diff --git a/tests/TestCase/Form/FormTest.php b/tests/TestCase/Form/FormTest.php
index 99ec85a7e17..55c8a0cd817 100644
--- a/tests/TestCase/Form/FormTest.php
+++ b/tests/TestCase/Form/FormTest.php
@@ -20,6 +20,7 @@
 use Cake\Form\Schema;
 use Cake\TestSuite\TestCase;
 use Cake\Validation\Validator;
+use Exception;
 use TestApp\Form\AppForm;
 use TestApp\Form\FormSchema;
 
@@ -164,16 +165,18 @@ public function testSetErrors(): void
      */
     public function testExecuteInvalid(): void
     {
-        $form = $this->getMockBuilder(Form::class)
-            ->onlyMethods(['_execute'])
-            ->getMock();
+        $form = new class extends Form {
+            // phpcs:ignore CakePHP.NamingConventions.ValidFunctionName.PublicWithUnderscore
+            public function _execute(array $data): bool
+            {
+                throw new Exception('Should not be called');
+            }
+        };
         $form->getValidator()
             ->add('email', 'format', ['rule' => 'email']);
         $data = [
             'email' => 'rong',
         ];
-        $form->expects($this->never())
-            ->method('_execute');
 
         $this->assertFalse($form->execute($data));
     }
diff --git a/tests/TestCase/Http/Client/Auth/DigestTest.php b/tests/TestCase/Http/Client/Auth/DigestTest.php
index 05df2361cc4..5185b4e6d99 100644
--- a/tests/TestCase/Http/Client/Auth/DigestTest.php
+++ b/tests/TestCase/Http/Client/Auth/DigestTest.php
@@ -34,7 +34,7 @@ class DigestTest extends TestCase
     protected $client;
 
     /**
-     * @var \PHPUnit\Framework\MockObject\MockObject|\Cake\Http\Client\Auth\Digest
+     * @var \Cake\Http\Client\Auth\Digest
      */
     protected $auth;
 
@@ -50,19 +50,17 @@ public function setUp(): void
     }
 
     /**
-     * @return Digest|\PHPUnit\Framework\MockObject\MockObject
+     * @return Digest
      */
     protected function getDigestMock()
     {
-        $digest = $this->getMockBuilder(Digest::class)
-            ->onlyMethods(['generateCnonce'])
-            ->setConstructorArgs([$this->client])
-            ->getMock();
-        $digest->expects($this->any())
-            ->method('generateCnonce')
-            ->willReturn('cnonce');
-
-        return $digest;
+        return new class ($this->client) extends Digest
+        {
+            public function generateCnonce(): string
+            {
+                return 'cnonce';
+            }
+        };
     }
 
     /**
diff --git a/tests/TestCase/Http/ServerTest.php b/tests/TestCase/Http/ServerTest.php
index fb0ed3e9695..dc15b8498ea 100644
--- a/tests/TestCase/Http/ServerTest.php
+++ b/tests/TestCase/Http/ServerTest.php
@@ -33,6 +33,7 @@
 use Laminas\Diactoros\ServerRequest as LaminasServerRequest;
 use Mockery;
 use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
 use TestApp\Http\MiddlewareApplication;
 
 require_once __DIR__ . '/server_mocks.php';
@@ -84,14 +85,14 @@ public function tearDown(): void
      */
     public function testAppGetSet(): void
     {
-        /** @var \Cake\Http\BaseApplication|\PHPUnit\Framework\MockObject\MockObject $app */
-        $app = $this->getMockBuilder(BaseApplication::class)
-            ->setConstructorArgs([$this->config])
-            ->getMock();
-
-        $manager = new EventManager();
-        $app->method('getEventManager')
-            ->willReturn($manager);
+        $eventManager = new EventManager();
+        $app = new class ($this->config, $eventManager) extends BaseApplication
+        {
+            public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue
+            {
+                return $middlewareQueue;
+            }
+        };
 
         $server = new Server($app);
         $this->assertSame($app, $server->getApp());
@@ -319,8 +320,21 @@ public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue
      */
     public function testGetEventManagerNonEventedApplication(): void
     {
-        /** @var \Cake\Core\HttpApplicationInterface|\PHPUnit\Framework\MockObject\MockObject $app */
-        $app = $this->createMock(HttpApplicationInterface::class);
+        $app = new class implements HttpApplicationInterface {
+            public function bootstrap(): void
+            {
+            }
+
+            public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue
+            {
+                return $middlewareQueue;
+            }
+
+            public function handle(ServerRequestInterface $request): ResponseInterface
+            {
+                return new Response();
+            }
+        };
 
         $server = new Server($app);
         $this->assertSame(EventManager::instance(), $server->getEventManager());
@@ -331,8 +345,21 @@ public function testGetEventManagerNonEventedApplication(): void
      */
     public function testSetEventManagerNonEventedApplication(): void
     {
-        /** @var \Cake\Core\HttpApplicationInterface|\PHPUnit\Framework\MockObject\MockObject $app */
-        $app = $this->createMock(HttpApplicationInterface::class);
+        $app = new class implements HttpApplicationInterface {
+            public function bootstrap(): void
+            {
+            }
+
+            public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue
+            {
+                return $middlewareQueue;
+            }
+
+            public function handle(ServerRequestInterface $request): ResponseInterface
+            {
+                return new Response();
+            }
+        };
 
         $events = new EventManager();
         $server = new Server($app);
@@ -347,8 +374,21 @@ public function testSetEventManagerNonEventedApplication(): void
      */
     public function testAppWithoutContainerApplicationInterface(): void
     {
-        /** @var \Cake\Core\HttpApplicationInterface|\PHPUnit\Framework\MockObject\MockObject $app */
-        $app = $this->createMock(HttpApplicationInterface::class);
+        $app = new class implements HttpApplicationInterface {
+            public function bootstrap(): void
+            {
+            }
+
+            public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue
+            {
+                return $middlewareQueue;
+            }
+
+            public function handle(ServerRequestInterface $request): ResponseInterface
+            {
+                return new Response();
+            }
+        };
         $server = new Server($app);
 
         $request = new ServerRequest();
@@ -372,11 +412,12 @@ function ($event, $request, $response) use (&$triggered): void {
             }
         );
 
-        $emitter = $this->getMockBuilder(ResponseEmitter::class)->getMock();
-        $emitter->expects($this->once())
-            ->method('emit')
-            ->willReturn(true);
-
+        $emitter = new class extends ResponseEmitter {
+            public function emit(ResponseInterface $response, $stream = null): bool
+            {
+                return true;
+            }
+        };
         $server->emit(new Response(), $emitter);
 
         $this->assertTrue($triggered);
diff --git a/tests/TestCase/Mailer/MailerDefaultProfileRestorationTest.php b/tests/TestCase/Mailer/MailerDefaultProfileRestorationTest.php
index 347e0b7f6a3..55c871d2d09 100644
--- a/tests/TestCase/Mailer/MailerDefaultProfileRestorationTest.php
+++ b/tests/TestCase/Mailer/MailerDefaultProfileRestorationTest.php
@@ -21,27 +21,22 @@ class MailerDefaultProfileRestorationTest extends TestCase
 {
     public function testSendAction(): void
     {
-        $mailer = $this->getMockBuilder(DefaultProfileRestorationMailer::class)
-            ->onlyMethods(['deliver', 'test'])
-            ->setConstructorArgs([['template' => 'cakephp']])
-            ->getMock();
-        $mailer->expects($this->once())
-            ->method('test')
-            ->with('foo', 'bar');
-        $mailer->expects($this->once())
-            ->method('deliver')
-            ->willReturn([]);
+        $mailer = new class (['template' => 'cakephp']) extends Mailer {
+            public bool $testIsCalled = false;
+
+            public function test($to, $subject)
+            {
+                $this->testIsCalled = true;
+            }
+
+            public function deliver(string $content = ''): array
+            {
+                return [];
+            }
+        };
 
         $mailer->send('test', ['foo', 'bar']);
         $this->assertSame('cakephp', $mailer->viewBuilder()->getTemplate());
+        $this->assertTrue($mailer->testIsCalled);
     }
 }
-
-// phpcs:disable
-class DefaultProfileRestorationMailer extends Mailer
-{
-    public function test($to, $subject)
-    {
-    }
-}
-// phpcs:enable
diff --git a/tests/TestCase/Mailer/MailerSendActionTest.php b/tests/TestCase/Mailer/MailerSendActionTest.php
index ef64e304806..1f8f6a36db3 100644
--- a/tests/TestCase/Mailer/MailerSendActionTest.php
+++ b/tests/TestCase/Mailer/MailerSendActionTest.php
@@ -21,27 +21,23 @@ class MailerSendActionTest extends TestCase
 {
     public function testSendAction(): void
     {
-        $mailer = $this->getMockBuilder(SendActionMailer::class)
-            ->onlyMethods(['deliver', 'test'])
-            ->getMock();
-        $mailer->expects($this->once())
-            ->method('test')
-            ->with('foo', 'bar');
-        $mailer->expects($this->any())
-            ->method('deliver')
-            ->willReturn([]);
+        $mailer = new class extends Mailer {
+            public bool $testIsCalled = false;
+
+            public function test($to, $subject)
+            {
+                $this->testIsCalled = true;
+            }
+
+            public function deliver(string $content = ''): array
+            {
+                return [];
+            }
+        };
 
         $mailer->send('test', ['foo', 'bar']);
 
         $this->assertNull($mailer->viewBuilder()->getTemplate());
+        $this->assertTrue($mailer->testIsCalled);
     }
 }
-
-// phpcs:disable
-class SendActionMailer extends Mailer
-{
-    public function test($to, $subject)
-    {
-    }
-}
-// phpcs:enable
diff --git a/tests/TestCase/Mailer/MailerSendFailsEmailIsReset.php b/tests/TestCase/Mailer/MailerSendFailsEmailIsReset.php
index eca801ef459..2430f6c018a 100644
--- a/tests/TestCase/Mailer/MailerSendFailsEmailIsReset.php
+++ b/tests/TestCase/Mailer/MailerSendFailsEmailIsReset.php
@@ -22,31 +22,31 @@ class MailerSendFailsEmailIsReset extends TestCase
 {
     public function testSendAction(): void
     {
-        $mailer = $this->getMockBuilder(SendFailsEmailIsResetMailer::class)
-            ->onlyMethods(['restore', 'deliver', 'welcome'])
-            ->getMock();
+        $mailer = new class extends Mailer {
+            public bool $restoreIsCalled = false;
 
-        $mailer->expects($this->once())
-            ->method('deliver')
-            ->will($this->throwException(new RuntimeException('kaboom')));
-        // Mailer should be reset even if sending fails.
-        $mailer->expects($this->once())
-            ->method('restore');
+            public function welcome()
+            {
+            }
+
+            public function deliver(string $content = ''): array
+            {
+                throw new RuntimeException('kaboom');
+            }
+
+            protected function restore()
+            {
+                $this->restoreIsCalled = true;
+
+                return $this;
+            }
+        };
 
         try {
             $mailer->send('welcome', ['foo', 'bar']);
             $this->fail('Exception should bubble up.');
         } catch (RuntimeException) {
-            $this->assertTrue(true, 'Exception was raised');
+            $this->assertTrue($mailer->restoreIsCalled, 'Exception was raised');
         }
     }
 }
-
-// phpcs:disable
-class SendFailsEmailIsResetMailer extends Mailer
-{
-    public function welcome()
-    {
-    }
-}
-// phpcs:enable
diff --git a/tests/TestCase/Mailer/MailerSendWithUnsetTemplateDefaultsToActionNameTest.php b/tests/TestCase/Mailer/MailerSendWithUnsetTemplateDefaultsToActionNameTest.php
index 5346dc52f16..7011e24203f 100644
--- a/tests/TestCase/Mailer/MailerSendWithUnsetTemplateDefaultsToActionNameTest.php
+++ b/tests/TestCase/Mailer/MailerSendWithUnsetTemplateDefaultsToActionNameTest.php
@@ -21,26 +21,27 @@ class MailerSendWithUnsetTemplateDefaultsToActionNameTest extends TestCase
 {
     public function testSendAction(): void
     {
-        $mailer = $this->getMockBuilder(SendWithUnsetTemplateDefaultsToActionNameMailer::class)
-            ->onlyMethods(['deliver', 'restore', 'test'])
-            ->getMock();
-        $mailer->expects($this->once())
-            ->method('test')
-            ->with('foo', 'bar');
-        $mailer->expects($this->any())
-            ->method('deliver')
-            ->willReturn([]);
+        $mailer = new class extends Mailer {
+            public bool $testIsCalled = false;
+
+            public function test($to, $subject)
+            {
+                $this->testIsCalled = true;
+            }
+
+            public function deliver(string $content = ''): array
+            {
+                return [];
+            }
+
+            protected function restore()
+            {
+                return $this;
+            }
+        };
 
         $mailer->send('test', ['foo', 'bar']);
         $this->assertSame('test', $mailer->viewBuilder()->getTemplate());
+        $this->assertTrue($mailer->testIsCalled);
     }
 }
-
-// phpcs:disable
-class SendWithUnsetTemplateDefaultsToActionNameMailer extends Mailer
-{
-    public function test($to, $subject)
-    {
-    }
-}
-// phpcs:enable
diff --git a/tests/TestCase/Mailer/MailerTest.php b/tests/TestCase/Mailer/MailerTest.php
index 1a2f55f8684..421055e7f18 100644
--- a/tests/TestCase/Mailer/MailerTest.php
+++ b/tests/TestCase/Mailer/MailerTest.php
@@ -88,7 +88,8 @@ public function testTransport(): void
         $result = $this->mailer->getTransport();
         $this->assertInstanceOf(DebugTransport::class, $result);
 
-        $instance = $this->getMockBuilder(DebugTransport::class)->getMock();
+        $instance = new class extends DebugTransport {
+        };
         $this->mailer->setTransport($instance);
         $this->assertSame($instance, $this->mailer->getTransport());
     }
@@ -311,21 +312,26 @@ public function testUseConfigString(): void
     }
 
     /**
-     * CakeEmailTest::testMockTransport()
+     * CakeEmailTest::testDefaultTransport()
      */
-    public function testMockTransport(): void
+    public function testDefaultTransport(): void
     {
         TransportFactory::drop('default');
 
-        $mock = $this->getMockBuilder(AbstractTransport::class)->getMock();
+        $instance = new class extends AbstractTransport {
+            public function send(Message $message): array
+            {
+                return [];
+            }
+        };
         $config = ['from' => 'tester@example.org', 'transport' => 'default'];
 
         Mailer::setConfig('default', $config);
-        TransportFactory::setConfig('default', $mock);
+        TransportFactory::setConfig('default', $instance);
 
         $em = new Mailer('default');
 
-        $this->assertSame($mock, $em->getTransport());
+        $this->assertSame($instance, $em->getTransport());
 
         TransportFactory::drop('default');
     }