diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index 6e540218..9968c69c 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -25,7 +25,7 @@ parameters:
 			path: src/Reflection/EnumReflectionProperty.php
 
 		-
-			message: '#^PHPDoc tag @var with type Doctrine\\Persistence\\Mapping\\ClassMetadata\<object\> is not subtype of native type PHPUnit\\Framework\\MockObject\\MockObject\.$#'
+			message: '#^PHPDoc tag @var with type Doctrine\\Persistence\\Mapping\\ClassMetadata\<object\> is not subtype of native type PHPUnit\\Framework\\MockObject\\Stub\.$#'
 			identifier: varTag.nativeType
 			count: 1
 			path: tests/Mapping/ClassMetadataFactoryTest.php
diff --git a/src/Mapping/Driver/ClassNames.php b/src/Mapping/Driver/ClassNames.php
index 9014ddd9..7d1b001c 100644
--- a/src/Mapping/Driver/ClassNames.php
+++ b/src/Mapping/Driver/ClassNames.php
@@ -13,7 +13,7 @@
 {
     /** @param list<class-string> $classNames */
     public function __construct(
-        private array $classNames,
+        private readonly array $classNames,
     ) {
     }
 
diff --git a/src/Mapping/Driver/DefaultFileLocator.php b/src/Mapping/Driver/DefaultFileLocator.php
index f8df1f1d..239fbed4 100644
--- a/src/Mapping/Driver/DefaultFileLocator.php
+++ b/src/Mapping/Driver/DefaultFileLocator.php
@@ -47,7 +47,6 @@ public function __construct(
         private string|null $fileExtension = null,
     ) {
         $this->addPaths((array) $paths);
-        $this->fileExtension = $fileExtension;
     }
 
     /**
diff --git a/src/Mapping/Driver/FileClassLocator.php b/src/Mapping/Driver/FileClassLocator.php
index 09d5e534..2fd525d5 100644
--- a/src/Mapping/Driver/FileClassLocator.php
+++ b/src/Mapping/Driver/FileClassLocator.php
@@ -39,7 +39,7 @@
 {
     /** @param iterable<SplFileInfo> $files An iterable of files to include. */
     public function __construct(
-        private iterable $files,
+        private readonly iterable $files,
     ) {
     }
 
diff --git a/src/Mapping/Driver/MappingDriverChain.php b/src/Mapping/Driver/MappingDriverChain.php
index ed773443..b76a3571 100644
--- a/src/Mapping/Driver/MappingDriverChain.php
+++ b/src/Mapping/Driver/MappingDriverChain.php
@@ -10,7 +10,7 @@
 
 use function array_keys;
 use function spl_object_id;
-use function strpos;
+use function str_starts_with;
 
 /**
  * The DriverChain allows you to add multiple other mapping drivers for
@@ -58,7 +58,7 @@ public function getDrivers(): array
     public function loadMetadataForClass(string $className, ClassMetadata $metadata): void
     {
         foreach ($this->drivers as $namespace => $driver) {
-            if (strpos($className, $namespace) === 0) {
+            if (str_starts_with($className, $namespace)) {
                 $driver->loadMetadataForClass($className, $metadata);
 
                 return;
@@ -91,7 +91,7 @@ public function getAllClassNames(): array
             }
 
             foreach ($driverClasses[$oid] as $className) {
-                if (strpos($className, $namespace) !== 0) {
+                if (! str_starts_with($className, $namespace)) {
                     continue;
                 }
 
@@ -112,7 +112,7 @@ public function getAllClassNames(): array
     public function isTransient(string $className): bool
     {
         foreach ($this->drivers as $namespace => $driver) {
-            if (strpos($className, $namespace) === 0) {
+            if (str_starts_with($className, $namespace)) {
                 return $driver->isTransient($className);
             }
         }
diff --git a/src/Mapping/Driver/SymfonyFileLocator.php b/src/Mapping/Driver/SymfonyFileLocator.php
index 21473394..b7594ae6 100644
--- a/src/Mapping/Driver/SymfonyFileLocator.php
+++ b/src/Mapping/Driver/SymfonyFileLocator.php
@@ -48,9 +48,6 @@ final class SymfonyFileLocator implements FileLocator
      */
     protected array $prefixes = [];
 
-    /** File extension that is searched for. */
-    protected string|null $fileExtension;
-
     /**
      * Represents PHP namespace delimiters when looking for files
      */
@@ -63,11 +60,11 @@ final class SymfonyFileLocator implements FileLocator
      */
     public function __construct(
         array $prefixes,
-        string $fileExtension = '',
+        /** File extension that is searched for. */
+        protected string|null $fileExtension = '',
         string $nsSeparator = '.',
     ) {
         $this->addNamespacePrefixes($prefixes);
-        $this->fileExtension = $fileExtension;
 
         if ($nsSeparator === '') {
             throw new InvalidArgumentException('Namespace separator should not be empty');
diff --git a/tests/Event/PreUpdateEventArgsTest.php b/tests/Event/PreUpdateEventArgsTest.php
index fef09458..508af502 100644
--- a/tests/Event/PreUpdateEventArgsTest.php
+++ b/tests/Event/PreUpdateEventArgsTest.php
@@ -70,7 +70,7 @@ private function createTestPreUpdateEventArgs(): PreUpdateEventArgs
     {
         $entity = new TestObject();
 
-        $objectManager = $this->createMock(ObjectManager::class);
+        $objectManager = self::createStub(ObjectManager::class);
 
         $entityChangeset = [
             'name' => ['old', 'new'],
diff --git a/tests/ManagerRegistryTest.php b/tests/ManagerRegistryTest.php
index 7f0d17ec..37ee415b 100644
--- a/tests/ManagerRegistryTest.php
+++ b/tests/ManagerRegistryTest.php
@@ -129,7 +129,7 @@ public function testResetManager(): void
 
     public function testGetRepository(): void
     {
-        $repository = $this->createMock(ObjectRepository::class);
+        $repository = self::createStub(ObjectRepository::class);
 
         $defaultManager = $this->mr->getManager();
         assert($defaultManager instanceof MockObject);
@@ -154,7 +154,7 @@ public function testGetRepositoryWithSpecificManagerName(): void
             $this->getManagerFactory(),
         );
 
-        $repository = $this->createMock(ObjectRepository::class);
+        $repository = self::createStub(ObjectRepository::class);
 
         $defaultManager = $this->mr->getManager();
         assert($defaultManager instanceof MockObject);
@@ -185,7 +185,7 @@ public function testGetRepositoryWithManagerDetection(): void
             $this->getManagerFactory(),
         );
 
-        $repository = $this->createMock(ObjectRepository::class);
+        $repository = self::createStub(ObjectRepository::class);
 
         $defaultManager = $this->mr->getManager();
         assert($defaultManager instanceof MockObject);
@@ -208,9 +208,10 @@ private function getManagerFactory(): Closure
     {
         return function (string $name) {
             $mock = $this->createMock(ObjectManager::class);
+            $mock->expects($this->never())->method('clear');
 
-            $driver   = $this->createMock(MappingDriver::class);
-            $metadata = $this->createMock(ClassMetadata::class);
+            $driver   = self::createStub(MappingDriver::class);
+            $metadata = self::createStub(ClassMetadata::class);
 
             $metadata
                 ->method('getName')
diff --git a/tests/Mapping/AbstractClassMetadataFactoryTest.php b/tests/Mapping/AbstractClassMetadataFactoryTest.php
index 45647138..c9b148e4 100644
--- a/tests/Mapping/AbstractClassMetadataFactoryTest.php
+++ b/tests/Mapping/AbstractClassMetadataFactoryTest.php
@@ -29,7 +29,7 @@ public function testItSkipsTransientClasses(): void
         $cmf    = $this->createTestFactory($driver);
 
         $metadataCallCount                     = 0;
-        $cmf->newClassMetadataInstanceCallback = function ($className) use (&$metadataCallCount) {
+        $cmf->newClassMetadataInstanceCallback = static function ($className) use (&$metadataCallCount) {
             $metadataCallCount++;
             if ($metadataCallCount === 1) {
                 self::assertEquals(SomeGrandParentEntity::class, $className);
@@ -37,7 +37,7 @@ public function testItSkipsTransientClasses(): void
                 self::assertEquals(SomeEntity::class, $className);
             }
 
-            return $this->createMock(ClassMetadata::class);
+            return self::createStub(ClassMetadata::class);
         };
 
         $driverCallCount = 0;
@@ -71,7 +71,7 @@ public function testItThrowsWhenAttemptingToGetMetadataForAnonymousClass(): void
 
     public function testAnonymousClassIsNotMistakenForShortAlias(): void
     {
-        $driver = $this->createMock(MappingDriver::class);
+        $driver = self::createStub(MappingDriver::class);
         $driver->method('isTransient')->willReturn(false);
         $cmf = $this->createTestFactory($driver);
 
@@ -97,7 +97,7 @@ public function testItThrowsWhenAttemptingToCheckTransientForShortAlias(): void
 
     public function testItGetsTheSameMetadataForBackslashedClassName(): void
     {
-        $driver = $this->createMock(MappingDriver::class);
+        $driver = self::createStub(MappingDriver::class);
         $cmf    = $this->createTestFactory($driver);
 
         $metadata                              = self::createStub(ClassMetadata::class);
@@ -135,8 +135,8 @@ class TestAbstractClassMetadataFactory extends AbstractClassMetadataFactory
 
     /** @param ClassMetadata<object>|null $defaultMetadata */
     public function __construct(
-        private MappingDriver|null $driver = null,
-        private ClassMetadata|null $defaultMetadata = null,
+        private readonly MappingDriver|null $driver = null,
+        private readonly ClassMetadata|null $defaultMetadata = null,
     ) {
     }
 
diff --git a/tests/Mapping/ClassMetadataFactoryTest.php b/tests/Mapping/ClassMetadataFactoryTest.php
index d8a6346a..c6608501 100644
--- a/tests/Mapping/ClassMetadataFactoryTest.php
+++ b/tests/Mapping/ClassMetadataFactoryTest.php
@@ -28,10 +28,10 @@ class ClassMetadataFactoryTest extends TestCase
     #[Override]
     protected function setUp(): void
     {
-        $driver = $this->createMock(MappingDriver::class);
+        $driver = self::createStub(MappingDriver::class);
 
         /** @phpstan-var ClassMetadata<object> */
-        $metadata  = $this->createMock(ClassMetadata::class);
+        $metadata  = self::createStub(ClassMetadata::class);
         $this->cmf = new TestClassMetadataFactory($driver, $metadata);
     }
 
@@ -67,7 +67,7 @@ public function testGetParentMetadata(): void
 
     public function testGetCachedMetadata(): void
     {
-        $metadata = $this->createMock(ClassMetadata::class);
+        $metadata = self::createStub(ClassMetadata::class);
         $cache    = new ArrayAdapter();
         $item     = $cache->getItem($this->cmf->getCacheKey(ChildEntity::class));
         $item->set($metadata);
@@ -92,7 +92,7 @@ public function testCacheGetMetadataFor(): void
 
     public function testWillFallbackOnNotLoadedMetadata(): void
     {
-        $classMetadata = $this->createMock(ClassMetadata::class);
+        $classMetadata = self::createStub(ClassMetadata::class);
 
         $this->cmf->fallbackCallback = static fn () => $classMetadata;
 
diff --git a/tests/Mapping/DriverChainTest.php b/tests/Mapping/DriverChainTest.php
index 66ce22f2..141f6cea 100644
--- a/tests/Mapping/DriverChainTest.php
+++ b/tests/Mapping/DriverChainTest.php
@@ -22,7 +22,7 @@ class DriverChainTest extends TestCase
     public function testDelegateToMatchingNamespaceDriver(string $namespace1, string $namespace2): void
     {
         $className     = DriverChainEntity::class;
-        $classMetadata = $this->createMock(ClassMetadata::class);
+        $classMetadata = self::createStub(ClassMetadata::class);
 
         $chain = new MappingDriverChain();
 
@@ -52,7 +52,7 @@ public function testDelegateToMatchingNamespaceDriver(string $namespace1, string
     public function testLoadMetadataShouldThrowMappingExceptionWhenNoDelegatorWasFound(): void
     {
         $className     = DriverChainEntity::class;
-        $classMetadata = $this->createMock(ClassMetadata::class);
+        $classMetadata = self::createStub(ClassMetadata::class);
 
         $chain = new MappingDriverChain();
 
@@ -87,7 +87,7 @@ public function testGatherAllClassNames(): void
     #[Group('DDC-706')]
     public function testIsTransient(): void
     {
-        $driver1 = $this->createMock(MappingDriver::class);
+        $driver1 = self::createStub(MappingDriver::class);
         $chain   = new MappingDriverChain();
         $chain->addDriver($driver1, 'Doctrine\Tests\Models\CMS');
 
diff --git a/tests/Mapping/FileDriverTest.php b/tests/Mapping/FileDriverTest.php
index 6018fd2d..7ea523c5 100644
--- a/tests/Mapping/FileDriverTest.php
+++ b/tests/Mapping/FileDriverTest.php
@@ -13,6 +13,7 @@
 use Doctrine\Tests\Persistence\Mapping\Fixtures\TestClassMetadata;
 use Override;
 use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\MockObject\Stub;
 use PHPUnit\Framework\TestCase;
 use stdClass;
 
@@ -44,7 +45,7 @@ public function testGetElementFromGlobalFile(): void
 
     public function testGetElementFromFile(): void
     {
-        $locator = $this->newLocator();
+        $locator = $this->newLocator(true);
         $locator->expects(self::once())
                 ->method('findMappingFile')
                 ->with(self::equalTo(stdClass::class))
@@ -57,7 +58,7 @@ public function testGetElementFromFile(): void
 
     public function testGetElementUpdatesClassCache(): void
     {
-        $locator = $this->newLocator();
+        $locator = $this->newLocator(true);
 
         // findMappingFile should only be called once
         $locator->expects(self::once())
@@ -119,7 +120,7 @@ public function testGetAllClassNamesBothSources(): void
 
     public function testGetAllClassNamesBothSourcesNoDupes(): void
     {
-        $locator = $this->newLocator();
+        $locator = $this->newLocator(true);
         $locator->expects(self::once())
                 ->method('getAllClassNames')
                 ->with(self::equalTo('global'))
@@ -139,7 +140,7 @@ public function testGetAllClassNamesBothSourcesNoDupes(): void
 
     public function testIsNotTransient(): void
     {
-        $locator = $this->newLocator();
+        $locator = $this->newLocator(true);
         $locator->expects(self::once())
                 ->method('fileExists')
                 ->with(self::equalTo(stdClass::class))
@@ -155,7 +156,7 @@ public function testIsNotTransient(): void
 
     public function testIsTransient(): void
     {
-        $locator = $this->newLocator();
+        $locator = $this->newLocator(true);
         $locator->expects(self::once())
                 ->method('fileExists')
                 ->with(self::equalTo(NotLoadedClass::class))
@@ -173,10 +174,10 @@ public function testNonLocatorFallback(): void
         self::assertFalse($driver->isTransient(stdClass::class));
     }
 
-    /** @return FileLocator&MockObject */
-    private function newLocator(): MockObject
+    /** @return ($mock is true ? (FileLocator&MockObject) : (FileLocator&Stub)) */
+    private function newLocator(bool $mock = false): FileLocator
     {
-        $locator = $this->createMock(FileLocator::class);
+        $locator = $mock ? $this->createMock(FileLocator::class) : self::createStub(FileLocator::class);
         $locator->method('getFileExtension')->willReturn('.yml');
         $locator->method('getPaths')->willReturn([__DIR__ . '/_files']);
 
@@ -188,9 +189,9 @@ private function createTestFileDriver(string|array|FileLocator $locator, string|
     {
         $driver = new TestFileDriver($locator, $fileExtension);
 
-        $driver->stdClass   = $this->createMock(ClassMetadata::class);
-        $driver->stdGlobal  = $this->createMock(ClassMetadata::class);
-        $driver->stdGlobal2 = $this->createMock(ClassMetadata::class);
+        $driver->stdClass   = self::createStub(ClassMetadata::class);
+        $driver->stdGlobal  = self::createStub(ClassMetadata::class);
+        $driver->stdGlobal2 = self::createStub(ClassMetadata::class);
 
         return $driver;
     }
diff --git a/tests/Mapping/RuntimeReflectionServiceTest.php b/tests/Mapping/RuntimeReflectionServiceTest.php
index e9f18235..4d439e1d 100644
--- a/tests/Mapping/RuntimeReflectionServiceTest.php
+++ b/tests/Mapping/RuntimeReflectionServiceTest.php
@@ -22,9 +22,11 @@ class RuntimeReflectionServiceTest extends TestCase
 
     public mixed $unusedPublicProperty;
 
-    private string $typedNoDefaultProperty;
+    /** @phpstan-ignore property.uninitializedReadonly */
+    private readonly string $typedNoDefaultProperty;
     private string $typedDefaultProperty = '';
-    private string $nonTypedNoDefaultProperty; // phpcs:ignore SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedProperty
+    /** @phpstan-ignore property.uninitializedReadonly */
+    private readonly string $nonTypedNoDefaultProperty; // phpcs:ignore SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedProperty
     private string $nonTypedDefaultProperty = ''; // phpcs:ignore SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedProperty
 
     public string $typedNoDefaultPublicProperty;
diff --git a/tests/ObjectManagerDecoratorTest.php b/tests/ObjectManagerDecoratorTest.php
index 4f15d53c..8b2c170d 100644
--- a/tests/ObjectManagerDecoratorTest.php
+++ b/tests/ObjectManagerDecoratorTest.php
@@ -100,7 +100,7 @@ public function testFlush(): void
 
     public function testGetRepository(): void
     {
-        $repository = $this->createMock(ObjectRepository::class);
+        $repository = self::createStub(ObjectRepository::class);
 
         $this->wrapped->expects(self::once())
             ->method('getRepository')
@@ -112,7 +112,7 @@ public function testGetRepository(): void
 
     public function testGetClassMetadata(): void
     {
-        $classMetadata = $this->createMock(ClassMetadata::class);
+        $classMetadata = self::createStub(ClassMetadata::class);
 
         $this->wrapped->expects(self::once())
             ->method('getClassMetadata')
@@ -124,7 +124,7 @@ public function testGetClassMetadata(): void
 
     public function testGetClassMetadataFactory(): void
     {
-        $classMetadataFactory = $this->createMock(ClassMetadataFactory::class);
+        $classMetadataFactory = self::createStub(ClassMetadataFactory::class);
 
         $this->wrapped->expects(self::once())
             ->method('getMetadataFactory')
diff --git a/tests/Reflection/TypedNoDefaultReflectionPropertyTest.php b/tests/Reflection/TypedNoDefaultReflectionPropertyTest.php
index 3b3f41ee..244adff7 100644
--- a/tests/Reflection/TypedNoDefaultReflectionPropertyTest.php
+++ b/tests/Reflection/TypedNoDefaultReflectionPropertyTest.php
@@ -72,7 +72,7 @@ public function setId(mixed $id): void
 
 class TypedNullableFoo
 {
-    private string|null $value;
+    private string|null $value = null;
 
     public function setValue(mixed $value): void
     {
diff --git a/tests/RuntimeReflectionPropertyTest.php b/tests/RuntimeReflectionPropertyTest.php
index 90a7241d..030de88a 100644
--- a/tests/RuntimeReflectionPropertyTest.php
+++ b/tests/RuntimeReflectionPropertyTest.php
@@ -40,8 +40,8 @@ public function testGetSetValue(string $name, string $value): void
     }
 
     /** @param class-string<RuntimeReflectionPropertyTestProxyMock> $proxyClass */
-    #[TestWith(['Doctrine\\Tests\\Persistence\\RuntimeReflectionPropertyTestProxyMock'])]
-    #[TestWith(['\\Doctrine\\Tests\\Persistence\\RuntimeReflectionPropertyTestProxyMock'])]
+    #[TestWith([RuntimeReflectionPropertyTestProxyMock::class])]
+    #[TestWith([RuntimeReflectionPropertyTestProxyMock::class])]
     public function testGetValueOnProxyProperty(string $proxyClass): void
     {
         $getCheckMock = $this->createMock(DummyMock::class);