diff --git a/core/modules/language/tests/src/Unit/Plugin/LanguageNegotiation/LanguageNegotiationContentEntityTest.php b/core/modules/language/tests/src/Unit/Plugin/LanguageNegotiation/LanguageNegotiationContentEntityTest.php
index fac7885f7bf1470d8114873fac7be67a89237629..e62321169462de8d1dae9549462ef775ffd1af0f 100644
--- a/core/modules/language/tests/src/Unit/Plugin/LanguageNegotiation/LanguageNegotiationContentEntityTest.php
+++ b/core/modules/language/tests/src/Unit/Plugin/LanguageNegotiation/LanguageNegotiationContentEntityTest.php
@@ -57,17 +57,17 @@ protected function setUp(): void {
     $language_de = $this->createMock(LanguageInterface::class);
     $language_de->expects($this->any())
       ->method('getId')
-      ->will($this->returnValue('de'));
+      ->willReturn('de');
     $language_de->expects($this->any())
       ->method('getName')
-      ->will($this->returnValue('German'));
+      ->willReturn('German');
     $language_en = $this->createMock(LanguageInterface::class);
     $language_en->expects($this->any())
       ->method('getId')
-      ->will($this->returnValue('en'));
+      ->willReturn('en');
     $language_en->expects($this->any())
       ->method('getName')
-      ->will($this->returnValue('English'));
+      ->willReturn('English');
     $this->languages = [
       'de' => $language_de,
       'en' => $language_en,
@@ -76,10 +76,10 @@ protected function setUp(): void {
     $language_manager = $this->createMock(ConfigurableLanguageManagerInterface::class);
     $language_manager->expects($this->any())
       ->method('getLanguages')
-      ->will($this->returnValue($this->languages));
+      ->willReturn($this->languages);
     $language_manager->expects($this->any())
       ->method('getNativeLanguages')
-      ->will($this->returnValue($this->languages));
+      ->willReturn($this->languages);
     $this->languageManager = $language_manager;
 
     $container = new ContainerBuilder();
@@ -167,10 +167,10 @@ public function testProcessOutbound() {
       ['hasLowerLanguageNegotiationWeight', 'meetsContentEntityRoutesCondition', 'getLangcode']);
     $languageNegotiationContentEntityMock->expects($this->any())
       ->method('hasLowerLanguageNegotiationWeight')
-      ->will($this->returnValue(TRUE));
+      ->willReturn(TRUE);
     $languageNegotiationContentEntityMock->expects($this->any())
       ->method('meetsContentEntityRoutesCondition')
-      ->will($this->returnValue(TRUE));
+      ->willReturn(TRUE);
     $languageNegotiationContentEntityMock->expects($this->exactly(2))
       ->method('getLangcode')
       ->willReturnOnConsecutiveCalls(
diff --git a/core/modules/link/tests/src/Unit/LinkFormatterTest.php b/core/modules/link/tests/src/Unit/LinkFormatterTest.php
index c86e1d9bf7a8884b874112233fff71ba0778b7af..c4867bff3a7822e7a4dff8da81fa05a4b9959f8b 100644
--- a/core/modules/link/tests/src/Unit/LinkFormatterTest.php
+++ b/core/modules/link/tests/src/Unit/LinkFormatterTest.php
@@ -49,7 +49,7 @@ public function testFormatterLinkItemUrlMalformed() {
     $fieldTypePluginManager = $this->createMock(FieldTypePluginManagerInterface::class);
     $fieldTypePluginManager->expects($this->once())
       ->method('createFieldItem')
-      ->will($this->returnValue($linkItem));
+      ->willReturn($linkItem);
     $urlGenerator = $this->createMock(UrlGenerator::class);
     $urlGenerator->expects($this->once())
       ->method('generateFromRoute')
@@ -91,7 +91,7 @@ public function testFormatterLinkItemUrlUnexpectedException() {
     $fieldTypePluginManager = $this->createMock(FieldTypePluginManagerInterface::class);
     $fieldTypePluginManager->expects($this->once())
       ->method('createFieldItem')
-      ->will($this->returnValue($linkItem));
+      ->willReturn($linkItem);
     $container = new ContainerBuilder();
     $container->set('plugin.manager.field.field_type', $fieldTypePluginManager);
     \Drupal::setContainer($container);
@@ -128,7 +128,7 @@ public function testFormatterLinkItem() {
     $fieldTypePluginManager = $this->createMock(FieldTypePluginManagerInterface::class);
     $fieldTypePluginManager->expects($this->once())
       ->method('createFieldItem')
-      ->will($this->returnValue($linkItem));
+      ->willReturn($linkItem);
     $urlGenerator = $this->createMock(UrlGenerator::class);
     $urlGenerator->expects($this->once())
       ->method('generateFromRoute')
diff --git a/core/modules/system/tests/src/Unit/Menu/SystemLocalTasksTest.php b/core/modules/system/tests/src/Unit/Menu/SystemLocalTasksTest.php
index 11564a2aca3269e27bdc7f5fae40a3753581c986..735d3513210a614870dd43291ae869a64ed5367c 100644
--- a/core/modules/system/tests/src/Unit/Menu/SystemLocalTasksTest.php
+++ b/core/modules/system/tests/src/Unit/Menu/SystemLocalTasksTest.php
@@ -54,7 +54,7 @@ protected function setUp(): void {
       ->expects($this->once())
       ->method('hasLinkTemplate')
       ->with('version-history')
-      ->will($this->returnValue(TRUE));
+      ->willReturn(TRUE);
     $entityTypeManager = $this->createMock(EntityTypeManagerInterface::class);
     $entityTypeManager->expects($this->any())
       ->method('getDefinitions')
diff --git a/core/modules/update/tests/src/Unit/UpdateMailTest.php b/core/modules/update/tests/src/Unit/UpdateMailTest.php
index b79df48c95008d928ebeb84fcc2af8b433839796..5e46b751b20fefddd2d0aaa9289c0c651a1cee20 100644
--- a/core/modules/update/tests/src/Unit/UpdateMailTest.php
+++ b/core/modules/update/tests/src/Unit/UpdateMailTest.php
@@ -114,10 +114,10 @@ public function testUpdateEmail($notification_threshold, $params, $authorized, a
     $this->configFactory
       ->expects($this->exactly(2))
       ->method('get')
-      ->will($this->returnValueMap([
+      ->willReturnMap([
         ['system.site', $config_site_name],
         ['update.settings', $config_notification],
-      ]));
+      ]);
 
     // The calls to generateFromRoute differ if authorized.
     $count = 2;
@@ -133,11 +133,11 @@ public function testUpdateEmail($notification_threshold, $params, $authorized, a
     $this->urlGenerator
       ->expects($this->exactly($count))
       ->method('generateFromRoute')
-      ->will($this->returnValueMap([
+      ->willReturnMap([
         ['update.status', [], ['absolute' => TRUE, 'language' => $langcode], FALSE, $update_settings_url],
         ['update.settings', [], ['absolute' => TRUE], FALSE, $available_updates_url],
         ['update.report_update', [], ['absolute' => TRUE, 'language' => $langcode], FALSE, $available_updates_url],
-      ]));
+      ]);
 
     // Set the container.
     $this->container->set('language_manager', $this->languageManager);
diff --git a/core/modules/views/tests/src/Unit/Plugin/pager/SqlBaseTest.php b/core/modules/views/tests/src/Unit/Plugin/pager/SqlBaseTest.php
index a51f267792f65ab949331cecf7c66ffb7c4e350d..a56d8e409d106ab3295253cfa08a56a2e9c1cbfc 100644
--- a/core/modules/views/tests/src/Unit/Plugin/pager/SqlBaseTest.php
+++ b/core/modules/views/tests/src/Unit/Plugin/pager/SqlBaseTest.php
@@ -74,7 +74,7 @@ public function testQuery() {
     ]);
     $this->view->expects($this->any())
       ->method('getRequest')
-      ->will($this->returnValue($request));
+      ->willReturn($request);
 
     $options = [];
     $this->pager->init($this->view, $this->display, $options);
diff --git a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendFactoryTest.php b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendFactoryTest.php
index 6b14a97c3a82b8873caf1af2315e16445b2f6ae7..436db6dc00c09feee721f28236b3223641daaaf2 100644
--- a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendFactoryTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendFactoryTest.php
@@ -56,13 +56,13 @@ public function testDifferentServices() {
 
     $container->expects($this->exactly(2))
       ->method('get')
-      ->will(
-        $this->returnCallback(function ($service) use ($testFastCacheFactory, $testConsistentCacheFactory) {
+      ->willReturnCallback(
+        function ($service) use ($testFastCacheFactory, $testConsistentCacheFactory) {
           return match ($service) {
             'cache.backend.test_consistent' => $testConsistentCacheFactory,
             'cache.backend.test_fast' => $testFastCacheFactory,
           };
-        })
+        }
       );
 
     // The same bin should be retrieved from both backends.
diff --git a/core/tests/Drupal/Tests/Core/Config/StorageComparerTest.php b/core/tests/Drupal/Tests/Core/Config/StorageComparerTest.php
index aaf6d9dc27c4343b2cc1c46be7da12c4e49c22a4..a3c7e63fea22d3c36fcf434113191d5bee058582 100644
--- a/core/tests/Drupal/Tests/Core/Config/StorageComparerTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/StorageComparerTest.php
@@ -51,10 +51,10 @@ protected function setUp(): void {
 
     $this->sourceStorage->expects($this->atLeastOnce())
       ->method('getCollectionName')
-      ->will($this->returnValue(StorageInterface::DEFAULT_COLLECTION));
+      ->willReturn(StorageInterface::DEFAULT_COLLECTION);
     $this->targetStorage->expects($this->atLeastOnce())
       ->method('getCollectionName')
-      ->will($this->returnValue(StorageInterface::DEFAULT_COLLECTION));
+      ->willReturn(StorageInterface::DEFAULT_COLLECTION);
 
     $this->storageComparer = new StorageComparer($this->sourceStorage, $this->targetStorage);
   }
diff --git a/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
index 41ca72ba1ff709d29545eef569f618e49f161b8e..40111e41eec7375f32b72afa6479d54a6581e737 100644
--- a/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
+++ b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
@@ -36,10 +36,10 @@ protected function setUp(): void {
     $language = new Language(['langcode' => 'en']);
     $this->languageManager->expects($this->any())
       ->method('getDefaultLanguage')
-      ->will($this->returnValue($language));
+      ->willReturn($language);
     $this->languageManager->expects($this->any())
       ->method('getCurrentLanguage')
-      ->will($this->returnValue($language));
+      ->willReturn($language);
     $container->set('language_manager', $this->languageManager);
 
     \Drupal::setContainer($container);