diff --git a/core/modules/media/tests/src/Functional/ProviderRepositoryTest.php b/core/modules/media/tests/src/Functional/ProviderRepositoryTest.php
index 2e81efc6b783eb88e32413889447a778cd592a5d..d791a2f90ea771df2dfd890b2a437150566b34c8 100644
--- a/core/modules/media/tests/src/Functional/ProviderRepositoryTest.php
+++ b/core/modules/media/tests/src/Functional/ProviderRepositoryTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\media\OEmbed\ProviderException;
 use GuzzleHttp\Psr7\Utils;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 /**
  * Tests the oEmbed provider repository.
@@ -14,6 +15,8 @@
  */
 class ProviderRepositoryTest extends MediaFunctionalTestBase {
 
+  use ProphecyTrait;
+
   /**
    * {@inheritdoc}
    */
diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index eab4a431aa08b3a90b6d3c6141e98561ea53db29..47fd9b5862843dc0e5dad8314989fb75fb31a932 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -26,6 +26,7 @@
 use Drupal\TestTools\TestVarDumper;
 use PHPUnit\Framework\Exception;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpFoundation\Request;
@@ -89,6 +90,7 @@ abstract class KernelTestBase extends TestCase implements ServiceProviderInterfa
   use TestRequirementsTrait;
   use PhpUnitWarnings;
   use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
   use ExpectDeprecationTrait;
 
   /**
diff --git a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit9/TestCompatibilityTrait.php b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit9/TestCompatibilityTrait.php
index 997f5e245f199e8e3301ffc6ff13e2b133c1c932..590fc337be2eb5dd3612389f99f5c8cc4bc06898 100644
--- a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit9/TestCompatibilityTrait.php
+++ b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit9/TestCompatibilityTrait.php
@@ -2,19 +2,9 @@
 
 namespace Drupal\TestTools\PhpUnitCompatibility\PhpUnit9;
 
-use Prophecy\PhpUnit\ProphecyTrait;
-
-// @todo Replace with a proper dependency when we stop supporting PHPUnit 8.
-if (!trait_exists(ProphecyTrait::class)) {
-  print "Drupal requires Prophecy PhpUnit when using PHPUnit 9 or greater. Please use 'composer require --dev phpspec/prophecy-phpunit:^2' to ensure that it is present.\n";
-  exit(1);
-}
-
 /**
  * Drupal's forward compatibility layer with multiple versions of PHPUnit.
  */
 trait TestCompatibilityTrait {
 
-  use ProphecyTrait;
-
 }
diff --git a/core/tests/Drupal/Tests/Component/Annotation/Plugin/Discovery/AnnotationBridgeDecoratorTest.php b/core/tests/Drupal/Tests/Component/Annotation/Plugin/Discovery/AnnotationBridgeDecoratorTest.php
index 324eab95b4bd131dbb5f22ad7902b2eef321bfff..848f499ee106b0d039b2ed537dda0622732aa17d 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/Plugin/Discovery/AnnotationBridgeDecoratorTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/Plugin/Discovery/AnnotationBridgeDecoratorTest.php
@@ -6,8 +6,8 @@
 use Drupal\Component\Annotation\Plugin\Discovery\AnnotationBridgeDecorator;
 use Drupal\Component\Plugin\Definition\PluginDefinition;
 use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
-use Drupal\Tests\PhpUnitCompatibilityTrait;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 /**
  * @coversDefaultClass \Drupal\Component\Annotation\Plugin\Discovery\AnnotationBridgeDecorator
@@ -15,7 +15,7 @@
  */
 class AnnotationBridgeDecoratorTest extends TestCase {
 
-  use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
 
   /**
    * @covers ::getDefinitions
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
index 1a2e3115d6dda0d8568bc1456108447aa8082600..a4990cc36c3f9eca5b3f08e2f72739760181ff88 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
@@ -8,8 +8,8 @@
 namespace Drupal\Tests\Component\DependencyInjection;
 
 use Drupal\Component\Utility\Crypt;
-use Drupal\Tests\PhpUnitCompatibilityTrait;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\Exception\LogicException;
@@ -25,7 +25,7 @@
  */
 class ContainerTest extends TestCase {
 
-  use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
 
   /**
    * The tested container.
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
index e53b27b6cb83d649fc2d3426580bc8df0a56b5f1..4fc0ec6a3b0050ffdbeef01844d2fb8e993917f3 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
@@ -8,8 +8,8 @@
 namespace Drupal\Tests\Component\DependencyInjection\Dumper {
 
   use Drupal\Component\Utility\Crypt;
-  use Drupal\Tests\PhpUnitCompatibilityTrait;
   use PHPUnit\Framework\TestCase;
+  use Prophecy\PhpUnit\ProphecyTrait;
   use Symfony\Bridge\PhpUnit\ExpectDeprecationTrait;
   use Symfony\Component\DependencyInjection\Definition;
   use Symfony\Component\DependencyInjection\Reference;
@@ -26,8 +26,8 @@
    */
   class OptimizedPhpArrayDumperTest extends TestCase {
 
-    use PhpUnitCompatibilityTrait;
     use ExpectDeprecationTrait;
+    use ProphecyTrait;
 
     /**
      * The container builder instance.
diff --git a/core/tests/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php b/core/tests/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php
index 361284d3d99563e36834b15756dbd0ae5dc92481..c3994a67cbc4bce3a37ba891673284f34b9019f8 100644
--- a/core/tests/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php
+++ b/core/tests/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php
@@ -5,10 +5,10 @@
 use Drupal\Component\Gettext\PoHeader;
 use Drupal\Component\Gettext\PoItem;
 use Drupal\Component\Gettext\PoStreamWriter;
-use Drupal\Tests\PhpUnitCompatibilityTrait;
 use org\bovigo\vfs\vfsStream;
 use org\bovigo\vfs\vfsStreamFile;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 /**
  * @coversDefaultClass \Drupal\Component\Gettext\PoStreamWriter
@@ -16,7 +16,7 @@
  */
 class PoStreamWriterTest extends TestCase {
 
-  use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
 
   /**
    * The PO writer object under test.
diff --git a/core/tests/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php b/core/tests/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php
index 38d47ea3456afd5f8a973b11b99aa5b42608b6c2..36b60b68a55398642a6be4fc7f57c141d8d90a2f 100644
--- a/core/tests/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php
+++ b/core/tests/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php
@@ -5,8 +5,8 @@
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
 use Drupal\Component\Plugin\Mapper\MapperInterface;
 use Drupal\Component\Plugin\PluginManagerBase;
-use Drupal\Tests\PhpUnitCompatibilityTrait;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 /**
  * @coversDefaultClass \Drupal\Component\Plugin\PluginManagerBase
@@ -14,7 +14,7 @@
  */
 class PluginManagerBaseTest extends TestCase {
 
-  use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
 
   /**
    * A callback method for mocking FactoryInterface objects.
diff --git a/core/tests/Drupal/Tests/Composer/Plugin/VendorHardening/VendorHardeningPluginTest.php b/core/tests/Drupal/Tests/Composer/Plugin/VendorHardening/VendorHardeningPluginTest.php
index 5b43d9a0344e9b820122672c0110a394ee50c16c..81b286b986dee2a1c0d921cb682ec3d58006d2b6 100644
--- a/core/tests/Drupal/Tests/Composer/Plugin/VendorHardening/VendorHardeningPluginTest.php
+++ b/core/tests/Drupal/Tests/Composer/Plugin/VendorHardening/VendorHardeningPluginTest.php
@@ -8,10 +8,10 @@
 use Composer\Package\RootPackageInterface;
 use Drupal\Composer\Plugin\VendorHardening\Config;
 use Drupal\Composer\Plugin\VendorHardening\VendorHardeningPlugin;
-use Drupal\Tests\PhpUnitCompatibilityTrait;
 use Drupal\Tests\Traits\PhpUnitWarnings;
 use org\bovigo\vfs\vfsStream;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 /**
  * @coversDefaultClass \Drupal\Composer\Plugin\VendorHardening\VendorHardeningPlugin
@@ -20,7 +20,7 @@
 class VendorHardeningPluginTest extends TestCase {
 
   use PhpUnitWarnings;
-  use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
 
   /**
    * {@inheritdoc}
diff --git a/core/tests/Drupal/Tests/UnitTestCase.php b/core/tests/Drupal/Tests/UnitTestCase.php
index 0b40c075f8e899012867688933e9acff6febcfb4..44f46e6bb825e3b28b5e892e9ce69fcafb558379 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -12,6 +12,7 @@
 use Drupal\Tests\Traits\PhpUnitWarnings;
 use Drupal\TestTools\TestVarDumper;
 use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 use Symfony\Component\VarDumper\VarDumper;
 use Symfony\Bridge\PhpUnit\ExpectDeprecationTrait;
 
@@ -27,6 +28,7 @@ abstract class UnitTestCase extends TestCase {
 
   use PhpUnitWarnings;
   use PhpUnitCompatibilityTrait;
+  use ProphecyTrait;
   use ExpectDeprecationTrait;
 
   /**