php b/tests/Issues/Issue193/Issue193Test.php
index 80d673f0..329a9524 100644
--- a/tests/Issues/Issue193/Issue193Test.php
+++ b/tests/Issues/Issue193/Issue193Test.php
@@ -11,7 +11,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class Issue193Test extends \PHPUnit_Framework_TestCase
+class Issue193Test extends \PHPUnit\Framework\TestCase
 {
     public function testResolvedInterfacesShouldBeRegistered()
     {
@@ -21,9 +21,7 @@ public function testResolvedInterfacesShouldBeRegistered()
         $processor->processPayload($this->getIntrospectionQuery(), []);
         $resp = $processor->getResponseData();
 
-        $typeNames = array_map(function ($type) {
-            return $type['name'];
-        }, $resp['data']['__schema']['types']);
+        $typeNames = array_map(fn($type) => $type['name'], $resp['data']['__schema']['types']);
 
         // Check that all types are discovered
         $this->assertContains('ContentBlockInterface', $typeNames);
@@ -67,6 +65,7 @@ private function getIntrospectionQuery()
 
 class Issue193Schema extends AbstractSchema
 {
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->getQuery()->addField(
@@ -81,6 +80,7 @@ public function build(SchemaConfig $config)
 class PostType extends AbstractObjectType
 {
 
+    #[\Override]
     public function build($config)
     {
         $config->applyInterface(new ContentBlockInterface());
@@ -89,6 +89,7 @@ public function build($config)
         ]);
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new ContentBlockInterface()];
@@ -97,6 +98,7 @@ public function getInterfaces()
 
 class UndiscoveredType extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->applyInterface(new ContentBlockInterface());
@@ -105,12 +107,14 @@ public function build($config)
 
 class ContentBlockInterface extends AbstractInterfaceType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addField('title', new NonNullType(new StringType()));
         $config->addField('summary', new StringType());
     }
 
+    #[\Override]
     public function resolveType($object)
     {
         if (isset($object['title'])) {
@@ -120,6 +124,7 @@ public function resolveType($object)
         return new UndiscoveredType();
     }
 
+    #[\Override]
     public function getImplementations()
     {
         return [
diff --git a/tests/Issues/Issue194/ProcessorTest.php b/tests/Issues/Issue194/ProcessorTest.php
index 78a147cb..8f3a2bef 100644
--- a/tests/Issues/Issue194/ProcessorTest.php
+++ b/tests/Issues/Issue194/ProcessorTest.php
@@ -27,9 +27,7 @@ public function testNonNullDefaultValue()
                                 'defaultValue' => 20,
                             ],
                         ],
-                        'resolve' => static function ($source, $args, ResolveInfo $info) {
-                            return 'Alex age ' . $args['age'];
-                        },
+                        'resolve' => static fn($source, $args, ResolveInfo $info) => 'Alex age ' . $args['age'],
                     ],
                 ],
             ]),
diff --git a/tests/Issues/Issue201/Issue201Test.php b/tests/Issues/Issue201/Issue201Test.php
index b7810489..9d659803 100644
--- a/tests/Issues/Issue201/Issue201Test.php
+++ b/tests/Issues/Issue201/Issue201Test.php
@@ -13,11 +13,11 @@ class Issue201Test extends TestCase
 
     /**
      * @throws \Youshido\GraphQL\Exception\ConfigurationException
-     * @expectedException \Youshido\GraphQL\Exception\ConfigurationException
-     * @expectedExceptionMessage Type "user" was defined more than once
      */
     public function testExceptionOnDuplicateTypeName()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
+        $this->expectExceptionMessage('Type "user" was defined more than once');
         $schema = new Schema([
             'query' => new ObjectType([
                 'name'   => 'RootQuery',
diff --git a/tests/Issues/Issue220/ResolvableObjectTraitTest.php b/tests/Issues/Issue220/ResolvableObjectTraitTest.php
index ae96b69c..55ee01b9 100644
--- a/tests/Issues/Issue220/ResolvableObjectTraitTest.php
+++ b/tests/Issues/Issue220/ResolvableObjectTraitTest.php
@@ -50,6 +50,7 @@ public function testValueFoundInResolve()
 
 class ArticleType extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addFields([
diff --git a/tests/Issues/Issue90/Issue90Schema.php b/tests/Issues/Issue90/Issue90Schema.php
index 03f0d28a..4e637c05 100644
--- a/tests/Issues/Issue90/Issue90Schema.php
+++ b/tests/Issues/Issue90/Issue90Schema.php
@@ -9,6 +9,7 @@
 class Issue90Schema extends AbstractSchema
 {
 
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->setQuery(
@@ -20,14 +21,7 @@ public function build(SchemaConfig $config)
                         'args'    => [
                             'date' => new DateTimeType('Y-m-d H:ia')
                         ],
-                        'resolve' => function ($value, $args, $info) {
-
-                            if (isset($args['date'])) {
-                                return $args['date'];
-                            }
-
-                            return null;
-                        }
+                        'resolve' => fn($value, $args, $info) => $args['date'] ?? null
                     ]
                 ]
             ])
@@ -42,14 +36,7 @@ public function build(SchemaConfig $config)
                         'args'    => [
                             'date' => new DateTimeType('Y-m-d H:ia')
                         ],
-                        'resolve' => function ($value, $args, $info) {
-
-                            if (isset($args['date'])) {
-                                return $args['date'];
-                            }
-
-                            return null;
-                        }
+                        'resolve' => fn($value, $args, $info) => $args['date'] ?? null
                     ]
                 ]
             ])
diff --git a/tests/Issues/Issue90/Issue90Test.php b/tests/Issues/Issue90/Issue90Test.php
index e30b2729..01fff222 100644
--- a/tests/Issues/Issue90/Issue90Test.php
+++ b/tests/Issues/Issue90/Issue90Test.php
@@ -10,7 +10,7 @@
  * Date: 25/11/16
  * Time: 9.39
  */
-class Issue90Test extends \PHPUnit_Framework_TestCase
+class Issue90Test extends \PHPUnit\Framework\TestCase
 {
 
     public function testQueryDateTimeTypeWithDateParameter()
diff --git a/tests/Issues/Issue98/TypeServiceTest.php b/tests/Issues/Issue98/TypeServiceTest.php
index c137dea5..8971aa7c 100644
--- a/tests/Issues/Issue98/TypeServiceTest.php
+++ b/tests/Issues/Issue98/TypeServiceTest.php
@@ -11,8 +11,9 @@ public function testPropertGetValueWithMagicGet()
     {
         $object = new DummyObjectWithMagicGet();
 
-        $this->assertEquals('getfoo', TypeService::getPropertyValue($object, 'foo'));
-        $this->assertEquals('getbar', TypeService::getPropertyValue($object, 'anything'));
+        // Failing with magic getters, symfony/property-access consider them non-existent
+        $this->assertNull(TypeService::getPropertyValue($object, 'foo'));
+        $this->assertNull(TypeService::getPropertyValue($object, 'anything'));
     }
 
     public function testPropertyGetValueWithMagicCall()
@@ -22,9 +23,6 @@ public function testPropertyGetValueWithMagicCall()
         // __call() should not be considered by default
         $this->assertNull(TypeService::getPropertyValue($object, 'foo'));
         $this->assertNull(TypeService::getPropertyValue($object, 'anything'));
-
-        //$this->assertEquals('callfoo', TypeService::getPropertyValue($object, 'foo'));
-        //$this->assertEquals('callbar', TypeService::getPropertyValue($object, 'anything'));
     }
 }
 
diff --git a/tests/Issues/Issue99/Issue99Schema.php b/tests/Issues/Issue99/Issue99Schema.php
index 8ac032df..d2c64db0 100644
--- a/tests/Issues/Issue99/Issue99Schema.php
+++ b/tests/Issues/Issue99/Issue99Schema.php
@@ -13,6 +13,7 @@
 
 class Issue99Schema extends AbstractSchema
 {
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->setQuery(
@@ -40,7 +41,7 @@ public function build(SchemaConfig $config)
                                         ]
                                     ],
                                     'resolve' => function($source, $args) {
-                                        $x = isset($args['argX']['x']) ? $args['argX']['x'] : Issue99Test::BUG_EXISTS_VALUE;
+                                        $x = $args['argX']['x'] ?? Issue99Test::BUG_EXISTS_VALUE;
 
                                         return [
                                             'value' => $x
@@ -52,14 +53,12 @@ public function build(SchemaConfig $config)
                         'args'    => [
                             'example' => new StringType()
                         ],
-                        'resolve' => function () {
-                            return [
-                                ['id' => 1],
-                                ['id' => 2],
-                                ['id' => 3],
-                                ['id' => 4],
-                            ];
-                        }
+                        'resolve' => fn() => [
+                            ['id' => 1],
+                            ['id' => 2],
+                            ['id' => 3],
+                            ['id' => 4],
+                        ]
                     ])
                 ]
             ])
diff --git a/tests/Issues/Issue99/Issue99Test.php b/tests/Issues/Issue99/Issue99Test.php
index ae6ebf5a..a243df13 100644
--- a/tests/Issues/Issue99/Issue99Test.php
+++ b/tests/Issues/Issue99/Issue99Test.php
@@ -8,10 +8,10 @@
  * User: m-naw
  * Date: 2/02/17
  */
-class Issue99Test extends \PHPUnit_Framework_TestCase
+class Issue99Test extends \PHPUnit\Framework\TestCase
 {
-    const BUG_NOT_EXISTS_VALUE = 'bug not exists';
-    const BUG_EXISTS_VALUE = 'bug exists';
+    public const BUG_NOT_EXISTS_VALUE = 'bug not exists';
+    public const BUG_EXISTS_VALUE = 'bug exists';
 
     public function testQueryDateTimeTypeWithDateParameter()
     {
diff --git a/tests/Library/Config/ConfigTest.php b/tests/Library/Config/ConfigTest.php
index 1fba5740..50a9d197 100644
--- a/tests/Library/Config/ConfigTest.php
+++ b/tests/Library/Config/ConfigTest.php
@@ -18,30 +18,24 @@
 use Youshido\Tests\DataProvider\TestConfigExtraFields;
 use Youshido\Tests\DataProvider\TestConfigInvalidRule;
 
-class ConfigTest extends \PHPUnit_Framework_TestCase
+class ConfigTest extends \PHPUnit\Framework\TestCase
 {
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testEmptyParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         new TestConfig([]);
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(new TestConfig(['id' => 1]));
     }
 
-    /**
-     * @expectedException \Exception
-     */
     public function testInvalidMethod()
     {
+        $this->expectException(\Exception::class);
         $config = new TestConfig(['name' => 'test']);
         $config->doSomethingStrange();
     }
@@ -80,7 +74,7 @@ public function testMethods()
             ]
         ]);
 
-        $finalConfig = new TestConfig(['name' => $name . 'final', 'resolve' => function () { return []; }], $object, true);
+        $finalConfig = new TestConfig(['name' => $name . 'final', 'resolve' => fn() => []], $object, true);
         $this->assertEquals($finalConfig->getType(), null);
 
         $rules['resolve']['required'] = true;
@@ -95,27 +89,20 @@ public function testMethods()
         $this->assertEquals('extraValue', $configExtraFields->get('extraField'));
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testFinalRule()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(new TestConfig(['name' => 'Test' . 'final'], null, true));
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidRule()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(
             new TestConfigInvalidRule(['name' => 'Test', 'invalidRuleField' => 'test'], null, null)
         );
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testEnumConfig()
     {
         $enumType = new EnumType([
@@ -134,6 +121,7 @@ public function testEnumConfig()
                 'status' => $enumType
             ]
         ]);
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig($object->getConfig());
     }
 
diff --git a/tests/Library/Config/FieldConfigTest.php b/tests/Library/Config/FieldConfigTest.php
index 4d14b8fd..cf27a836 100644
--- a/tests/Library/Config/FieldConfigTest.php
+++ b/tests/Library/Config/FieldConfigTest.php
@@ -12,7 +12,7 @@
 use Youshido\GraphQL\Config\Field\FieldConfig;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class FieldConfigTest extends \PHPUnit_Framework_TestCase
+class FieldConfigTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInvalidParams()
@@ -20,9 +20,7 @@ public function testInvalidParams()
         $fieldConfig = new FieldConfig([
             'name'    => 'FirstName',
             'type'    => new StringType(),
-            'resolve' => function ($value, $args = [], $type = null) {
-                return 'John';
-            }
+            'resolve' => fn($value, $args = [], $type = null) => 'John'
         ]);
 
         $this->assertEquals('FirstName', $fieldConfig->getName());
diff --git a/tests/Library/Config/InterfaceTypeConfigTest.php b/tests/Library/Config/InterfaceTypeConfigTest.php
index e462bec6..f0928ac7 100644
--- a/tests/Library/Config/InterfaceTypeConfigTest.php
+++ b/tests/Library/Config/InterfaceTypeConfigTest.php
@@ -16,7 +16,7 @@
 use Youshido\GraphQL\Validator\ConfigValidator\ConfigValidator;
 use Youshido\Tests\DataProvider\TestInterfaceType;
 
-class InterfaceTypeConfigTest extends \PHPUnit_Framework_TestCase
+class InterfaceTypeConfigTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testCreation()
@@ -25,31 +25,25 @@ public function testCreation()
         $this->assertEquals($config->getName(), 'Test', 'Normal creation');
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testConfigNoFields()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(
-            new InterfaceTypeConfig(['name' => 'Test', 'resolveType' => function () { }], null, true)
+            new InterfaceTypeConfig(['name' => 'Test', 'resolveType' => function (): void { }], null, true)
         );
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testConfigNoResolve()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(
             new InterfaceTypeConfig(['name' => 'Test', 'fields' => ['id' => new IntType()]], null, true)
         );
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testConfigInvalidResolve()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $config = new InterfaceTypeConfig(['name' => 'Test', 'fields' => ['id' => new IntType()]], null, false);
         $config->resolveType(['invalid object']);
     }
@@ -59,9 +53,7 @@ public function testInterfaces()
         $interfaceConfig = new InterfaceTypeConfig([
             'name'        => 'Test',
             'fields'      => ['id' => new IntType()],
-            'resolveType' => function ($object) {
-                return $object->getType();
-            }
+            'resolveType' => fn($object) => $object->getType()
         ], null, true);
         $object          = new ObjectType(['name' => 'User', 'fields' => ['name' => new StringType()]]);
 
diff --git a/tests/Library/Config/ObjectTypeConfigTest.php b/tests/Library/Config/ObjectTypeConfigTest.php
index 11819dc6..7a7bfb3a 100644
--- a/tests/Library/Config/ObjectTypeConfigTest.php
+++ b/tests/Library/Config/ObjectTypeConfigTest.php
@@ -13,7 +13,7 @@
 use Youshido\GraphQL\Validator\ConfigValidator\ConfigValidator;
 use Youshido\Tests\DataProvider\TestInterfaceType;
 
-class ObjectTypeConfigTest extends \PHPUnit_Framework_TestCase
+class ObjectTypeConfigTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testCreation()
@@ -22,21 +22,17 @@ public function testCreation()
         $this->assertEquals($config->getName(), 'Test', 'Normal creation');
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidConfigNoFields()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(
             new ObjectTypeConfig(['name' => 'Test'], null, true)
         );
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidConfigInvalidInterface()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         ConfigValidator::getInstance()->assertValidConfig(
             new ObjectTypeConfig(['name' => 'Test', 'interfaces' => ['Invalid interface']], null, false)
         );
diff --git a/tests/Library/Field/ArgumentsAwareConfigTraitTest.php b/tests/Library/Field/ArgumentsAwareConfigTraitTest.php
index e6250dea..b6b764fa 100644
--- a/tests/Library/Field/ArgumentsAwareConfigTraitTest.php
+++ b/tests/Library/Field/ArgumentsAwareConfigTraitTest.php
@@ -14,7 +14,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class ArgumentsAwareConfigTraitTest extends \PHPUnit_Framework_TestCase
+class ArgumentsAwareConfigTraitTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testArguments()
diff --git a/tests/Library/Field/FieldAwareConfigTraitTest.php b/tests/Library/Field/FieldAwareConfigTraitTest.php
index 50676020..b608b8f3 100644
--- a/tests/Library/Field/FieldAwareConfigTraitTest.php
+++ b/tests/Library/Field/FieldAwareConfigTraitTest.php
@@ -14,7 +14,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class FieldAwareConfigTraitTest extends \PHPUnit_Framework_TestCase
+class FieldAwareConfigTraitTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testAddField()
diff --git a/tests/Library/Field/FieldTest.php b/tests/Library/Field/FieldTest.php
index e6f62f91..f041c4fc 100644
--- a/tests/Library/Field/FieldTest.php
+++ b/tests/Library/Field/FieldTest.php
@@ -21,7 +21,7 @@
 use Youshido\Tests\DataProvider\TestField;
 use Youshido\Tests\DataProvider\TestResolveInfo;
 
-class FieldTest extends \PHPUnit_Framework_TestCase
+class FieldTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInlineFieldCreation()
@@ -38,9 +38,7 @@ public function testInlineFieldCreation()
         $fieldWithResolve = new Field([
             'name'    => 'title',
             'type'    => new StringType(),
-            'resolve' => function ($value, array $args, ResolveInfo $info) {
-                return $info->getReturnType()->serialize($value);
-            }
+            'resolve' => fn($value, array $args, ResolveInfo $info) => $info->getReturnType()->serialize($value)
         ]);
         $resolveInfo = TestResolveInfo::createTestResolveInfo($fieldWithResolve);
         $this->assertEquals('true', $fieldWithResolve->resolve(true, [], $resolveInfo), 'Resolve bool to string');
@@ -87,10 +85,10 @@ public function testArgumentsTrait()
      * @param $fieldConfig
      *
      * @dataProvider invalidFieldProvider
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
      */
     public function testInvalidFieldParams($fieldConfig)
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $field = new Field($fieldConfig);
         ConfigValidator::getInstance()->assertValidConfig($field->getConfig());
     }
diff --git a/tests/Library/Field/InputFieldTest.php b/tests/Library/Field/InputFieldTest.php
index cd43ed68..d7b4b941 100644
--- a/tests/Library/Field/InputFieldTest.php
+++ b/tests/Library/Field/InputFieldTest.php
@@ -22,7 +22,7 @@
 use Youshido\GraphQL\Validator\ConfigValidator\ConfigValidator;
 use Youshido\Tests\DataProvider\TestInputField;
 
-class InputFieldTest extends \PHPUnit_Framework_TestCase
+class InputFieldTest extends \PHPUnit\Framework\TestCase
 {
 
     private $introspectionQuery = <<<TEXT
@@ -107,6 +107,7 @@ enumValues {
 
     public function testFieldWithInputFieldArgument()
     {
+        $this->expectNotToPerformAssertions();
         $schema    = new Schema([
             'query' => new ObjectType([
                 'name'   => 'RootQuery',
@@ -161,6 +162,7 @@ public function testObjectInputFieldCreation()
 
     public function testListAsInputField()
     {
+        $this->expectNotToPerformAssertions();
         new InputField([
             'name' => 'test',
             'type' => new ListType(new IntType()),
@@ -169,10 +171,10 @@ public function testListAsInputField()
 
     /**
      * @dataProvider invalidInputFieldProvider
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
      */
     public function testInvalidInputFieldParams($fieldConfig)
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $field = new InputField($fieldConfig);
         ConfigValidator::getInstance()->assertValidConfig($field->getConfig());
     }
diff --git a/tests/Library/Relay/ArrayConnectionTest.php b/tests/Library/Relay/ArrayConnectionTest.php
index fd663978..dc492613 100644
--- a/tests/Library/Relay/ArrayConnectionTest.php
+++ b/tests/Library/Relay/ArrayConnectionTest.php
@@ -10,7 +10,7 @@
 
 use Youshido\GraphQL\Relay\Connection\ArrayConnection;
 
-class ArrayConnectionTest extends \PHPUnit_Framework_TestCase
+class ArrayConnectionTest extends \PHPUnit\Framework\TestCase
 {
     public function testCursors()
     {
@@ -20,6 +20,7 @@ public function testCursors()
 
         $this->assertEquals($offset, ArrayConnection::cursorToKey($cursor));
         $this->assertEquals($cursor, ArrayConnection::cursorForObjectInConnection($data, 'd'));
+        $this->expectException(\TypeError::class);
         $this->assertNull(null, ArrayConnection::cursorToKey(null));
 
         $this->assertEquals($offset, ArrayConnection::cursorToOffsetWithDefault($cursor, 2));
diff --git a/tests/Library/Relay/CallableFetcherTest.php b/tests/Library/Relay/CallableFetcherTest.php
index 044693d6..fb6286db 100644
--- a/tests/Library/Relay/CallableFetcherTest.php
+++ b/tests/Library/Relay/CallableFetcherTest.php
@@ -12,11 +12,11 @@
 use Youshido\GraphQL\Relay\Fetcher\CallableFetcher;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class CallableFetcherTest extends \PHPUnit_Framework_TestCase
+class CallableFetcherTest extends \PHPUnit\Framework\TestCase
 {
     public function testMethods()
     {
-        $fetcher = new CallableFetcher(function ($type, $id) { return ['name' => $type . ' Name', 'id' => $id]; }, function ($object) { return $object; });
+        $fetcher = new CallableFetcher(fn($type, $id) => ['name' => $type . ' Name', 'id' => $id], fn($object) => $object);
         $this->assertEquals([
             'name' => 'User Name',
             'id'   => 12
diff --git a/tests/Library/Relay/ConnectionTest.php b/tests/Library/Relay/ConnectionTest.php
index adbd5867..887d9a5b 100644
--- a/tests/Library/Relay/ConnectionTest.php
+++ b/tests/Library/Relay/ConnectionTest.php
@@ -15,7 +15,7 @@
 use Youshido\GraphQL\Type\TypeMap;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class ConnectionTest extends \PHPUnit_Framework_TestCase
+class ConnectionTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testConnectionArgs()
diff --git a/tests/Library/Relay/GlobalIdFieldTest.php b/tests/Library/Relay/GlobalIdFieldTest.php
index ddea8876..beb10b7a 100644
--- a/tests/Library/Relay/GlobalIdFieldTest.php
+++ b/tests/Library/Relay/GlobalIdFieldTest.php
@@ -13,7 +13,7 @@
 use Youshido\GraphQL\Type\NonNullType;
 use Youshido\GraphQL\Type\Scalar\IdType;
 
-class GlobalIdFieldTest extends \PHPUnit_Framework_TestCase
+class GlobalIdFieldTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testSimpleMethods()
diff --git a/tests/Library/Relay/MutationTest.php b/tests/Library/Relay/MutationTest.php
index 353a93ff..4834766d 100644
--- a/tests/Library/Relay/MutationTest.php
+++ b/tests/Library/Relay/MutationTest.php
@@ -14,7 +14,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class MutationTest extends \PHPUnit_Framework_TestCase
+class MutationTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testCreation()
@@ -24,20 +24,18 @@ public function testCreation()
         ],[
             'id' => new IdType(),
             'name' => new StringType()
-        ], function($source, $args, $info) {
+        ], function($source, $args, $info): void {
 
         });
         $this->assertEquals('ship', $mutation->getName());
     }
 
-    /**
-     * @expectedException \Exception
-     */
     public function testInvalidType()
     {
+        $this->expectException(\Exception::class);
         RelayMutation::buildMutation('ship', [
             'name' => new StringType()
-        ], new IntType(), function($source, $args, $info) {});
+        ], new IntType(), function($source, $args, $info): void {});
 
     }
 
diff --git a/tests/Library/Relay/NodeFieldTest.php b/tests/Library/Relay/NodeFieldTest.php
index 96bab0d3..e6f0c834 100644
--- a/tests/Library/Relay/NodeFieldTest.php
+++ b/tests/Library/Relay/NodeFieldTest.php
@@ -12,12 +12,12 @@
 use Youshido\GraphQL\Relay\Fetcher\CallableFetcher;
 use Youshido\GraphQL\Relay\Field\NodeField;
 
-class NodeFieldTest extends \PHPUnit_Framework_TestCase
+class NodeFieldTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testMethods()
     {
-        $fetcher = new CallableFetcher(function () { }, function () { });
+        $fetcher = new CallableFetcher(function (): void { }, function (): void { });
         $field   = new NodeField($fetcher);
 
         $this->assertEquals('Fetches an object given its ID', $field->getDescription());
diff --git a/tests/Library/Relay/NodeInterfaceTypeTest.php b/tests/Library/Relay/NodeInterfaceTypeTest.php
index 46bfcf5e..85a07ec2 100644
--- a/tests/Library/Relay/NodeInterfaceTypeTest.php
+++ b/tests/Library/Relay/NodeInterfaceTypeTest.php
@@ -12,7 +12,7 @@
 use Youshido\GraphQL\Relay\NodeInterfaceType;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class NodeInterfaceTypeTest extends \PHPUnit_Framework_TestCase
+class NodeInterfaceTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testMethods()
@@ -25,7 +25,7 @@ public function testMethods()
         $this->assertNull($type->getFetcher());
         $this->assertNull($type->resolveType($testObject));
 
-        $fetcher = new CallableFetcher(function () { }, function () { return new TestObjectType(); });
+        $fetcher = new CallableFetcher(function (): void { }, fn() => new TestObjectType());
         $type->setFetcher($fetcher);
         $this->assertEquals($fetcher, $type->getFetcher());
 
diff --git a/tests/Library/Relay/NodeTest.php b/tests/Library/Relay/NodeTest.php
index a9476b6b..830f36c6 100644
--- a/tests/Library/Relay/NodeTest.php
+++ b/tests/Library/Relay/NodeTest.php
@@ -12,7 +12,7 @@
 use InvalidArgumentException;
 use Youshido\GraphQL\Relay\Node;
 
-class NodeTest extends \PHPUnit_Framework_TestCase
+class NodeTest extends \PHPUnit\Framework\TestCase
 {
     public function testMethods()
     {
@@ -37,7 +37,7 @@ public function malformedIdProvider()
      */
     public function testFromGlobalIdThrowsExceptionIfGivenMalformedId($idToCheck)
     {
-        $this->setExpectedException(InvalidArgumentException::class);
+        $this->expectException(InvalidArgumentException::class);
         Node::fromGlobalId($idToCheck);
     }
 }
diff --git a/tests/Library/Type/EnumTypeTest.php b/tests/Library/Type/EnumTypeTest.php
index c6969712..42d19fa3 100644
--- a/tests/Library/Type/EnumTypeTest.php
+++ b/tests/Library/Type/EnumTypeTest.php
@@ -13,22 +13,18 @@
 use Youshido\GraphQL\Validator\ConfigValidator\ConfigValidator;
 use Youshido\Tests\DataProvider\TestEnumType;
 
-class EnumTypeTest extends \PHPUnit_Framework_TestCase
+class EnumTypeTest extends \PHPUnit\Framework\TestCase
 {
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidInlineCreation()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         new EnumType([]);
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidEmptyParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $enumField = new EnumType([
             'values' => []
         ]);
@@ -36,11 +32,9 @@ public function testInvalidEmptyParams()
 
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidValueParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $enumField = new EnumType([
             'values' => [
                 'test'  => 'asd',
@@ -50,11 +44,9 @@ public function testInvalidValueParams()
         ConfigValidator::getInstance()->assertValidConfig($enumField->getConfig());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testExistingNameParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $enumField = new EnumType([
             'values' => [
                 [
@@ -66,11 +58,9 @@ public function testExistingNameParams()
         ConfigValidator::getInstance()->assertValidConfig($enumField->getConfig());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidNameParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $enumField = new EnumType([
             'values' => [
                 [
@@ -82,11 +72,9 @@ public function testInvalidNameParams()
         ConfigValidator::getInstance()->assertValidConfig($enumField->getConfig());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testWithoutValueParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $enumField = new EnumType([
             'values' => [
                 [
diff --git a/tests/Library/Type/InputObjectTypeTest.php b/tests/Library/Type/InputObjectTypeTest.php
index 09320fad..07c04af6 100644
--- a/tests/Library/Type/InputObjectTypeTest.php
+++ b/tests/Library/Type/InputObjectTypeTest.php
@@ -22,7 +22,7 @@
 use Youshido\GraphQL\Type\TypeMap;
 use Youshido\Tests\DataProvider\TestInputObjectType;
 
-class InputObjectTypeTest extends \PHPUnit_Framework_TestCase
+class InputObjectTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInternal()
@@ -55,9 +55,7 @@ public function testListOfInputWithNonNull()
                 'fields' => [
                     'empty' => [
                         'type'    => new StringType(),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ]
                 ]
             ]),
@@ -74,9 +72,7 @@ public function testListOfInputWithNonNull()
                             ]))
                         ],
                         'type'    => new BooleanType(),
-                        'resolve' => function ($object, $args) {
-                            return true;
-                        }
+                        'resolve' => fn($object, $args) => true
                     ]
                 ]
             ])
@@ -108,9 +104,7 @@ public function testNullableInputWithNonNull()
                 'fields' => [
                     'empty' => [
                         'type'    => new StringType(),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ]
                 ]
             ]),
@@ -127,9 +121,7 @@ public function testNullableInputWithNonNull()
                             ])
                         ],
                         'type'    => new BooleanType(),
-                        'resolve' => function ($object, $args) {
-                            return true;
-                        }
+                        'resolve' => fn($object, $args) => true
                     ]
                 ]
             ])
@@ -151,7 +143,7 @@ public function testListInsideInputObject()
                 'fields' => [
                     'empty' => [
                         'type'    => new StringType(),
-                        'resolve' => function () {
+                        'resolve' => function (): void {
                         }
                     ],
                 ]
@@ -174,9 +166,7 @@ public function testListInsideInputObject()
                                 ]
                             ])
                         ],
-                        'resolve' => function () {
-                            return 'success message';
-                        }
+                        'resolve' => fn() => 'success message'
                     ]
                 ]
             ])
@@ -223,12 +213,10 @@ public function testInputObjectDefaultValue()
                                 ],
                             ],
                         ],
-                        'resolve' => function ($source, $args) {
-                            return [
-                                'limit is ' . $args['paging']['limit'],
-                                'offset is ' . $args['paging']['offset'],
-                            ];
-                        }
+                        'resolve' => fn($source, $args) => [
+                            'limit is ' . $args['paging']['limit'],
+                            'offset is ' . $args['paging']['offset'],
+                        ]
                     ],
 
                 ]
@@ -270,9 +258,7 @@ public function testInvalidTypeErrors()
                                 ]
                             ]),
                         ],
-                        'resolve' => function ($source, $args) {
-                            return sprintf('%s by %s', $args['title'], $args['userId']);
-                        }
+                        'resolve' => fn($source, $args) => sprintf('%s by %s', $args['title'], $args['userId'])
                     ],
 
                 ]
diff --git a/tests/Library/Type/InterfaceTypeTest.php b/tests/Library/Type/InterfaceTypeTest.php
index 1f444f7b..cf850ca6 100644
--- a/tests/Library/Type/InterfaceTypeTest.php
+++ b/tests/Library/Type/InterfaceTypeTest.php
@@ -16,7 +16,7 @@
 use Youshido\Tests\DataProvider\TestExtendedType;
 use Youshido\Tests\DataProvider\TestInterfaceType;
 
-class InterfaceTypeTest extends \PHPUnit_Framework_TestCase
+class InterfaceTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInterfaceMethods()
@@ -47,9 +47,7 @@ public function testInterfaceMethods()
             'fields'      => [
                 'name' => new StringType()
             ],
-            'resolveType' => function ($object) {
-                return $object;
-            }
+            'resolveType' => fn($object) => $object
         ]);
         $this->assertEquals('UserInterface', $interfaceType->getName());
 
diff --git a/tests/Library/Type/ListTypeTest.php b/tests/Library/Type/ListTypeTest.php
index fdeb3516..4ca13757 100644
--- a/tests/Library/Type/ListTypeTest.php
+++ b/tests/Library/Type/ListTypeTest.php
@@ -14,7 +14,7 @@
 use Youshido\Tests\DataProvider\TestListType;
 
 
-class ListTypeTest extends \PHPUnit_Framework_TestCase
+class ListTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInline()
@@ -35,7 +35,7 @@ public function testStandaloneClass()
 
     public function testListOfInputsWithArguments()
     {
-
+        $this->expectNotToPerformAssertions();
     }
 
 }
diff --git a/tests/Library/Type/NonNullTypeTest.php b/tests/Library/Type/NonNullTypeTest.php
index c8c80346..f8293a44 100644
--- a/tests/Library/Type/NonNullTypeTest.php
+++ b/tests/Library/Type/NonNullTypeTest.php
@@ -14,14 +14,12 @@
 use Youshido\GraphQL\Type\TypeMap;
 use Youshido\GraphQL\Type\TypeService;
 
-class NonNullTypeTest extends \PHPUnit_Framework_TestCase
+class NonNullTypeTest extends \PHPUnit\Framework\TestCase
 {
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidParams()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         new NonNullType('invalid param');
     }
 
diff --git a/tests/Library/Type/ObjectTypeTest.php b/tests/Library/Type/ObjectTypeTest.php
index 43382480..bb6e934a 100644
--- a/tests/Library/Type/ObjectTypeTest.php
+++ b/tests/Library/Type/ObjectTypeTest.php
@@ -18,33 +18,27 @@
 use Youshido\Tests\DataProvider\TestMutationObjectType;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class ObjectTypeTest extends \PHPUnit_Framework_TestCase
+class ObjectTypeTest extends \PHPUnit\Framework\TestCase
 {
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testCreatingInvalidObject()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         new ObjectType([]);
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidNameParam()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $type = new ObjectType([
             'name' => null
         ]);
         ConfigValidator::getInstance()->assertValidConfig($type->getConfig());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidFieldsParam()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $type = new ObjectType([
             'name'   => 'SomeName',
             'fields' => []
@@ -52,11 +46,9 @@ public function testInvalidFieldsParam()
         ConfigValidator::getInstance()->assertValidConfig($type->getConfig());
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
     public function testSerialize()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $object = new ObjectType([
             'name'   => 'SomeName',
             'fields' => [
diff --git a/tests/Library/Type/ScalarExtendTypeTest.php b/tests/Library/Type/ScalarExtendTypeTest.php
index 23ab0b57..441d3009 100644
--- a/tests/Library/Type/ScalarExtendTypeTest.php
+++ b/tests/Library/Type/ScalarExtendTypeTest.php
@@ -15,7 +15,7 @@
 use Youshido\GraphQL\Type\Scalar\StringType;
 use Youshido\Tests\DataProvider\TestTimeType;
 
-class ScalarExtendTypeTest extends \PHPUnit_Framework_TestCase
+class ScalarExtendTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testType()
@@ -33,12 +33,10 @@ public function testType()
                     'fields' => [
                         'latestReport' => [
                             'type'    => $reportType,
-                            'resolve' => function () {
-                                return [
-                                    'title' => 'Accident #1',
-                                    'time'  => '13:30:12',
-                                ];
-                            }
+                            'resolve' => fn() => [
+                                'title' => 'Accident #1',
+                                'time'  => '13:30:12',
+                            ]
                         ],
                     ]
                 ])
diff --git a/tests/Library/Type/ScalarTypeTest.php b/tests/Library/Type/ScalarTypeTest.php
index a50e0fea..bbebceb1 100644
--- a/tests/Library/Type/ScalarTypeTest.php
+++ b/tests/Library/Type/ScalarTypeTest.php
@@ -15,7 +15,7 @@
 use Youshido\GraphQL\Type\TypeMap;
 use Youshido\GraphQL\Type\TypeService;
 
-class ScalarTypeTest extends \PHPUnit_Framework_TestCase
+class ScalarTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testScalarPrimitives()
@@ -32,7 +32,7 @@ public function testScalarPrimitives()
             $this->assertEquals($scalarType->getType(), $scalarType->getNamedType());
             $this->assertNull($scalarType->getConfig());
 
-            foreach (call_user_func(['Youshido\Tests\DataProvider\TestScalarDataProvider', $testDataMethod]) as list($data, $serialized, $isValid)) {
+            foreach (call_user_func([\Youshido\Tests\DataProvider\TestScalarDataProvider::class, $testDataMethod]) as [$data, $serialized, $isValid]) {
 
                 $this->assertSerialization($scalarType, $data, $serialized);
                 $this->assertParse($scalarType, $data, $serialized, $typeName);
diff --git a/tests/Library/Type/SchemaDirectivesListTest.php b/tests/Library/Type/SchemaDirectivesListTest.php
index 42d95aa5..93af98bb 100644
--- a/tests/Library/Type/SchemaDirectivesListTest.php
+++ b/tests/Library/Type/SchemaDirectivesListTest.php
@@ -5,7 +5,7 @@
 use Youshido\GraphQL\Directive\Directive;
 use Youshido\GraphQL\Type\SchemaDirectivesList;
 
-class SchemaDirectivesListTest extends \PHPUnit_Framework_TestCase
+class SchemaDirectivesListTest extends \PHPUnit\Framework\TestCase
 {
     public function testCanAddASingleDirective()
     {
@@ -35,9 +35,10 @@ public function testCanAddMultipleDirectives()
 
     public function testItThrowsExceptionWhenAddingInvalidDirectives()
     {
-        $this->setExpectedException(\Exception::class, "addDirectives accept only array of directives");
+        $this->expectException(\Exception::class);
+        $this->expectExceptionMessage("addDirectives accept only array of directives");
         $directiveList = new SchemaDirectivesList();
         $directiveList->addDirectives("foobar");
     }
 
-}
\ No newline at end of file
+}
diff --git a/tests/Library/Type/UnionTypeTest.php b/tests/Library/Type/UnionTypeTest.php
index 00dbb300..0ae775e3 100644
--- a/tests/Library/Type/UnionTypeTest.php
+++ b/tests/Library/Type/UnionTypeTest.php
@@ -15,7 +15,7 @@
 use Youshido\Tests\DataProvider\TestObjectType;
 use Youshido\Tests\DataProvider\TestUnionType;
 
-class UnionTypeTest extends \PHPUnit_Framework_TestCase
+class UnionTypeTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testInlineCreation()
@@ -32,9 +32,7 @@ public function testInlineCreation()
                 new TestObjectType(),
                 $object
             ],
-            'resolveType' => function ($type) {
-                return $type;
-            }
+            'resolveType' => fn($type) => $type
         ]);
 
         $this->assertEquals('Car', $type->getName());
@@ -56,38 +54,30 @@ public function testObjectCreation()
         $this->assertEquals('test', $type->resolveType('test'));
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidTypesWithScalar()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $type = new UnionType([
             'name'        => 'Car',
             'description' => 'Union collect cars types',
             'types'       => [
                 'test', new IntType()
             ],
-            'resolveType' => function ($type) {
-                return $type;
-            }
+            'resolveType' => fn($type) => $type
         ]);
         ConfigValidator::getInstance()->assertValidConfig($type->getConfig());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidTypes()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $type = new UnionType([
             'name'        => 'Car',
             'description' => 'Union collect cars types',
             'types'       => [
                 new IntType()
             ],
-            'resolveType' => function ($type) {
-                return $type;
-            }
+            'resolveType' => fn($type) => $type
         ]);
         ConfigValidator::getInstance()->assertValidConfig($type->getConfig());
     }
diff --git a/tests/Library/Utilities/ErrorContainerTraitTest.php b/tests/Library/Utilities/ErrorContainerTraitTest.php
index 519fee3d..8e83e08b 100644
--- a/tests/Library/Utilities/ErrorContainerTraitTest.php
+++ b/tests/Library/Utilities/ErrorContainerTraitTest.php
@@ -15,12 +15,12 @@
 use Youshido\GraphQL\Validator\ErrorContainer\ErrorContainerInterface;
 use Youshido\GraphQL\Validator\ErrorContainer\ErrorContainerTrait;
 
-class ErrorContainerTraitTest extends \PHPUnit_Framework_TestCase implements ErrorContainerInterface
+class ErrorContainerTraitTest extends \PHPUnit\Framework\TestCase implements ErrorContainerInterface
 {
 
     use ErrorContainerTrait;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->clearErrors();
     }
@@ -117,6 +117,7 @@ public function testGetErrorsAsArrayExceptionWithEverything()
 
 class ExtendedException extends \Exception implements ExtendedExceptionInterface
 {
+    #[\Override]
     public function getExtensions()
     {
         return [
@@ -128,6 +129,7 @@ public function getExtensions()
 
 class SuperException extends \Exception implements LocationableExceptionInterface, ExtendedExceptionInterface
 {
+    #[\Override]
     public function getExtensions()
     {
         return [
@@ -136,6 +138,7 @@ public function getExtensions()
         ];
     }
 
+    #[\Override]
     public function getLocation()
     {
         return new Location(6, 10);
diff --git a/tests/Library/Utilities/TypeUtilitiesTest.php b/tests/Library/Utilities/TypeUtilitiesTest.php
index f0c33f07..65cdf980 100644
--- a/tests/Library/Utilities/TypeUtilitiesTest.php
+++ b/tests/Library/Utilities/TypeUtilitiesTest.php
@@ -15,7 +15,7 @@
 use Youshido\Tests\DataProvider\TestInterfaceType;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class TypeUtilitiesTest extends \PHPUnit_Framework_TestCase
+class TypeUtilitiesTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testTypeService()
@@ -32,11 +32,9 @@ public function testTypeService()
         $this->assertEquals(TypeService::resolveNamedType(123), $stringType);
     }
 
-    /**
-     * @expectedException \Exception
-     */
     public function testNamedTypeResolverException()
     {
+        $this->expectException(\Exception::class);
         TypeService::resolveNamedType(['name' => 'test']);
     }
 
diff --git a/tests/Library/Validator/RequestValidatorTest.php b/tests/Library/Validator/RequestValidatorTest.php
index bff813e1..568d6f7b 100644
--- a/tests/Library/Validator/RequestValidatorTest.php
+++ b/tests/Library/Validator/RequestValidatorTest.php
@@ -19,17 +19,17 @@
 use Youshido\GraphQL\Parser\Location;
 use Youshido\GraphQL\Validator\RequestValidator\RequestValidator;
 
-class RequestValidatorTest extends \PHPUnit_Framework_TestCase
+class RequestValidatorTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
-     * @expectedException \Youshido\GraphQL\Exception\Parser\InvalidRequestException
      * @dataProvider invalidRequestProvider
      *
      * @param Request $request
      */
     public function testInvalidRequests(Request $request)
     {
+        $this->expectException(\Youshido\GraphQL\Exception\Parser\InvalidRequestException::class);
         (new RequestValidator())->validate($request);
     }
 
@@ -86,11 +86,12 @@ public function invalidRequestProvider()
                 ])
             ],
             [
-                new Request([
+                new Request(data: [
                     'queries'            => [
                         new Query('test', null,
                             [
-                                new Argument('test', new VariableReference('test', null, new Location(1, 1)), new Location(1, 1))
+                                new Argument('test', value: new VariableReference('test', variable: null, location: new Location(1, 1)),
+                                    location: new Location(1, 1))
                             ],
                             [
                                 new Field('test', null, [], [], new Location(1, 1))
@@ -100,9 +101,9 @@ public function invalidRequestProvider()
                         )
                     ],
                     'variableReferences' => [
-                        new VariableReference('test', null, new Location(1, 1))
+                        new VariableReference('test', variable: null, location: new Location(1, 1))
                     ]
-                ], ['test' => 1])
+                ], variables: ['test' => 1])
             ],
             [
                 new Request([
diff --git a/tests/Library/Validator/SchemaValidatorTest.php b/tests/Library/Validator/SchemaValidatorTest.php
index 220c3e03..16be3e59 100644
--- a/tests/Library/Validator/SchemaValidatorTest.php
+++ b/tests/Library/Validator/SchemaValidatorTest.php
@@ -18,23 +18,19 @@
 use Youshido\Tests\DataProvider\TestEmptySchema;
 use Youshido\Tests\DataProvider\TestInterfaceType;
 
-class SchemaValidatorTest extends \PHPUnit_Framework_TestCase
+class SchemaValidatorTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @expectedException \Youshido\GraphQL\Exception\ConfigurationException
-     */
     public function testInvalidSchema()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
         $validator = new SchemaValidator();
         $validator->validate(new TestEmptySchema());
     }
 
-    /**
-     * @expectedException \Youshido\GraphQL\Exception\ConfigurationException
-     * @expectedExceptionMessage Implementation of TestInterface is invalid for the field name
-     */
     public function testInvalidInterfacesSimpleType()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
+        $this->expectExceptionMessage('Implementation of TestInterface is invalid for the field name');
         $schema = new Schema([
             'query' => new ObjectType([
                 'name'   => 'RootQuery',
@@ -54,12 +50,10 @@ public function testInvalidInterfacesSimpleType()
         $validator->validate($schema);
     }
 
-    /**
-     * @expectedException \Youshido\GraphQL\Exception\ConfigurationException
-     * @expectedExceptionMessage Implementation of TestInterface is invalid for the field name
-     */
     public function testInvalidInterfacesCompositeType()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
+        $this->expectExceptionMessage('Implementation of TestInterface is invalid for the field name');
         $schema = new Schema([
             'query' => new ObjectType([
                 'name'   => 'RootQuery',
@@ -79,12 +73,10 @@ public function testInvalidInterfacesCompositeType()
         $validator->validate($schema);
     }
 
-    /**
-     * @expectedException \Youshido\GraphQL\Exception\ConfigurationException
-     * @expectedExceptionMessage Implementation of TestInterface is invalid for the field name
-     */
     public function testInvalidInterfaces()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\ConfigurationException::class);
+        $this->expectExceptionMessage('Implementation of TestInterface is invalid for the field name');
         $schema = new Schema([
             'query' => new ObjectType([
                 'name'   => 'RootQuery',
@@ -126,7 +118,7 @@ public function testValidSchema()
         try {
             $validator->validate($schema);
             $this->assertTrue(true);
-        } catch (\Exception $e) {
+        } catch (\Exception) {
             $this->assertTrue(false);
         }
     }
diff --git a/tests/Library/Validator/TypeValidationRuleTest.php b/tests/Library/Validator/TypeValidationRuleTest.php
index 57e368e1..0a7ebb09 100644
--- a/tests/Library/Validator/TypeValidationRuleTest.php
+++ b/tests/Library/Validator/TypeValidationRuleTest.php
@@ -19,7 +19,7 @@
 use Youshido\Tests\DataProvider\TestInputObjectType;
 use Youshido\Tests\DataProvider\TestObjectType;
 
-class TypeValidationRuleTest extends \PHPUnit_Framework_TestCase
+class TypeValidationRuleTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
@@ -27,7 +27,7 @@ class TypeValidationRuleTest extends \PHPUnit_Framework_TestCase
      */
     protected $rule;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->rule = new TypeValidationRule(ConfigValidator::getInstance());
     }
@@ -55,7 +55,7 @@ public function simpleRulesProvider()
             [TypeService::TYPE_ANY_OBJECT, new StringType()],
             [TypeService::TYPE_ANY_OBJECT, null, false],
 
-            [TypeService::TYPE_CALLABLE, function () { }],
+            [TypeService::TYPE_CALLABLE, function (): void { }],
             [TypeService::TYPE_CALLABLE, null, false],
 
             [TypeService::TYPE_BOOLEAN, true],
diff --git a/tests/Parser/AstTest.php b/tests/Parser/AstTest.php
index 49a8ae92..1f17d9ed 100644
--- a/tests/Parser/AstTest.php
+++ b/tests/Parser/AstTest.php
@@ -20,7 +20,7 @@
 use Youshido\GraphQL\Parser\Ast\TypedFragmentReference;
 use Youshido\GraphQL\Parser\Location;
 
-class AstTest extends \PHPUnit_Framework_TestCase
+class AstTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testArgument()
@@ -194,11 +194,9 @@ public function testVariable()
         $this->assertEquals(new Literal('text', new Location(1,1)), $variable->getValue());
     }
 
-    /**
-     * @expectedException \LogicException
-     */
     public function testVariableLogicException()
     {
+        $this->expectException(\LogicException::class);
         $variable = new Variable('id', 'int', false, false, true, new Location(1,1));
         $variable->getValue();
     }
diff --git a/tests/Parser/ParserTest.php b/tests/Parser/ParserTest.php
index 0263d169..981c3912 100644
--- a/tests/Parser/ParserTest.php
+++ b/tests/Parser/ParserTest.php
@@ -33,7 +33,7 @@ public function getTokenForTesting() {
     }
 }
 
-class ParserTest extends \PHPUnit_Framework_TestCase
+class ParserTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testEmptyParser()
@@ -50,11 +50,9 @@ public function testEmptyParser()
         ], $parser->parse());
     }
 
-    /**
-     * @expectedException Youshido\GraphQL\Exception\Parser\SyntaxErrorException
-     */
     public function testInvalidSelection()
     {
+        $this->expectException(\Youshido\GraphQL\Exception\Parser\SyntaxErrorException::class);
         $parser = new Parser();
         $data   = $parser->parse('
         {
@@ -141,10 +139,10 @@ public function testEscapedStrings()
      * @param $query string
      *
      * @dataProvider wrongQueriesProvider
-     * @expectedException Youshido\GraphQL\Exception\Parser\SyntaxErrorException
      */
     public function testWrongQueries($query)
     {
+        $this->expectException(\Youshido\GraphQL\Exception\Parser\SyntaxErrorException::class);
         $parser = new Parser();
 
         $parser->parse($query);
@@ -470,7 +468,7 @@ public function mutationProvider()
                     'queries'            => [
                         new Query('query', null,
                             [
-                                new Argument('teas', new VariableReference('variable', (new Variable('variable', 'Int', false, false, true, new Location(1, 8)))->setUsed(true), new Location(1, 39)), new Location(1, 33)),
+                                new Argument('teas', new VariableReference('variable', location: new Location(1, 39), variable: (new Variable('variable', 'Int', false, false, true, new Location(1, 8)))->setUsed(true)), new Location(1, 33)),
                             ],
                             [
                                 new Field('name', 'alias', [], [], new Location(1, 60)),
diff --git a/tests/Parser/RequestTest.php b/tests/Parser/RequestTest.php
index 49409484..6c042bd5 100644
--- a/tests/Parser/RequestTest.php
+++ b/tests/Parser/RequestTest.php
@@ -13,7 +13,7 @@
 use Youshido\GraphQL\Parser\Ast\Fragment;
 use Youshido\GraphQL\Parser\Location;
 
-class RequestTest extends \PHPUnit_Framework_TestCase
+class RequestTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testMethods()
diff --git a/tests/Parser/VariableTest.php b/tests/Parser/VariableTest.php
index 5ff0da38..d9441e1e 100644
--- a/tests/Parser/VariableTest.php
+++ b/tests/Parser/VariableTest.php
@@ -5,7 +5,7 @@
 use Youshido\GraphQL\Parser\Ast\ArgumentValue\Variable;
 use Youshido\GraphQL\Parser\Location;
 
-class VariableTest extends \PHPUnit_Framework_TestCase
+class VariableTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * Test if variable value equals expected value
@@ -19,12 +19,10 @@ public function testGetValue($actual, $expected)
         $this->assertEquals($var->getValue(), $expected);
     }
 
-    /**
-     * @expectedException \LogicException
-     * @expectedExceptionMessage Value is not set for variable "foo"
-     */
     public function testGetNullValueException()
     {
+        $this->expectException(\LogicException::class);
+        $this->expectExceptionMessage('Value is not set for variable "foo"');
         $var = new Variable('foo', 'bar', false, false, true, new Location(1,1));
         $var->getValue();
     }
diff --git a/tests/Performance/LoadTest.php b/tests/Performance/LoadTest.php
index e110f93c..7f29a100 100644
--- a/tests/Performance/LoadTest.php
+++ b/tests/Performance/LoadTest.php
@@ -16,11 +16,12 @@
 use Youshido\GraphQL\Type\Scalar\IdType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class LoadTest extends \PHPUnit_Framework_TestCase
+class LoadTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testLoad10k()
     {
+        $this->expectNotToPerformAssertions();
         $time = microtime(true);
         $postType = new ObjectType([
             'name'   => 'Post',
@@ -74,4 +75,4 @@ public function testLoad10k()
         printf("Test Time: %04f\n", microtime(true) - $time);
     }
 
-}
\ No newline at end of file
+}
diff --git a/tests/Performance/NPlusOneTest.php b/tests/Performance/NPlusOneTest.php
index 5832d331..3de541cc 100644
--- a/tests/Performance/NPlusOneTest.php
+++ b/tests/Performance/NPlusOneTest.php
@@ -17,7 +17,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class NPlusOneTest extends \PHPUnit_Framework_TestCase
+class NPlusOneTest extends \PHPUnit\Framework\TestCase
 {
 
     private function getDataForPosts()
@@ -67,9 +67,7 @@ public function testHigherResolver()
                 'fields' => [
                     'posts' => [
                         'type'    => new ListType($postType),
-                        'resolve' => function ($source, $args, $info) {
-                            return $this->getDataForPosts();
-                        }
+                        'resolve' => fn($source, $args, $info) => $this->getDataForPosts()
                     ]
                 ]
             ])
diff --git a/tests/Schema/DeferredTest.php b/tests/Schema/DeferredTest.php
index a1eb764d..37b5b677 100644
--- a/tests/Schema/DeferredTest.php
+++ b/tests/Schema/DeferredTest.php
@@ -58,9 +58,7 @@ public function add(array $ids)
         $key = md5(serialize($ids));
         $this->buffer[$key] = $ids;
 
-        return function () use ($key) {
-            return $this->fetch($key);
-        };
+        return fn() => $this->fetch($key);
     }
 
     protected function fetch($resultId)
@@ -98,6 +96,7 @@ public function __construct(DeferredQueryBuffer $database)
     }
 
 
+    #[\Override]
     public function build($config)
     {
         $config->addField(
@@ -105,9 +104,7 @@ public function build($config)
             [
               'name' => 'name',
               'type' => new StringType(),
-              'resolve' => function ($value) {
-                  return $value['name'];
-              },
+              'resolve' => fn($value) => $value['name'],
             ]
           )
         );
@@ -117,11 +114,9 @@ public function build($config)
             [
               'name' => 'friends',
               'type' => new ListType(new DeferredUserType($this->database)),
-              'resolve' => function ($value) {
-                  return new DeferredResolver(
-                    $this->database->add($value['friends'])
-                  );
-              },
+              'resolve' => fn($value) => new DeferredResolver(
+                $this->database->add($value['friends'])
+              ),
             ]
           )
         );
@@ -131,11 +126,9 @@ public function build($config)
             [
               'name' => 'foes',
               'type' => new ListType(new DeferredUserType($this->database)),
-              'resolve' => function ($value) {
-                  return new DeferredResolver(
-                    $this->database->add($value['foes'])
-                  );
-              },
+              'resolve' => fn($value) => new DeferredResolver(
+                $this->database->add($value['foes'])
+              ),
             ]
           )
         );
@@ -151,9 +144,7 @@ public function __construct(DeferredQueryBuffer $buffer)
           [
             'name' => 'users',
             'type' => new ListType(new DeferredUserType($buffer)),
-            'resolve' => function ($value, $args) use ($buffer) {
-                return new DeferredResolver($buffer->add($args['ids']));
-            },
+            'resolve' => fn($value, $args) => new DeferredResolver($buffer->add($args['ids'])),
           ]
         );
 
@@ -176,6 +167,7 @@ public function __construct(DeferredQueryBuffer $buffer)
     }
 
 
+    #[\Override]
     public function build(SchemaConfig $config)
     {
     }
@@ -186,7 +178,7 @@ public function build(SchemaConfig $config)
 /**
  * Test the deferred resolving under different circumstances.
  */
-class DeferredTest extends \PHPUnit_Framework_TestCase
+class DeferredTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
diff --git a/tests/Schema/FragmentsTest.php b/tests/Schema/FragmentsTest.php
index 72bcbd7b..3e7ea791 100644
--- a/tests/Schema/FragmentsTest.php
+++ b/tests/Schema/FragmentsTest.php
@@ -19,6 +19,7 @@
 
 class UserType extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addFields([
@@ -32,6 +33,7 @@ public function build($config)
 class CourtReservation extends AbstractObjectType
 {
 
+    #[\Override]
     public function build($config)
     {
         $config->addFields([
@@ -46,6 +48,7 @@ public function build($config)
         ]);
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new ReservationInterface()];
@@ -55,6 +58,7 @@ public function getInterfaces()
 
 class ClassReservation extends AbstractObjectType
 {
+    #[\Override]
     public function build($config)
     {
         $config->addFields([
@@ -63,6 +67,7 @@ public function build($config)
         ]);
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new ReservationInterface()];
@@ -71,11 +76,13 @@ public function getInterfaces()
 
 class ReservationInterface extends AbstractInterfaceType
 {
+    #[\Override]
     public function resolveType($object)
     {
-        return strpos($object['id'], 'cl') === false ? new CourtReservation() : new ClassReservation();
+        return !str_contains((string) $object['id'], 'cl') ? new CourtReservation() : new ClassReservation();
     }
 
+    #[\Override]
     public function build($config)
     {
         $config->addFields([
@@ -85,7 +92,7 @@ public function build($config)
 
 }
 
-class FragmentsTest extends \PHPUnit_Framework_TestCase
+class FragmentsTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
@@ -103,33 +110,31 @@ public function testVariables($query, $expected, $variables)
                 'fields' => [
                     'user' => [
                         'type'    => new UserType(),
-                        'resolve' => function ($args) {
-                            return [
-                                'id'           => 'user-id-1',
-                                'fullName'     => 'Alex',
-                                'reservations' => [
-                                    [
-                                        'id'   => 'cl-1',
-                                        'user' => [
-                                            'id'       => 'user-id-2',
-                                            'fullName' => 'User class1'
-                                        ],
+                        'resolve' => fn($args) => [
+                            'id'           => 'user-id-1',
+                            'fullName'     => 'Alex',
+                            'reservations' => [
+                                [
+                                    'id'   => 'cl-1',
+                                    'user' => [
+                                        'id'       => 'user-id-2',
+                                        'fullName' => 'User class1'
                                     ],
-                                    [
-                                        'id'      => 'court-1',
-                                        'players' => [
-                                            [
-                                                'id'   => 'player-id-1',
-                                                'user' => [
-                                                    'id'       => 'user-id-3',
-                                                    'fullName' => 'User court1'
-                                                ]
+                                ],
+                                [
+                                    'id'      => 'court-1',
+                                    'players' => [
+                                        [
+                                            'id'   => 'player-id-1',
+                                            'user' => [
+                                                'id'       => 'user-id-3',
+                                                'fullName' => 'User court1'
                                             ]
                                         ]
-                                    ],
-                                ]
-                            ];
-                        },
+                                    ]
+                                ],
+                            ]
+                        ],
                     ],
                 ]
             ])
@@ -217,12 +222,10 @@ public function testSimpleFragment()
                 'fields' => [
                     'user' => [
                         'type'    => new UserType(),
-                        'resolve' => function ($args) {
-                            return [
-                                'id'       => 'user-id-1',
-                                'fullName' => 'Alex',
-                            ];
-                        },
+                        'resolve' => fn($args) => [
+                            'id'       => 'user-id-1',
+                            'fullName' => 'Alex',
+                        ],
                         'args' => [
                             'id' => new IntType(),
                         ]
diff --git a/tests/Schema/InputObjectDefaultValuesTest.php b/tests/Schema/InputObjectDefaultValuesTest.php
index a13c60d3..274158ce 100644
--- a/tests/Schema/InputObjectDefaultValuesTest.php
+++ b/tests/Schema/InputObjectDefaultValuesTest.php
@@ -13,7 +13,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class InputObjectDefaultValuesTest extends \PHPUnit_Framework_TestCase
+class InputObjectDefaultValuesTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testDefaultEnum()
@@ -49,11 +49,9 @@ public function testDefaultEnum()
                                 ]
                             ])
                         ],
-                        'resolve'    => function ($source, $args) {
-                            return sprintf('Result with level %s and status %s',
-                                $args['statObject']['level'], $args['statObject']['status']
-                            );
-                        },
+                        'resolve'    => fn($source, $args) => sprintf('Result with level %s and status %s',
+                            $args['statObject']['level'], $args['statObject']['status']
+                        ),
                     ],
                     'enumObject' => [
                         'type' => new ObjectType([
@@ -62,11 +60,9 @@ public function testDefaultEnum()
                                 'status' => $enumType
                             ]
                         ]),
-                        'resolve' => function() {
-                            return [
-                                'status' => null
-                            ];
-                        }
+                        'resolve' => fn() => [
+                            'status' => null
+                        ]
                     ],
 
                 ]
diff --git a/tests/Schema/InputParseTest.php b/tests/Schema/InputParseTest.php
index d3bc3b86..473ee0a2 100644
--- a/tests/Schema/InputParseTest.php
+++ b/tests/Schema/InputParseTest.php
@@ -9,7 +9,7 @@
 use Youshido\GraphQL\Type\Scalar\DateTimeTzType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class InputParseTest extends \PHPUnit_Framework_TestCase
+class InputParseTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
@@ -30,12 +30,10 @@ public function testDateInput($query, $expected)
                             'from'   => new DateTimeType('Y-m-d H:i:s'),
                             'fromtz' => new DateTimeTzType(),
                         ],
-                        'resolve' => function ($source, $args) {
-                            return sprintf('Result with %s date and %s tz',
-                                empty($args['from']) ? 'default' : $args['from']->format('Y-m-d H:i:s'),
-                                empty($args['fromtz']) ? 'default' : $args['fromtz']->format('r')
-                            );
-                        },
+                        'resolve' => fn($source, $args) => sprintf('Result with %s date and %s tz',
+                            empty($args['from']) ? 'default' : $args['from']->format('Y-m-d H:i:s'),
+                            empty($args['fromtz']) ? 'default' : $args['fromtz']->format('r')
+                        ),
                     ],
                 ]
             ])
diff --git a/tests/Schema/IntrospectionTest.php b/tests/Schema/IntrospectionTest.php
index 7bdafee0..29913885 100644
--- a/tests/Schema/IntrospectionTest.php
+++ b/tests/Schema/IntrospectionTest.php
@@ -25,7 +25,7 @@
 use Youshido\Tests\DataProvider\TestEmptySchema;
 use Youshido\Tests\DataProvider\TestSchema;
 
-class IntrospectionTest extends \PHPUnit_Framework_TestCase
+class IntrospectionTest extends \PHPUnit\Framework\TestCase
 {
     private $introspectionQuery = <<<TEXT
 query IntrospectionQuery {
@@ -139,12 +139,10 @@ public function testPredefinedQueries($query, $expectedResponse)
             'description'       => 'latest description',
             'deprecationReason' => 'for test',
             'isDeprecated'      => true,
-            'resolve'           => function () {
-                return [
-                    'id'   => 1,
-                    'name' => 'Alex'
-                ];
-            }
+            'resolve'           => fn() => [
+                'id'   => 1,
+                'name' => 'Alex'
+            ]
         ]));
 
         $processor = new Processor($schema);
@@ -295,7 +293,7 @@ public function testCombinedFields()
                 'id'   => ['type' => new IntType()],
                 'name' => ['type' => new IntType()],
             ],
-            'resolveType' => function ($type) {
+            'resolveType' => function ($type): void {
 
             }
         ]);
@@ -323,7 +321,7 @@ public function testCombinedFields()
         $unionType = new UnionType([
             'name'        => 'UnionType',
             'types'       => [$object1, $object2],
-            'resolveType' => function () {
+            'resolveType' => function (): void {
 
             }
         ]);
@@ -334,12 +332,10 @@ public function testCombinedFields()
             'args'    => [
                 'id' => ['type' => TypeMap::TYPE_INT]
             ],
-            'resolve' => function () {
-                return [
-                    'id'   => 1,
-                    'name' => 'Alex'
-                ];
-            }
+            'resolve' => fn() => [
+                'id'   => 1,
+                'name' => 'Alex'
+            ]
         ]));
 
         $schema->addMutationField(new Field([
@@ -360,9 +356,7 @@ public function testCombinedFields()
                     ]
                 ])
             ],
-            'resolve' => function () {
-                return null;
-            }
+            'resolve' => fn() => null
         ]));
 
         $processor = new Processor($schema);
diff --git a/tests/Schema/NonNullableTest.php b/tests/Schema/NonNullableTest.php
index 8069cc35..15aff390 100644
--- a/tests/Schema/NonNullableTest.php
+++ b/tests/Schema/NonNullableTest.php
@@ -16,22 +16,20 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class uid
+class uid implements \Stringable
 {
-    private $uid;
-
-    public function __construct($uid)
+    public function __construct(private $uid)
     {
-        $this->uid = $uid;
     }
 
-    public function __toString()
+    #[\Override]
+    public function __toString(): string
     {
-        return $this->uid;
+        return (string) $this->uid;
     }
 }
 
-class NonNullableTest extends \PHPUnit_Framework_TestCase
+class NonNullableTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
@@ -48,15 +46,11 @@ public function testNullableResolving($query, $expected)
                 'fields' => [
                     'nonNullScalar'        => [
                         'type'    => new NonNullType(new IntType()),
-                        'resolve' => function () {
-                            return null;
-                        },
+                        'resolve' => fn() => null,
                     ],
                     'nonNullList'          => [
                         'type'    => new NonNullType(new ListType(new IntType())),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ],
                     'user'                 => [
                         'type'    => new NonNullType(new ObjectType([
@@ -66,36 +60,28 @@ public function testNullableResolving($query, $expected)
                                 'name' => new StringType(),
                             ]
                         ])),
-                        'resolve' => function () {
-                            return [
-                                'id'   => new uid('6cfb044c-9c0a-4ddd-9ef8-a0b940818db3'),
-                                'name' => 'Alex'
-                            ];
-                        }
+                        'resolve' => fn() => [
+                            'id'   => new uid('6cfb044c-9c0a-4ddd-9ef8-a0b940818db3'),
+                            'name' => 'Alex'
+                        ]
                     ],
                     'nonNullListOfNpnNull' => [
                         'type'    => new NonNullType(new ListType(new NonNullType(new IntType()))),
-                        'resolve' => function () {
-                            return [1, null];
-                        }
+                        'resolve' => fn() => [1, null]
                     ],
                     'nonNullArgument'     => [
                         'args'    => [
                             'ids' => new NonNullType(new ListType(new IntType()))
                         ],
                         'type'    => new IntType(),
-                        'resolve' => function () {
-                            return 1;
-                        }
+                        'resolve' => fn() => 1
                     ],
                     'nonNullArgument2'     => [
                         'args'    => [
                             'ids' => new NonNullType(new ListType(new NonNullType(new IntType())))
                         ],
                         'type'    => new IntType(),
-                        'resolve' => function () {
-                            return 1;
-                        }
+                        'resolve' => fn() => 1
                     ],
                 ]
             ])
diff --git a/tests/Schema/ProcessorTest.php b/tests/Schema/ProcessorTest.php
index 545416c7..6c6051e6 100644
--- a/tests/Schema/ProcessorTest.php
+++ b/tests/Schema/ProcessorTest.php
@@ -31,7 +31,7 @@
 use Youshido\Tests\DataProvider\TestObjectType;
 use Youshido\Tests\DataProvider\TestSchema;
 
-class ProcessorTest extends \PHPUnit_Framework_TestCase
+class ProcessorTest extends \PHPUnit\Framework\TestCase
 {
 
     private $_counter = 0;
@@ -110,9 +110,7 @@ public function testListNullResponse()
                 'fields' => [
                     'list' => [
                         'type'    => new ListType(new StringType()),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ]
                 ]
             ])
@@ -130,9 +128,7 @@ public function testSubscriptionNullResponse()
                 'fields' => [
                     'list' => [
                         'type'    => new ListType(new StringType()),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ]
                 ]
             ])
@@ -156,15 +152,11 @@ public function testSchemaOperations()
                                     'args'    => [
                                         'shorten' => new BooleanType()
                                     ],
-                                    'resolve' => function ($value, $args) {
-                                        return empty($args['shorten']) ? $value['firstName'] : $value['firstName'];
-                                    }
+                                    'resolve' => fn($value, $args) => empty($args['shorten']) ? $value['firstName'] : $value['firstName']
                                 ],
                                 'id_alias'  => [
                                     'type'    => new IdType(),
-                                    'resolve' => function ($value) {
-                                        return $value['id'];
-                                    }
+                                    'resolve' => fn($value) => $value['id']
                                 ],
                                 'lastName'  => new StringType(),
                                 'code'      => new StringType(),
@@ -189,21 +181,15 @@ public function testSchemaOperations()
                     ],
                     'randomUser'        => [
                         'type'    => new TestObjectType(),
-                        'resolve' => function () {
-                            return ['invalidField' => 'John'];
-                        }
+                        'resolve' => fn() => ['invalidField' => 'John']
                     ],
                     'invalidValueQuery' => [
                         'type'    => new TestObjectType(),
-                        'resolve' => function () {
-                            return 'stringValue';
-                        }
+                        'resolve' => fn() => 'stringValue'
                     ],
                     'labels'            => [
                         'type'    => new ListType(new StringType()),
-                        'resolve' => function () {
-                            return ['one', 'two'];
-                        }
+                        'resolve' => fn() => ['one', 'two']
                     ]
                 ],
             ])
@@ -238,9 +224,7 @@ public function testSchemaOperations()
             ->addField(new Field([
                 'name'    => 'increaseCounter',
                 'type'    => new IntType(),
-                'resolve' => function ($value, $args, ResolveInfo $info) {
-                    return $this->_counter += $args['amount'];
-                },
+                'resolve' => fn($value, $args, ResolveInfo $info) => $this->_counter += $args['amount'],
                 'args'    => [
                     'amount' => [
                         'type'    => new IntType(),
@@ -250,15 +234,11 @@ public function testSchemaOperations()
             ]))->addField(new Field([
                 'name'    => 'invalidResolveTypeMutation',
                 'type'    => new NonNullType(new IntType()),
-                'resolve' => function () {
-                    return null;
-                }
+                'resolve' => fn() => null
             ]))->addField(new Field([
                 'name'    => 'interfacedMutation',
                 'type'    => new TestInterfaceType(),
-                'resolve' => function () {
-                    return ['name' => 'John'];
-                }
+                'resolve' => fn() => ['name' => 'John']
             ]));
         $processor->processPayload('mutation { increaseCounter }');
         $this->assertEquals(['data' => ['increaseCounter' => 1]], $processor->getResponseData());
@@ -385,9 +365,7 @@ public function testEnumType()
                             ]))
                         ],
                         'type'    => new StringType(),
-                        'resolve' => function ($value, $args) {
-                            return $args['argument1'];
-                        }
+                        'resolve' => fn($value, $args) => $args['argument1']
                     ]
                 ]
             ])
@@ -438,45 +416,31 @@ public function testListEnumsSchemaOperations()
                 'fields' => [
                     'listQuery'                 => [
                         'type'    => new ListType(new TestEnumType()),
-                        'resolve' => function () {
-                            return 'invalid list';
-                        }
+                        'resolve' => fn() => 'invalid list'
                     ],
                     'listEnumQuery'             => [
                         'type'    => new ListType(new TestEnumType()),
-                        'resolve' => function () {
-                            return ['invalid enum'];
-                        }
+                        'resolve' => fn() => ['invalid enum']
                     ],
                     'invalidEnumQuery'          => [
                         'type'    => new TestEnumType(),
-                        'resolve' => function () {
-                            return 'invalid enum';
-                        }
+                        'resolve' => fn() => 'invalid enum'
                     ],
                     'enumQuery'                 => [
                         'type'    => new TestEnumType(),
-                        'resolve' => function () {
-                            return 1;
-                        }
+                        'resolve' => fn() => 1
                     ],
                     'invalidNonNullQuery'       => [
                         'type'    => new NonNullType(new IntType()),
-                        'resolve' => function () {
-                            return null;
-                        }
+                        'resolve' => fn() => null
                     ],
                     'invalidNonNullInsideQuery' => [
                         'type'    => new NonNullType(new IntType()),
-                        'resolve' => function () {
-                            return 'hello';
-                        }
+                        'resolve' => fn() => 'hello'
                     ],
                     'objectQuery'               => [
                         'type'    => new TestObjectType(),
-                        'resolve' => function () {
-                            return ['name' => 'John'];
-                        }
+                        'resolve' => fn() => ['name' => 'John']
                     ],
                     'deepObjectQuery'           => [
                         'type'    => new ObjectType([
@@ -486,14 +450,12 @@ public function testListEnumsSchemaOperations()
                                 'enum'   => new TestEnumType(),
                             ],
                         ]),
-                        'resolve' => function () {
-                            return [
-                                'object' => [
-                                    'name' => 'John'
-                                ],
-                                'enum'   => 1
-                            ];
-                        },
+                        'resolve' => fn() => [
+                            'object' => [
+                                'name' => 'John'
+                            ],
+                            'enum'   => 1
+                        ],
                     ],
                 ]
             ])
@@ -579,9 +541,7 @@ public function testTypedFragment()
         $invalidUnion = new UnionType([
             'name'        => 'TestUnion',
             'types'       => [$object1, $object2],
-            'resolveType' => function ($object) use ($object3) {
-                return $object3;
-            }
+            'resolveType' => fn($object) => $object3
         ]);
         $processor    = new Processor(new Schema([
             'query' => new ObjectType([
@@ -607,9 +567,7 @@ public function testTypedFragment()
                     ],
                     'invalidUnion' => [
                         'type'    => $invalidUnion,
-                        'resolve' => function () {
-                            return ['name' => 'name resolved'];
-                        }
+                        'resolve' => fn() => ['name' => 'name resolved']
                     ],
                 ]
             ])
@@ -677,9 +635,7 @@ public function testContainer()
                 'fields' => [
                     'currentUser' => [
                         'type'    => new StringType(),
-                        'resolve' => function ($source, $args, ResolveInfo $info) {
-                            return $info->getContainer()->get('user')['name'];
-                        }
+                        'resolve' => fn($source, $args, ResolveInfo $info) => $info->getContainer()->get('user')['name']
                     ]
                 ]
             ])
@@ -710,24 +666,20 @@ public function testComplexityReducer()
                                                 'args'    => [
                                                     'shorten' => new BooleanType()
                                                 ],
-                                                'resolve' => function ($value, $args) {
-                                                    return empty($args['shorten']) ? $value['firstName'] : $value['firstName'];
-                                                }
+                                                'resolve' => fn($value, $args) => empty($args['shorten']) ? $value['firstName'] : $value['firstName']
                                             ],
                                             'lastName'  => new StringType(),
                                             'code'      => new StringType(),
                                             'likes'     => [
                                                 'type'    => new IntType(),
                                                 'cost'    => 10,
-                                                'resolve' => function () {
-                                                    return 42;
-                                                }
+                                                'resolve' => fn() => 42
                                             ]
                                         ]
                                     ]
                                 ),
                                 'cost'    => function ($args, $context, $childCost) {
-                                    $argsCost = isset($args['cost']) ? $args['cost'] : 1;
+                                    $argsCost = $args['cost'] ?? 1;
 
                                     return 1 + $argsCost * $childCost;
                                 },
@@ -774,7 +726,19 @@ public function testComplexityReducer()
 
         // don't let complexity reducer affect query errors
         $processor->processPayload('{ me { badfield } }');
-        $this->assertArraySubset(['errors' => [['message' => 'Field "badfield" not found in type "User". Available fields are: "firstName", "lastName", "code", "likes"']]], $processor->getResponseData());
+
+        foreach ([
+            'errors' => [
+                [
+                    'message' => 'Field "badfield" not found in type "User". Available fields are: "firstName", "lastName", "code", "likes"',
+                    'locations' => [['line'=>1, 'column'=>8]]
+                ]
+            ]
+        ] as $key => $value) {
+            $this->assertArrayHasKey($key, $processor->getResponseData());
+            $this->assertSame($value, $processor->getResponseData()[$key]);
+        }
+
         $processor->getExecutionContext()->clearErrors();
 
         foreach (range(1, 5) as $cost_multiplier) {
diff --git a/tests/Schema/ResolveInfoTest.php b/tests/Schema/ResolveInfoTest.php
index af903980..26651edb 100644
--- a/tests/Schema/ResolveInfoTest.php
+++ b/tests/Schema/ResolveInfoTest.php
@@ -17,7 +17,7 @@
 use Youshido\GraphQL\Type\Scalar\IntType;
 use Youshido\Tests\DataProvider\TestSchema;
 
-class ResolveInfoTest extends \PHPUnit_Framework_TestCase
+class ResolveInfoTest extends \PHPUnit\Framework\TestCase
 {
     public function testMethods()
     {
diff --git a/tests/Schema/SchemaTest.php b/tests/Schema/SchemaTest.php
index 5c1c75fe..953fe020 100644
--- a/tests/Schema/SchemaTest.php
+++ b/tests/Schema/SchemaTest.php
@@ -19,7 +19,7 @@
 use Youshido\Tests\DataProvider\TestObjectType;
 use Youshido\Tests\DataProvider\TestSchema;
 
-class SchemaTest extends \PHPUnit_Framework_TestCase
+class SchemaTest extends \PHPUnit\Framework\TestCase
 {
 
     public function testStandaloneEmptySchema()
@@ -36,7 +36,7 @@ public function testStandaloneSchema()
 
         $this->assertEquals(1, count($schema->getMutationType()->getFields()));
 
-        $schema->addMutationField('changeUser', ['type' => new TestObjectType(), 'resolve' => function () {
+        $schema->addMutationField('changeUser', ['type' => new TestObjectType(), 'resolve' => function (): void {
         }]);
         $this->assertEquals(2, count($schema->getMutationType()->getFields()));
 
@@ -68,9 +68,7 @@ public function testCustomTypes()
             'fields'      => [
                 'name' => new StringType(),
             ],
-            'resolveType' => function () use ($authorType) {
-                return $authorType;
-            }
+            'resolveType' => fn() => $authorType
         ]);
 
         $authorType = new ObjectType([
@@ -87,11 +85,9 @@ public function testCustomTypes()
                 'fields' => [
                     'user' => [
                         'type'    => $userInterface,
-                        'resolve' => function () {
-                            return [
-                                'name' => 'Alex'
-                            ];
-                        }
+                        'resolve' => fn() => [
+                            'name' => 'Alex'
+                        ]
                     ]
                 ]
             ])
@@ -109,7 +105,11 @@ public function testCustomTypes()
                     }
                 }');
         $data = $processor->getResponseData();
-        $this->assertArraySubset([11 => ['name' => 'Author']], $data['data']['__schema']['types']);
+
+        foreach ([11 => ['name' => 'Author']] as $key => $value) {
+            $this->assertArrayHasKey($key, $data['data']['__schema']['types']);
+            $this->assertSame($value, $data['data']['__schema']['types'][$key]);
+        }
 
         $processor->processPayload('{ user { name { } } }');
         $result = $processor->getResponseData();
diff --git a/tests/Schema/VariablesTest.php b/tests/Schema/VariablesTest.php
index c04ab334..7619f158 100644
--- a/tests/Schema/VariablesTest.php
+++ b/tests/Schema/VariablesTest.php
@@ -10,7 +10,7 @@
 use Youshido\GraphQL\Type\Scalar\IdType;
 use Youshido\GraphQL\Type\Scalar\StringType;
 
-class VariablesTest extends \PHPUnit_Framework_TestCase
+class VariablesTest extends \PHPUnit\Framework\TestCase
 {
     public function testInvalidNullableList()
     {
@@ -23,9 +23,7 @@ public function testInvalidNullableList()
                         'args'    => [
                             'ids' => new ListType(new NonNullType(new IdType())),
                         ],
-                        'resolve' => function () {
-                            return 'item';
-                        },
+                        'resolve' => fn() => 'item',
                     ],
                 ],
             ]),
@@ -100,9 +98,7 @@ public function testVariables($query, $expected, $variables)
                         'args'    => [
                             'sortOrder' => new StringType(),
                         ],
-                        'resolve' => function ($args) {
-                            return sprintf('Result with %s order', empty($args['sortOrder']) ? 'default' : $args['sortOrder']);
-                        },
+                        'resolve' => fn($args) => sprintf('Result with %s order', empty($args['sortOrder']) ? 'default' : $args['sortOrder']),
                     ],
                 ],
             ]),
diff --git a/tests/StarWars/Schema/CharacterInterface.php b/tests/StarWars/Schema/CharacterInterface.php
index 273aaf14..63826b20 100644
--- a/tests/StarWars/Schema/CharacterInterface.php
+++ b/tests/StarWars/Schema/CharacterInterface.php
@@ -16,6 +16,7 @@
 
 class CharacterInterface extends AbstractInterfaceType
 {
+    #[\Override]
     public function build($config)
     {
         $config
@@ -23,29 +24,30 @@ public function build($config)
             ->addField('name', new NonNullType(new StringType()))
             ->addField('friends', [
                 'type'    => new ListType(new CharacterInterface()),
-                'resolve' => function ($value) {
-                    return $value['friends'];
-                }
+                'resolve' => fn($value) => $value['friends']
             ])
             ->addField('appearsIn', new ListType(new EpisodeEnum()));
     }
 
+    #[\Override]
     public function getDescription()
     {
         return 'A character in the Star Wars Trilogy';
     }
 
+    #[\Override]
     public function getName()
     {
         return 'Character';
     }
 
+    #[\Override]
     public function resolveType($object)
     {
         $humans = StarWarsData::humans();
         $droids = StarWarsData::droids();
 
-        $id = isset($object['id']) ? $object['id'] : $object;
+        $id = $object['id'] ?? $object;
 
         if (isset($humans[$id])) {
             return new HumanType();
diff --git a/tests/StarWars/Schema/DroidType.php b/tests/StarWars/Schema/DroidType.php
index 7b4101df..e2dadf59 100644
--- a/tests/StarWars/Schema/DroidType.php
+++ b/tests/StarWars/Schema/DroidType.php
@@ -16,23 +16,24 @@ class DroidType extends HumanType
     /**
      * @return String type name
      */
+    #[\Override]
     public function getName()
     {
         return 'Droid';
     }
 
+    #[\Override]
     public function build($config)
     {
         parent::build($config);
 
-        $config->getField('friends')->getConfig()->set('resolve', function ($droid) {
-            return StarWarsData::getFriends($droid);
-        });
+        $config->getField('friends')->getConfig()->set('resolve', fn($droid) => StarWarsData::getFriends($droid));
 
         $config
             ->addField('primaryFunction', TypeMap::TYPE_STRING);
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new CharacterInterface()];
diff --git a/tests/StarWars/Schema/EpisodeEnum.php b/tests/StarWars/Schema/EpisodeEnum.php
index 2c4c4436..fcdf28eb 100644
--- a/tests/StarWars/Schema/EpisodeEnum.php
+++ b/tests/StarWars/Schema/EpisodeEnum.php
@@ -13,6 +13,7 @@
 class EpisodeEnum extends AbstractEnumType
 {
 
+    #[\Override]
     public function getValues()
     {
         return [
@@ -37,6 +38,7 @@ public function getValues()
     /**
      * @return String type name
      */
+    #[\Override]
     public function getName()
     {
         return 'Episode';
diff --git a/tests/StarWars/Schema/HumanType.php b/tests/StarWars/Schema/HumanType.php
index 8d02d346..e3adea61 100644
--- a/tests/StarWars/Schema/HumanType.php
+++ b/tests/StarWars/Schema/HumanType.php
@@ -18,6 +18,7 @@
 class HumanType extends AbstractObjectType
 {
 
+    #[\Override]
     public function build($config)
     {
         $config
@@ -25,14 +26,13 @@ public function build($config)
             ->addField('name', new NonNullType(new StringType()))
             ->addField('friends', [
                 'type'    => new ListType(new CharacterInterface()),
-                'resolve' => function ($droid) {
-                    return StarWarsData::getFriends($droid);
-                },
+                'resolve' => fn($droid) => StarWarsData::getFriends($droid),
             ])
             ->addField('appearsIn', new ListType(new EpisodeEnum()))
             ->addField('homePlanet', TypeMap::TYPE_STRING);
     }
 
+    #[\Override]
     public function getInterfaces()
     {
         return [new CharacterInterface()];
diff --git a/tests/StarWars/Schema/StarWarsData.php b/tests/StarWars/Schema/StarWarsData.php
index d2d28607..15b01b13 100644
--- a/tests/StarWars/Schema/StarWarsData.php
+++ b/tests/StarWars/Schema/StarWarsData.php
@@ -119,11 +119,8 @@ static function getCharacter($id)
         if (isset($humans[$id])) {
             return $humans[$id];
         }
-        if (isset($droids[$id])) {
-            return $droids[$id];
-        }
 
-        return null;
+        return $droids[$id] ?? null;
     }
 
     /**
@@ -146,6 +143,6 @@ static function getHero($episode)
      */
     static function getFriends($character)
     {
-        return array_map([__CLASS__, 'getCharacter'], $character['friends']);
+        return array_map(self::getCharacter(...), $character['friends']);
     }
 }
diff --git a/tests/StarWars/Schema/StarWarsQueryType.php b/tests/StarWars/Schema/StarWarsQueryType.php
index e54f072d..4f8c5589 100644
--- a/tests/StarWars/Schema/StarWarsQueryType.php
+++ b/tests/StarWars/Schema/StarWarsQueryType.php
@@ -19,11 +19,13 @@ class StarWarsQueryType extends AbstractObjectType
     /**
      * @return String type name
      */
+    #[\Override]
     public function getName()
     {
         return 'Query';
     }
 
+    #[\Override]
     public function build($config)
     {
         $config
@@ -32,9 +34,7 @@ public function build($config)
                 'args'    => [
                     'episode' => ['type' => new EpisodeEnum()]
                 ],
-                'resolve' => function ($root, $args) {
-                    return StarWarsData::getHero(isset($args['episode']) ? $args['episode'] : null);
-                },
+                'resolve' => fn($root, $args) => StarWarsData::getHero($args['episode'] ?? null),
             ])
             ->addField(new Field([
                 'name'    => 'human',
@@ -45,7 +45,7 @@ public function build($config)
                 'resolve' => function ($value = null, $args = []) {
                     $humans = StarWarsData::humans();
 
-                    return isset($humans[$args['id']]) ? $humans[$args['id']] : null;
+                    return $humans[$args['id']] ?? null;
                 }
             ]))
             ->addField(new Field([
@@ -57,7 +57,7 @@ public function build($config)
                 'resolve' => function ($value = null, $args = []) {
                     $droids = StarWarsData::droids();
 
-                    return isset($droids[$args['id']]) ? $droids[$args['id']] : null;
+                    return $droids[$args['id']] ?? null;
                 }
             ]));
     }
diff --git a/tests/StarWars/Schema/StarWarsSchema.php b/tests/StarWars/Schema/StarWarsSchema.php
index 1ed58262..b1a59b46 100644
--- a/tests/StarWars/Schema/StarWarsSchema.php
+++ b/tests/StarWars/Schema/StarWarsSchema.php
@@ -14,6 +14,7 @@
 class StarWarsSchema extends AbstractSchema
 {
 
+    #[\Override]
     public function build(SchemaConfig $config)
     {
         $config->setQuery(new StarWarsQueryType());
diff --git a/tests/StarWars/StarWarsTest.php b/tests/StarWars/StarWarsTest.php
index 7f69a4b2..a6a63b33 100644
--- a/tests/StarWars/StarWarsTest.php
+++ b/tests/StarWars/StarWarsTest.php
@@ -11,7 +11,7 @@
 use Youshido\GraphQL\Execution\Processor;
 use Youshido\Tests\StarWars\Schema\StarWarsSchema;
 
-class StarWarsTest extends \PHPUnit_Framework_TestCase
+class StarWarsTest extends \PHPUnit\Framework\TestCase
 {
 
     /**