diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index d1ab0a1ec2..3260f6ea01 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -499,7 +499,7 @@ protected function setUp() {
     }
 
     // Ensure that the test is not marked as risky because of no assertions. In
-    // PHPIUnit 6 tests that only make assertions using $this->assertSession()
+    // PHPUnit 6 tests that only make assertions using $this->assertSession()
     // can be marked as risky.
     $this->addToAssertionCount(1);
   }
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
index 8be9064ac2..1b5b23f347 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
@@ -70,7 +70,12 @@ protected function setUp() {
   public function testConstruct() {
     $container_definition = $this->getMockContainerDefinition();
     $container_definition['machine_format'] = !$this->machineFormat;
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     $container = new $this->containerClass($container_definition);
   }
 
@@ -93,7 +98,12 @@ public function testGetParameter() {
    * @covers ::getAlternatives
    */
   public function testGetParameterIfNotFound() {
-    $this->setExpectedException(ParameterNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ParameterNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ParameterNotFoundException::class);
+    }
     $this->container->getParameter('parameter_that_does_not_exist');
   }
 
@@ -103,7 +113,12 @@ public function testGetParameterIfNotFound() {
    * @covers ::getParameter
    */
   public function testGetParameterIfNotFoundBecauseNull() {
-    $this->setExpectedException(ParameterNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ParameterNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ParameterNotFoundException::class);
+    }
     $this->container->getParameter(NULL);
   }
 
@@ -137,7 +152,12 @@ public function testSetParameterWithUnfrozenContainer() {
    */
   public function testSetParameterWithFrozenContainer() {
     $this->container = new $this->containerClass($this->containerDefinition);
-    $this->setExpectedException(LogicException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(LogicException::class);
+    }
+    else {
+      $this->setExpectedException(LogicException::class);
+    }
     $this->container->setParameter('some_config', 'new_value');
   }
 
@@ -242,7 +262,12 @@ public function testHasForAliasedService() {
    * @covers ::createService
    */
   public function testGetForCircularServices() {
-    $this->setExpectedException(ServiceCircularReferenceException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ServiceCircularReferenceException::class);
+    }
+    else {
+      $this->setExpectedException(ServiceCircularReferenceException::class);
+    }
     $this->container->get('circular_dependency');
   }
 
@@ -255,7 +280,12 @@ public function testGetForCircularServices() {
    * @covers ::getServiceAlternatives
    */
   public function testGetForNonExistantService() {
-    $this->setExpectedException(ServiceNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ServiceNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ServiceNotFoundException::class);
+    }
     $this->container->get('service_not_exists');
   }
 
@@ -304,7 +334,12 @@ public function testGetForParameterDependencyWithExceptionOnSecondCall() {
 
     // Reset the service.
     $this->container->set('service_parameter_not_exists', NULL);
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     $this->container->get('service_parameter_not_exists');
   }
 
@@ -316,7 +351,12 @@ public function testGetForParameterDependencyWithExceptionOnSecondCall() {
    * @covers ::resolveServicesAndParameters
    */
   public function testGetForNonExistantParameterDependencyWithException() {
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     $this->container->get('service_parameter_not_exists');
   }
 
@@ -341,7 +381,12 @@ public function testGetForNonExistantServiceDependency() {
    * @covers ::getAlternatives
    */
   public function testGetForNonExistantServiceDependencyWithException() {
-    $this->setExpectedException(ServiceNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ServiceNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ServiceNotFoundException::class);
+    }
     $this->container->get('service_dependency_not_exists');
   }
 
@@ -361,7 +406,12 @@ public function testGetForNonExistantServiceWhenUsingNull() {
    * @covers ::createService
    */
   public function testGetForNonExistantNULLService() {
-    $this->setExpectedException(ServiceNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ServiceNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ServiceNotFoundException::class);
+    }
     $this->container->get(NULL);
   }
 
@@ -387,7 +437,12 @@ public function testGetForNonExistantServiceMultipleTimes() {
    */
   public function testGetForNonExistantServiceWithExceptionOnSecondCall() {
     $this->assertNull($this->container->get('service_not_exists', ContainerInterface::NULL_ON_INVALID_REFERENCE), 'Not found service does nto throw exception.');
-    $this->setExpectedException(ServiceNotFoundException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(ServiceNotFoundException::class);
+    }
+    else {
+      $this->setExpectedException(ServiceNotFoundException::class);
+    }
     $this->container->get('service_not_exists');
   }
 
@@ -423,7 +478,12 @@ public function testGetForSyntheticService() {
    * @covers ::createService
    */
   public function testGetForSyntheticServiceWithException() {
-    $this->setExpectedException(RuntimeException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(RuntimeException::class);
+    }
+    else {
+      $this->setExpectedException(RuntimeException::class);
+    }
     $this->container->get('synthetic');
   }
 
@@ -462,7 +522,12 @@ public function testGetForInstantiationWithVariousArgumentLengths() {
    * @covers ::createService
    */
   public function testGetForWrongFactory() {
-    $this->setExpectedException(RuntimeException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(RuntimeException::class);
+    }
+    else {
+      $this->setExpectedException(RuntimeException::class);
+    }
     $this->container->get('wrong_factory');
   }
 
@@ -500,7 +565,12 @@ public function testGetForFactoryClass() {
    * @covers ::createService
    */
   public function testGetForConfiguratorWithException() {
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     $this->container->get('configurable_service_exception');
   }
 
@@ -598,7 +668,12 @@ public function testResolveServicesAndParametersForOptionalServiceDependencies()
    * @covers ::resolveServicesAndParameters
    */
   public function testResolveServicesAndParametersForInvalidArgument() {
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     $this->container->get('invalid_argument_service');
   }
 
@@ -612,7 +687,12 @@ public function testResolveServicesAndParametersForInvalidArgument() {
   public function testResolveServicesAndParametersForInvalidArguments() {
     // In case the machine-optimized format is not used, we need to simulate the
     // test failure.
-    $this->setExpectedException(InvalidArgumentException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidArgumentException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidArgumentException::class);
+    }
     if (!$this->machineFormat) {
       throw new InvalidArgumentException('Simulating the test failure.');
     }
@@ -983,31 +1063,6 @@ protected function getCollection($collection, $resolve = TRUE) {
     ];
   }
 
-  /**
-   * Compatibility layer for PHPUnit 6 to support PHPUnit 4 code.
-   *
-   * @param mixed $class
-   *   The expected exception class.
-   * @param string $message
-   *   The expected exception message.
-   * @param int $exception_code
-   *   The expected exception code.
-   */
-  public function setExpectedException($class, $message = '', $exception_code = NULL) {
-    if (method_exists($this, 'expectException')) {
-      $this->expectException($class);
-      if (!empty($message)) {
-        $this->expectExceptionMessage($message);
-      }
-      if ($exception_code !== NULL) {
-        $this->expectExceptionCode($exception_code);
-      }
-    }
-    else {
-      parent::setExpectedException($class, $message, $exception_code);
-    }
-  }
-
 }
 
 /**
diff --git a/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php b/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
index 639053623f..de24172904 100644
--- a/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
+++ b/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
@@ -50,7 +50,13 @@ public function testGetPluginClassWithValidObjectPluginDefinition() {
    * @covers ::getPluginClass
    */
   public function testGetPluginClassWithMissingClassWithArrayPluginDefinition() {
-    $this->setExpectedException(PluginException::class, 'The plugin (cherry) did not specify an instance class.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(PluginException::class);
+      $this->expectExceptionMessage('The plugin (cherry) did not specify an instance class.');
+    }
+    else {
+      $this->setExpectedException(PluginException::class, 'The plugin (cherry) did not specify an instance class.');
+    }
     DefaultFactory::getPluginClass('cherry', []);
   }
 
@@ -61,7 +67,13 @@ public function testGetPluginClassWithMissingClassWithArrayPluginDefinition() {
    */
   public function testGetPluginClassWithMissingClassWithObjectPluginDefinition() {
     $plugin_definition = $this->getMockBuilder(PluginDefinitionInterface::class)->getMock();
-    $this->setExpectedException(PluginException::class, 'The plugin (cherry) did not specify an instance class.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(PluginException::class);
+      $this->expectExceptionMessage('The plugin (cherry) did not specify an instance class.');
+    }
+    else {
+      $this->setExpectedException(PluginException::class, 'The plugin (cherry) did not specify an instance class.');
+    }
     DefaultFactory::getPluginClass('cherry', $plugin_definition);
   }
 
@@ -71,7 +83,13 @@ public function testGetPluginClassWithMissingClassWithObjectPluginDefinition() {
    * @covers ::getPluginClass
    */
   public function testGetPluginClassWithNotExistingClassWithArrayPluginDefinition() {
-    $this->setExpectedException(PluginException::class, 'Plugin (kiwifruit) instance class "\Drupal\plugin_test\Plugin\plugin_test\fruit\Kiwifruit" does not exist.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(PluginException::class);
+      $this->expectExceptionMessage('Plugin (kiwifruit) instance class "\Drupal\plugin_test\Plugin\plugin_test\fruit\Kiwifruit" does not exist.');
+    }
+    else {
+      $this->setExpectedException(PluginException::class, 'Plugin (kiwifruit) instance class "\Drupal\plugin_test\Plugin\plugin_test\fruit\Kiwifruit" does not exist.');
+    }
     DefaultFactory::getPluginClass('kiwifruit', ['class' => '\Drupal\plugin_test\Plugin\plugin_test\fruit\Kiwifruit']);
   }
 
@@ -86,7 +104,12 @@ public function testGetPluginClassWithNotExistingClassWithObjectPluginDefinition
     $plugin_definition->expects($this->atLeastOnce())
       ->method('getClass')
       ->willReturn($plugin_class);
-    $this->setExpectedException(PluginException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(PluginException::class);
+    }
+    else {
+      $this->setExpectedException(PluginException::class);
+    }
     DefaultFactory::getPluginClass('kiwifruit', $plugin_definition);
   }
 
@@ -125,7 +148,13 @@ public function testGetPluginClassWithInterfaceWithObjectPluginDefinition() {
    */
   public function testGetPluginClassWithInterfaceAndInvalidClassWithArrayPluginDefinition() {
     $plugin_class = Kale::class;
-    $this->setExpectedException(PluginException::class, 'Plugin "cherry" (Drupal\plugin_test\Plugin\plugin_test\fruit\Kale) must implement interface Drupal\plugin_test\Plugin\plugin_test\fruit\FruitInterface.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(PluginException::class);
+      $this->expectExceptionMessage('Plugin "cherry" (Drupal\plugin_test\Plugin\plugin_test\fruit\Kale) must implement interface Drupal\plugin_test\Plugin\plugin_test\fruit\FruitInterface.');
+    }
+    else {
+      $this->setExpectedException(PluginException::class, 'Plugin "cherry" (Drupal\plugin_test\Plugin\plugin_test\fruit\Kale) must implement interface Drupal\plugin_test\Plugin\plugin_test\fruit\FruitInterface.');
+    }
     DefaultFactory::getPluginClass('cherry', ['class' => $plugin_class, 'provider' => 'core'], FruitInterface::class);
   }
 
@@ -140,33 +169,13 @@ public function testGetPluginClassWithInterfaceAndInvalidClassWithObjectPluginDe
     $plugin_definition->expects($this->atLeastOnce())
       ->method('getClass')
       ->willReturn($plugin_class);
-    $this->setExpectedException(PluginException::class);
-    DefaultFactory::getPluginClass('cherry', $plugin_definition, FruitInterface::class);
-  }
-
-  /**
-   * Compatibility layer for PHPUnit 6 to support PHPUnit 4 code.
-   *
-   * @param mixed $class
-   *   The expected exception class.
-   * @param string $message
-   *   The expected exception message.
-   * @param int $exception_code
-   *   The expected exception code.
-   */
-  public function setExpectedException($class, $message = '', $exception_code = NULL) {
     if (method_exists($this, 'expectException')) {
-      $this->expectException($class);
-      if (!empty($message)) {
-        $this->expectExceptionMessage($message);
-      }
-      if ($exception_code !== NULL) {
-        $this->expectExceptionCode($exception_code);
-      }
+      $this->expectException(PluginException::class);
     }
     else {
-      parent::setExpectedException($class, $message, $exception_code);
+      $this->setExpectedException(PluginException::class);
     }
+    DefaultFactory::getPluginClass('cherry', $plugin_definition, FruitInterface::class);
   }
 
 }