Issue #3427999 by andypost, Ayesh, bbrala: [PHP 8.4] Fix implicitly nullable type declarations

31 files changed, 66 insertions, 66 deletions

diff --git a/core/tests/Drupal/BuildTests/Framework/BuildTestBase.php b/core/tests/Drupal/BuildTests/Framework/BuildTestBase.php
index afdd7fcbcb5..11774331a81 100644
--- a/core/tests/Drupal/BuildTests/Framework/BuildTestBase.php
+++ b/core/tests/Drupal/BuildTests/Framework/BuildTestBase.php
@@ -547,7 +547,7 @@ abstract class BuildTestBase extends TestCase {
    *   (optional) Relative path within the test workspace file system that will
    *   contain the copy of the codebase. Defaults to the workspace directory.
    */
-  public function copyCodebase(\Iterator $iterator = NULL, $working_dir = NULL) {
+  public function copyCodebase(?\Iterator $iterator = NULL, $working_dir = NULL) {
     $working_path = $this->getWorkingPath($working_dir);
 
     if ($iterator === NULL) {
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
index 96484e3c46b..2086e2783c0 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
@@ -593,7 +593,7 @@ JS;
    * @param int $timeout
    *   Optional timeout in milliseconds, defaults to 10000.
    */
-  public function statusMessageExistsAfterWait(string $type = NULL, int $timeout = 10000): void {
+  public function statusMessageExistsAfterWait(?string $type = NULL, int $timeout = 10000): void {
     $selector = $this->buildJavascriptStatusMessageSelector(NULL, $type);
     $status_message_element = $this->waitForElement('xpath', $selector, $timeout);
     if ($type) {
@@ -615,7 +615,7 @@ JS;
    * @param int $timeout
    *   Optional timeout in milliseconds, defaults to 10000.
    */
-  public function statusMessageNotExistsAfterWait(string $type = NULL, int $timeout = 10000): void {
+  public function statusMessageNotExistsAfterWait(?string $type = NULL, int $timeout = 10000): void {
     $selector = $this->buildJavascriptStatusMessageSelector(NULL, $type);
     $status_message_element = $this->waitForElement('xpath', $selector, $timeout);
     if ($type) {
@@ -637,7 +637,7 @@ JS;
    * @param int $timeout
    *   Optional timeout in milliseconds, defaults to 10000.
    */
-  public function statusMessageContainsAfterWait(string $message, string $type = NULL, int $timeout = 10000): void {
+  public function statusMessageContainsAfterWait(string $message, ?string $type = NULL, int $timeout = 10000): void {
     $selector = $this->buildJavascriptStatusMessageSelector($message, $type);
     $status_message_element = $this->waitForElement('xpath', $selector, $timeout);
     if ($type) {
@@ -661,7 +661,7 @@ JS;
    * @param int $timeout
    *   Optional timeout in milliseconds, defaults to 10000.
    */
-  public function statusMessageNotContainsAfterWait(string $message, string $type = NULL, int $timeout = 10000): void {
+  public function statusMessageNotContainsAfterWait(string $message, ?string $type = NULL, int $timeout = 10000): void {
     $selector = $this->buildJavascriptStatusMessageSelector($message, $type);
     $status_message_element = $this->waitForElement('xpath', $selector, $timeout);
     if ($type) {
@@ -691,7 +691,7 @@ JS;
    * @throws \InvalidArgumentException
    *   Thrown when $type is not an allowed type.
    */
-  private function buildJavascriptStatusMessageSelector(string $message = NULL, string $type = NULL): string {
+  private function buildJavascriptStatusMessageSelector(?string $message = NULL, ?string $type = NULL): string {
     $allowed_types = [
       'status',
       'error',
diff --git a/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php b/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
index 470596a8751..dd0fdbd9614 100644
--- a/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
+++ b/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
@@ -130,7 +130,7 @@ class AssetOptimizationTest extends BrowserTestBase {
    * @param string|null $content_type
    *   The expected content type, or NULL to skip checking.
    */
-  protected function assertAggregate(string $url, bool $from_php = TRUE, string $content_type = NULL): void {
+  protected function assertAggregate(string $url, bool $from_php = TRUE, ?string $content_type = NULL): void {
     $url = $this->getAbsoluteUrl($url);
     if (!stripos($url, $this->fileAssetsPath) !== FALSE) {
       return;
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
index 3d057a79319..9fd06a29d39 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
@@ -306,7 +306,7 @@ class LibraryDiscoveryIntegrationTest extends KernelTestBase {
    *
    * @internal
    */
-  protected function assertAssetInLibrary(string $asset, string $extension, string $library_name, string $sub_key, string $message = NULL): void {
+  protected function assertAssetInLibrary(string $asset, string $extension, string $library_name, string $sub_key, ?string $message = NULL): void {
     if (!isset($message)) {
       $message = sprintf('Asset %s found in library "%s/%s"', $asset, $extension, $library_name);
     }
@@ -335,7 +335,7 @@ class LibraryDiscoveryIntegrationTest extends KernelTestBase {
    *
    * @internal
    */
-  protected function assertNoAssetInLibrary(string $asset, string $extension, string $library_name, string $sub_key, string $message = NULL): void {
+  protected function assertNoAssetInLibrary(string $asset, string $extension, string $library_name, string $sub_key, ?string $message = NULL): void {
     if (!isset($message)) {
       $message = sprintf('Asset %s not found in library "%s/%s"', $asset, $extension, $library_name);
     }
diff --git a/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificSchemaTestBase.php b/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificSchemaTestBase.php
index 3c520012d27..d8f410aca2b 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificSchemaTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificSchemaTestBase.php
@@ -53,7 +53,7 @@ abstract class DriverSpecificSchemaTestBase extends DriverSpecificKernelTestBase
    * @param string|null $column
    *   Optional column to test.
    */
-  abstract public function checkSchemaComment(string $description, string $table, string $column = NULL): void;
+  abstract public function checkSchemaComment(string $description, string $table, ?string $column = NULL): void;
 
   /**
    * Tests inserting data into an existing table.
diff --git a/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificTransactionTestBase.php b/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificTransactionTestBase.php
index 609fda1bf2d..6fd3182ea27 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificTransactionTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/DriverSpecificTransactionTestBase.php
@@ -492,7 +492,7 @@ class DriverSpecificTransactionTestBase extends DriverSpecificDatabaseTestBase {
    *
    * @internal
    */
-  public function assertRowPresent(string $name, string $message = NULL): void {
+  public function assertRowPresent(string $name, ?string $message = NULL): void {
     $present = (boolean) $this->connection->query('SELECT 1 FROM {test} WHERE [name] = :name', [':name' => $name])->fetchField();
     $this->assertTrue($present, $message ?? "Row '{$name}' should be present, but it actually does not exist.");
   }
@@ -507,7 +507,7 @@ class DriverSpecificTransactionTestBase extends DriverSpecificDatabaseTestBase {
    *
    * @internal
    */
-  public function assertRowAbsent(string $name, string $message = NULL): void {
+  public function assertRowAbsent(string $name, ?string $message = NULL): void {
     $present = (boolean) $this->connection->query('SELECT 1 FROM {test} WHERE [name] = :name', [':name' => $name])->fetchField();
     $this->assertFalse($present, $message ?? "Row '{$name}' should be absent, but it actually exists.");
   }
diff --git a/core/tests/Drupal/KernelTests/Core/Datetime/DatelistElementFormTest.php b/core/tests/Drupal/KernelTests/Core/Datetime/DatelistElementFormTest.php
index ffb9f5540df..eb8dd5f64b1 100644
--- a/core/tests/Drupal/KernelTests/Core/Datetime/DatelistElementFormTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Datetime/DatelistElementFormTest.php
@@ -44,7 +44,7 @@ class DatelistElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public function datelistDateCallbackTrusted(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public function datelistDateCallbackTrusted(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['datelistDateCallbackExecuted'] = [
       '#value' => TRUE,
     ];
@@ -54,7 +54,7 @@ class DatelistElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public function datelistDateCallback(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public function datelistDateCallback(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['datelistDateCallbackExecuted'] = [
       '#value' => TRUE,
     ];
diff --git a/core/tests/Drupal/KernelTests/Core/Datetime/DatetimeElementFormTest.php b/core/tests/Drupal/KernelTests/Core/Datetime/DatetimeElementFormTest.php
index 80689d3865a..12792adb067 100644
--- a/core/tests/Drupal/KernelTests/Core/Datetime/DatetimeElementFormTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Datetime/DatetimeElementFormTest.php
@@ -44,7 +44,7 @@ class DatetimeElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public function datetimeDateCallbackTrusted(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public function datetimeDateCallbackTrusted(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['datetimeDateCallbackExecuted'] = [
       '#value' => TRUE,
     ];
@@ -54,7 +54,7 @@ class DatetimeElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public static function datetimeDateCallback(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public static function datetimeDateCallback(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['datetimeDateCallbackExecuted'] = [
       '#value' => TRUE,
     ];
@@ -64,7 +64,7 @@ class DatetimeElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public function datetimeTimeCallbackTrusted(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public function datetimeTimeCallbackTrusted(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['timeCallbackExecuted'] = [
       '#value' => TRUE,
     ];
@@ -74,7 +74,7 @@ class DatetimeElementFormTest extends KernelTestBase implements FormInterface, T
   /**
    * {@inheritdoc}
    */
-  public static function datetimeTimeCallback(array &$element, FormStateInterface $form_state, DrupalDateTime $date = NULL) {
+  public static function datetimeTimeCallback(array &$element, FormStateInterface $form_state, ?DrupalDateTime $date = NULL) {
     $element['timeCallbackExecuted'] = [
       '#value' => TRUE,
     ];
@@ -159,7 +159,7 @@ class DatetimeElementFormTest extends KernelTestBase implements FormInterface, T
    * @dataProvider providerUntrusted
    * @group legacy
    */
-  public function testDatetimeElementUntrustedCallbacks(string $date_callback = 'datetimeDateCallbackTrusted', string $time_callback = 'datetimeTimeCallbackTrusted', string $expected_exception = NULL) : void {
+  public function testDatetimeElementUntrustedCallbacks(string $date_callback = 'datetimeDateCallbackTrusted', string $time_callback = 'datetimeTimeCallbackTrusted', ?string $expected_exception = NULL) : void {
     if ($expected_exception) {
       $this->expectException(UntrustedCallbackException::class);
       $this->expectExceptionMessage($expected_exception);
diff --git a/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php b/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
index e3d3b2f5d2e..37bda0da403 100644
--- a/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
+++ b/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
@@ -56,7 +56,7 @@ class DrupalKernelTest extends KernelTestBase {
    * @return \Drupal\Core\DrupalKernel
    *   New kernel for testing.
    */
-  protected function getTestKernel(Request $request, array $modules_enabled = NULL) {
+  protected function getTestKernel(Request $request, ?array $modules_enabled = NULL) {
     // Manually create kernel to avoid replacing settings.
     $class_loader = require $this->root . '/autoload.php';
     $kernel = DrupalKernel::createFromRequest($request, $class_loader, 'testing');
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityAccessControlHandlerTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityAccessControlHandlerTest.php
index 07c9797120f..933f8566f5e 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityAccessControlHandlerTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityAccessControlHandlerTest.php
@@ -43,7 +43,7 @@ class EntityAccessControlHandlerTest extends EntityLanguageTestBase {
    *
    * @internal
    */
-  public function assertEntityAccess(array $ops, AccessibleInterface $object, AccountInterface $account = NULL): void {
+  public function assertEntityAccess(array $ops, AccessibleInterface $object, ?AccountInterface $account = NULL): void {
     foreach ($ops as $op => $result) {
       $message = new FormattableMarkup("Entity access returns @result with operation '@op'.", [
         '@result' => !isset($result) ? 'null' : ($result ? 'true' : 'false'),
diff --git a/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php b/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php
index fd7dc6c6521..582f395ebfb 100644
--- a/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php
+++ b/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php
@@ -92,7 +92,7 @@ class TestSiteInstallCommand extends Command {
    * @todo Remove and fix test to not rely on super user.
    * @see https://www.drupal.org/project/drupal/issues/3437620
    */
-  public function __construct(string $name = NULL) {
+  public function __construct(?string $name = NULL) {
     parent::__construct($name);
     $this->usesSuperUserAccessPolicy = TRUE;
   }
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index 486e86def42..d0027e13743 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -526,7 +526,7 @@ abstract class BrowserTestBase extends TestCase {
    * @return array
    *   Associative array of option keys and values.
    */
-  protected function getOptions($select, Element $container = NULL) {
+  protected function getOptions($select, ?Element $container = NULL) {
     if (is_string($select)) {
       $select = $this->assertSession()->selectExists($select, $container);
     }
diff --git a/core/tests/Drupal/Tests/Component/ProxyBuilder/ProxyBuilderTest.php b/core/tests/Drupal/Tests/Component/ProxyBuilder/ProxyBuilderTest.php
index ed1f19a6868..271bef19ca0 100644
--- a/core/tests/Drupal/Tests/Component/ProxyBuilder/ProxyBuilderTest.php
+++ b/core/tests/Drupal/Tests/Component/ProxyBuilder/ProxyBuilderTest.php
@@ -432,7 +432,7 @@ class TestServiceMethodWithParameter {
 
 class TestServiceComplexMethod {
 
-  public function complexMethod(string $parameter, callable $function, TestServiceNoMethod $test_service = NULL, array &$elements = []): array {
+  public function complexMethod(string $parameter, callable $function, ?TestServiceNoMethod $test_service = NULL, array &$elements = []): array {
     return [];
   }
 
diff --git a/core/tests/Drupal/Tests/Component/Transliteration/PhpTransliterationTest.php b/core/tests/Drupal/Tests/Component/Transliteration/PhpTransliterationTest.php
index c50b832aa72..ce176d26299 100644
--- a/core/tests/Drupal/Tests/Component/Transliteration/PhpTransliterationTest.php
+++ b/core/tests/Drupal/Tests/Component/Transliteration/PhpTransliterationTest.php
@@ -91,7 +91,7 @@ class PhpTransliterationTest extends TestCase {
    *
    * @dataProvider providerTestPhpTransliteration
    */
-  public function testPhpTransliteration(string $langcode, string $original, string $expected, string $unknown_character = '?', int $max_length = NULL): void {
+  public function testPhpTransliteration(string $langcode, string $original, string $expected, string $unknown_character = '?', ?int $max_length = NULL): void {
     $transliterator_class = new PhpTransliteration();
     $actual = $transliterator_class->transliterate($original, $langcode, $unknown_character, $max_length);
     $this->assertSame($expected, $actual);
diff --git a/core/tests/Drupal/Tests/Component/Utility/XssTest.php b/core/tests/Drupal/Tests/Component/Utility/XssTest.php
index 27ed10a57c5..e25dd3e5dfc 100644
--- a/core/tests/Drupal/Tests/Component/Utility/XssTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/XssTest.php
@@ -68,7 +68,7 @@ class XssTest extends TestCase {
    *
    * @dataProvider providerTestFilterXssNormalized
    */
-  public function testFilterXssNormalized($value, $expected, $message, array $allowed_tags = NULL) {
+  public function testFilterXssNormalized($value, $expected, $message, ?array $allowed_tags = NULL) {
     if ($allowed_tags === NULL) {
       $value = Xss::filter($value);
     }
@@ -135,7 +135,7 @@ class XssTest extends TestCase {
    *
    * @dataProvider providerTestFilterXssNotNormalized
    */
-  public function testFilterXssNotNormalized($value, $expected, $message, array $allowed_tags = NULL) {
+  public function testFilterXssNotNormalized($value, $expected, $message, ?array $allowed_tags = NULL) {
     if ($allowed_tags === NULL) {
       $value = Xss::filter($value);
     }
diff --git a/core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Fixtures.php b/core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Fixtures.php
index b25c5072a98..624aaa59f6c 100644
--- a/core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Fixtures.php
+++ b/core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Fixtures.php
@@ -237,7 +237,7 @@ class Fixtures {
    *
    * @see \Drupal\Composer\Plugin\Scaffold\ScaffoldFilePath::destinationPath()
    */
-  public function destinationPath($destination, Interpolator $interpolator = NULL, $package_name = NULL) {
+  public function destinationPath($destination, ?Interpolator $interpolator = NULL, $package_name = NULL) {
     $interpolator = $interpolator ?: $this->getLocationReplacements();
     $package_name = $package_name ?: $interpolator->interpolate('[package-name]');
     return ScaffoldFilePath::destinationPath($package_name, $destination, $interpolator);
diff --git a/core/tests/Drupal/Tests/Core/Cache/VariationCacheTest.php b/core/tests/Drupal/Tests/Core/Cache/VariationCacheTest.php
index b53040970b2..64a11e90de4 100644
--- a/core/tests/Drupal/Tests/Core/Cache/VariationCacheTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/VariationCacheTest.php
@@ -492,7 +492,7 @@ class VariationCacheTest extends UnitTestCase {
    *   (optional) The cacheability that should have been used. Does not apply
    *   when checking for cache redirects.
    */
-  protected function assertCacheBackendItem(string $cid, $data, CacheableMetadata $cacheability = NULL) {
+  protected function assertCacheBackendItem(string $cid, $data, ?CacheableMetadata $cacheability = NULL) {
     $cache_backend_item = $this->memoryBackend->get($cid);
     $this->assertNotFalse($cache_backend_item, 'The data was stored and retrieved successfully.');
     $this->assertEquals($data, $cache_backend_item->data, 'Cache item contains the right data.');
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
index 49ae87a2cf9..f148e18af83 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
@@ -520,7 +520,7 @@ class BasicForm extends FormBase {
   /**
    * {@inheritdoc}
    */
-  public function buildForm(array $form, FormStateInterface $form_state, EntityInterface $entity_test = NULL) {
+  public function buildForm(array $form, FormStateInterface $form_state, ?EntityInterface $entity_test = NULL) {
     return [];
   }
 
@@ -571,7 +571,7 @@ class BasicFormNoContainerInjectionInterface implements FormInterface {
   /**
    * {@inheritdoc}
    */
-  public function buildForm(array $form, FormStateInterface $form_state, EntityInterface $entity_test = NULL) {
+  public function buildForm(array $form, FormStateInterface $form_state, ?EntityInterface $entity_test = NULL) {
     return [];
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php b/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
index 70c7358bf01..629ebc8dc2e 100644
--- a/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
+++ b/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
@@ -25,7 +25,7 @@ class FieldItemListTest extends UnitTestCase {
    *
    * @dataProvider providerTestEquals
    */
-  public function testEquals($expected, FieldItemInterface $first_field_item = NULL, FieldItemInterface $second_field_item = NULL) {
+  public function testEquals($expected, ?FieldItemInterface $first_field_item = NULL, ?FieldItemInterface $second_field_item = NULL) {
 
     // Mock the field type manager and place it in the container.
     $field_type_manager = $this->createMock('Drupal\Core\Field\FieldTypePluginManagerInterface');
@@ -167,7 +167,7 @@ class FieldItemListTest extends UnitTestCase {
    *
    * @dataProvider providerTestEquals
    */
-  public function testHasAffectingChanges($expected, FieldItemInterface $first_field_item = NULL, FieldItemInterface $second_field_item = NULL) {
+  public function testHasAffectingChanges($expected, ?FieldItemInterface $first_field_item = NULL, ?FieldItemInterface $second_field_item = NULL) {
     // Mock the field type manager and place it in the container.
     $field_type_manager = $this->createMock(FieldTypePluginManagerInterface::class);
     $container = new ContainerBuilder();
diff --git a/core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php b/core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php
index 5e9c909e4a3..c1f253096a1 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php
@@ -192,7 +192,7 @@ class EntityContextDefinitionIsSatisfiedTest extends UnitTestCase {
    *
    * @dataProvider providerTestIsSatisfiedByGenerateBundledEntity
    */
-  public function testIsSatisfiedByGenerateBundledEntity($expected, array $requirement_bundles, array $candidate_bundles, array $bundles_to_instantiate = NULL) {
+  public function testIsSatisfiedByGenerateBundledEntity($expected, array $requirement_bundles, array $candidate_bundles, ?array $bundles_to_instantiate = NULL) {
     // If no bundles are explicitly specified, instantiate all bundles.
     if (!$bundles_to_instantiate) {
       $bundles_to_instantiate = $candidate_bundles;
diff --git a/core/tests/Drupal/Tests/Core/Plugin/DefaultSingleLazyPluginCollectionTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultSingleLazyPluginCollectionTest.php
index c290c873346..43ccb8fd864 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/DefaultSingleLazyPluginCollectionTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultSingleLazyPluginCollectionTest.php
@@ -18,7 +18,7 @@ class DefaultSingleLazyPluginCollectionTest extends LazyPluginCollectionTestBase
   /**
    * {@inheritdoc}
    */
-  protected function setupPluginCollection(InvocationOrder $create_count = NULL) {
+  protected function setupPluginCollection(?InvocationOrder $create_count = NULL) {
     $definitions = $this->getPluginDefinitions();
     $this->pluginInstances['apple'] = new ConfigurablePlugin(['id' => 'apple', 'key' => 'value'], 'apple', $definitions['apple']);
     $this->pluginInstances['banana'] = new ConfigurablePlugin(['id' => 'banana', 'key' => 'other_value'], 'banana', $definitions['banana']);
diff --git a/core/tests/Drupal/Tests/Core/Plugin/LazyPluginCollectionTestBase.php b/core/tests/Drupal/Tests/Core/Plugin/LazyPluginCollectionTestBase.php
index d14cff7867f..a4f169b1565 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/LazyPluginCollectionTestBase.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/LazyPluginCollectionTestBase.php
@@ -66,7 +66,7 @@ abstract class LazyPluginCollectionTestBase extends UnitTestCase {
    *   called. For example, $this->any(), $this->once(), $this->exactly(6).
    *   Defaults to $this->never().
    */
-  protected function setupPluginCollection(InvocationOrder $create_count = NULL) {
+  protected function setupPluginCollection(?InvocationOrder $create_count = NULL) {
     $this->pluginInstances = [];
     $map = [];
     foreach ($this->getPluginDefinitions() as $plugin_id => $definition) {
diff --git a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
index 4f001bfda58..3acf540c4b5 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
@@ -29,7 +29,7 @@ class TestPluginManager extends DefaultPluginManager {
    * @param string $interface
    *   (optional) The interface required for the plugins.
    */
-  public function __construct(\Traversable $namespaces, array $definitions, ModuleHandlerInterface $module_handler = NULL, $alter_hook = NULL, $interface = NULL) {
+  public function __construct(\Traversable $namespaces, array $definitions, ?ModuleHandlerInterface $module_handler = NULL, $alter_hook = NULL, $interface = NULL) {
     // Create the object that can be used to return definitions for all the
     // plugins available for this type. Most real plugin managers use a richer
     // discovery implementation, but StaticDiscovery lets us add some simple
diff --git a/core/tests/Drupal/Tests/Core/ProxyBuilder/ProxyBuilderTest.php b/core/tests/Drupal/Tests/Core/ProxyBuilder/ProxyBuilderTest.php
index 969c70a345d..8f2c03d76d7 100644
--- a/core/tests/Drupal/Tests/Core/ProxyBuilder/ProxyBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/ProxyBuilder/ProxyBuilderTest.php
@@ -167,7 +167,7 @@ class TestServiceNoMethod {
 
 class TestServiceComplexMethod {
 
-  public function complexMethod($parameter, callable $function, TestServiceNoMethod $test_service = NULL, array &$elements = []) {
+  public function complexMethod($parameter, callable $function, ?TestServiceNoMethod $test_service = NULL, array &$elements = []) {
 
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Render/RendererTest.php b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
index 552fbee231d..d14a083c177 100644
--- a/core/tests/Drupal/Tests/Core/Render/RendererTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
@@ -41,7 +41,7 @@ class RendererTest extends RendererTestBase {
    *
    * @dataProvider providerTestRenderBasic
    */
-  public function testRenderBasic($build, $expected, callable $setup_code = NULL) {
+  public function testRenderBasic($build, $expected, ?callable $setup_code = NULL) {
     if (isset($setup_code)) {
       $setup_code = $setup_code->bindTo($this);
       $setup_code($this->themeManager);
diff --git a/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
index e35d06a7306..068f13f23b7 100644
--- a/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
@@ -515,7 +515,7 @@ class UrlGeneratorTest extends UnitTestCase {
     $path_processor = $this->createMock(OutboundPathProcessorInterface::CLASS);
     $path_processor->expects($this->atLeastOnce())
       ->method('processOutbound')
-      ->willReturnCallback(function ($path, &$options = [], Request $request = NULL, BubbleableMetadata $bubbleable_metadata = NULL) {
+      ->willReturnCallback(function ($path, &$options = [], ?Request $request = NULL, ?BubbleableMetadata $bubbleable_metadata = NULL) {
         $options['query'] = ['zoo' => 5];
         $options['fragment'] = 'foo';
         return $path;
diff --git a/core/tests/Drupal/Tests/Core/Security/RequestSanitizerTest.php b/core/tests/Drupal/Tests/Core/Security/RequestSanitizerTest.php
index 070f1d12631..b7f55934346 100644
--- a/core/tests/Drupal/Tests/Core/Security/RequestSanitizerTest.php
+++ b/core/tests/Drupal/Tests/Core/Security/RequestSanitizerTest.php
@@ -60,7 +60,7 @@ class RequestSanitizerTest extends UnitTestCase {
    *
    * @dataProvider providerTestRequestSanitization
    */
-  public function testRequestSanitization(Request $request, array $expected = [], array $expected_errors = NULL, array $whitelist = []) {
+  public function testRequestSanitization(Request $request, array $expected = [], ?array $expected_errors = NULL, array $whitelist = []) {
     // Set up globals.
     $_GET = $request->query->all();
     $_POST = $request->request->all();
diff --git a/core/tests/Drupal/Tests/Core/Session/AccessPolicyProcessorTest.php b/core/tests/Drupal/Tests/Core/Session/AccessPolicyProcessorTest.php
index a3d0b64d2b5..ebd6002999c 100644
--- a/core/tests/Drupal/Tests/Core/Session/AccessPolicyProcessorTest.php
+++ b/core/tests/Drupal/Tests/Core/Session/AccessPolicyProcessorTest.php
@@ -369,11 +369,11 @@ class AccessPolicyProcessorTest extends UnitTestCase {
    * @return \Drupal\Core\Session\AccessPolicyProcessorInterface
    */
   protected function setUpAccessPolicyProcessor(
-    VariationCacheInterface $variation_cache = NULL,
-    VariationCacheInterface $variation_cache_static = NULL,
-    CacheBackendInterface $cache_static = NULL,
-    AccountProxyInterface $current_user = NULL,
-    AccountSwitcherInterface $account_switcher = NULL,
+    ?VariationCacheInterface $variation_cache = NULL,
+    ?VariationCacheInterface $variation_cache_static = NULL,
+    ?CacheBackendInterface $cache_static = NULL,
+    ?AccountProxyInterface $current_user = NULL,
+    ?AccountSwitcherInterface $account_switcher = NULL,
   ) {
     // Prophecy does not accept a willReturn call on a mocked method if said
     // method has a return type of void. However, without willReturn() or any
diff --git a/core/tests/Drupal/Tests/Core/Utility/UnroutedUrlAssemblerTest.php b/core/tests/Drupal/Tests/Core/Utility/UnroutedUrlAssemblerTest.php
index a1a6aed5c92..d0eb9c871a7 100644
--- a/core/tests/Drupal/Tests/Core/Utility/UnroutedUrlAssemblerTest.php
+++ b/core/tests/Drupal/Tests/Core/Utility/UnroutedUrlAssemblerTest.php
@@ -154,7 +154,7 @@ class UnroutedUrlAssemblerTest extends UnitTestCase {
     $this->setupRequestStack(FALSE);
     $this->pathProcessor->expects($this->exactly(2))
       ->method('processOutbound')
-      ->willReturnCallback(function ($path, &$options = [], Request $request = NULL, BubbleableMetadata $bubbleable_metadata = NULL) {
+      ->willReturnCallback(function ($path, &$options = [], ?Request $request = NULL, ?BubbleableMetadata $bubbleable_metadata = NULL) {
         if ($bubbleable_metadata) {
           $bubbleable_metadata->setCacheContexts(['some-cache-context']);
         }
@@ -179,7 +179,7 @@ class UnroutedUrlAssemblerTest extends UnitTestCase {
     $this->pathProcessor->expects($this->exactly(2))
       ->method('processOutbound')
       ->with('/test-uri', $this->anything(), $this->anything(), $this->anything())
-      ->willReturnCallback(function ($path, &$options = [], Request $request = NULL, BubbleableMetadata $bubbleable_metadata = NULL) {
+      ->willReturnCallback(function ($path, &$options = [], ?Request $request = NULL, ?BubbleableMetadata $bubbleable_metadata = NULL) {
         $bubbleable_metadata?->setCacheContexts(['some-cache-context']);
         return '/test-other-uri';
       });
diff --git a/core/tests/Drupal/Tests/PhpCs/SortTest.php b/core/tests/Drupal/Tests/PhpCs/SortTest.php
index 41ffab51b38..6927f442ccd 100644
--- a/core/tests/Drupal/Tests/PhpCs/SortTest.php
+++ b/core/tests/Drupal/Tests/PhpCs/SortTest.php
@@ -81,7 +81,7 @@ class SortTest extends TestCase {
    * @param null|string $column
    *   The column of the value or NULL.
    */
-  private function assertSorted(array $input, string $column = NULL) {
+  private function assertSorted(array $input, ?string $column = NULL) {
     $input_sorted = $input;
 
     if ($column === NULL) {
diff --git a/core/tests/Drupal/Tests/WebAssert.php b/core/tests/Drupal/Tests/WebAssert.php
index c3d2a69824f..a60597aa665 100644
--- a/core/tests/Drupal/Tests/WebAssert.php
+++ b/core/tests/Drupal/Tests/WebAssert.php
@@ -145,7 +145,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    *   When the element doesn't exist.
    */
-  public function buttonExists($button, TraversableElement $container = NULL) {
+  public function buttonExists($button, ?TraversableElement $container = NULL) {
     if (!is_string($button)) {
       // @todo Trigger deprecation in
       //   https://www.drupal.org/project/drupal/issues/3421105.
@@ -172,7 +172,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ExpectationException
    *   When the button exists.
    */
-  public function buttonNotExists($button, TraversableElement $container = NULL) {
+  public function buttonNotExists($button, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $node = $container->findButton($button);
 
@@ -193,7 +193,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    *   When the element doesn't exist.
    */
-  public function selectExists($select, TraversableElement $container = NULL) {
+  public function selectExists($select, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $node = $container->find('named', [
       'select',
@@ -223,7 +223,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    *   When the element doesn't exist.
    */
-  public function optionExists($select, $option, TraversableElement $container = NULL) {
+  public function optionExists($select, $option, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $select_field = $container->find('named', [
       'select',
@@ -256,7 +256,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    *   When the select element doesn't exist.
    */
-  public function optionNotExists($select, $option, TraversableElement $container = NULL) {
+  public function optionNotExists($select, $option, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $select_field = $container->find('named', [
       'select',
@@ -601,7 +601,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    * @throws \Behat\Mink\Exception\ExpectationException
    */
-  public function fieldDisabled($field, TraversableElement $container = NULL) {
+  public function fieldDisabled($field, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $node = $container->findField($field);
 
@@ -630,7 +630,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    * @throws \Behat\Mink\Exception\ExpectationException
    */
-  public function fieldEnabled($field, TraversableElement $container = NULL) {
+  public function fieldEnabled($field, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $node = $container->findField($field);
 
@@ -658,7 +658,7 @@ class WebAssert extends MinkWebAssert {
    *
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    */
-  public function hiddenFieldExists($field, TraversableElement $container = NULL) {
+  public function hiddenFieldExists($field, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     if ($node = $container->find('hidden_field_selector', ['hidden_field', $field])) {
       return $node;
@@ -676,7 +676,7 @@ class WebAssert extends MinkWebAssert {
    *
    * @throws \Behat\Mink\Exception\ExpectationException
    */
-  public function hiddenFieldNotExists($field, TraversableElement $container = NULL) {
+  public function hiddenFieldNotExists($field, ?TraversableElement $container = NULL) {
     $container = $container ?: $this->session->getPage();
     $node = $container->find('hidden_field_selector', ['hidden_field', $field]);
     $this->assert($node === NULL, "A hidden field '$field' exists on this page, but it should not.");
@@ -695,7 +695,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    * @throws \Behat\Mink\Exception\ExpectationException
    */
-  public function hiddenFieldValueEquals($field, $value, TraversableElement $container = NULL) {
+  public function hiddenFieldValueEquals($field, $value, ?TraversableElement $container = NULL) {
     $node = $this->hiddenFieldExists($field, $container);
     $actual = $node->getValue();
     $regex = '/^' . preg_quote($value, '/') . '$/ui';
@@ -716,7 +716,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \Behat\Mink\Exception\ElementNotFoundException
    * @throws \Behat\Mink\Exception\ExpectationException
    */
-  public function hiddenFieldValueNotEquals($field, $value, TraversableElement $container = NULL) {
+  public function hiddenFieldValueNotEquals($field, $value, ?TraversableElement $container = NULL) {
     $node = $this->hiddenFieldExists($field, $container);
     $actual = $node->getValue();
     $regex = '/^' . preg_quote($value, '/') . '$/ui';
@@ -813,7 +813,7 @@ class WebAssert extends MinkWebAssert {
    * @param string|null $type
    *   The optional message type: status, error, or warning.
    */
-  public function statusMessageExists(string $type = NULL): void {
+  public function statusMessageExists(?string $type = NULL): void {
     $selector = $this->buildStatusMessageSelector(NULL, $type);
     try {
       $this->elementExists('xpath', $selector);
@@ -829,7 +829,7 @@ class WebAssert extends MinkWebAssert {
    * @param string|null $type
    *   The optional message type: status, error, or warning.
    */
-  public function statusMessageNotExists(string $type = NULL): void {
+  public function statusMessageNotExists(?string $type = NULL): void {
     $selector = $this->buildStatusMessageSelector(NULL, $type);
     try {
       $this->elementNotExists('xpath', $selector);
@@ -847,7 +847,7 @@ class WebAssert extends MinkWebAssert {
    * @param string|null $type
    *   The optional message type: status, error, or warning.
    */
-  public function statusMessageContains(string $message, string $type = NULL): void {
+  public function statusMessageContains(string $message, ?string $type = NULL): void {
     $selector = $this->buildStatusMessageSelector($message, $type);
     try {
       $this->elementExists('xpath', $selector);
@@ -865,7 +865,7 @@ class WebAssert extends MinkWebAssert {
    * @param string|null $type
    *   The optional message type: status, error, or warning.
    */
-  public function statusMessageNotContains(string $message, string $type = NULL): void {
+  public function statusMessageNotContains(string $message, ?string $type = NULL): void {
     $selector = $this->buildStatusMessageSelector($message, $type);
     try {
       $this->elementNotExists('xpath', $selector);
@@ -894,7 +894,7 @@ class WebAssert extends MinkWebAssert {
    * @throws \InvalidArgumentException
    *   Thrown when $type is not an allowed type.
    */
-  protected function buildStatusMessageSelector(string $message = NULL, string $type = NULL): string {
+  protected function buildStatusMessageSelector(?string $message = NULL, ?string $type = NULL): string {
     $allowed_types = [
       'status',
       'error',
@@ -978,7 +978,7 @@ class WebAssert extends MinkWebAssert {
   /**
    * {@inheritdoc}
    */
-  public function fieldValueEquals(string $field, $value, TraversableElement $container = NULL) {
+  public function fieldValueEquals(string $field, $value, ?TraversableElement $container = NULL) {
     if (!is_string($value)) {
       // @todo Trigger deprecation in
       //   https://www.drupal.org/project/drupal/issues/3421105.