diff --git a/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php b/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
index 1569411353..5d3a20b6a6 100644
--- a/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
+++ b/core/modules/block/tests/src/Unit/Plugin/DisplayVariant/BlockPageVariantTest.php
@@ -49,6 +49,7 @@ public function setUpDisplayVariant($configuration = [], $definition = []) {
     $container = new Container();
     $cache_context_manager = $this->getMockBuilder('Drupal\Core\Cache\CacheContextsManager')
       ->disableOriginalConstructor()
+      ->setMethods(['assertValidTokens'])
       ->getMock();
     $container->set('cache_contexts_manager', $cache_context_manager);
     $cache_context_manager->expects($this->any())
@@ -209,9 +210,6 @@ public function testBuild(array $blocks_config, $visible_block_count, array $exp
     $title_block_plugin = $this->getMock('Drupal\Core\Block\TitleBlockPluginInterface');
     foreach ($blocks_config as $block_id => $block_config) {
       $block = $this->getMock('Drupal\block\BlockInterface');
-      $block->expects($this->any())
-        ->method('getContexts')
-        ->willReturn([]);
       $block->expects($this->atLeastOnce())
         ->method('getPlugin')
         ->willReturn($block_config[1] ? $main_content_block_plugin : ($block_config[2] ? $messages_block_plugin : ($block_config[3] ? $title_block_plugin : $block_plugin)));
diff --git a/core/modules/content_moderation/tests/src/Kernel/EntityStateChangeValidationTest.php b/core/modules/content_moderation/tests/src/Kernel/EntityStateChangeValidationTest.php
index 2fefc0148c..d72000b868 100644
--- a/core/modules/content_moderation/tests/src/Kernel/EntityStateChangeValidationTest.php
+++ b/core/modules/content_moderation/tests/src/Kernel/EntityStateChangeValidationTest.php
@@ -217,7 +217,7 @@ public function testInvalidStateMultilingual() {
   /**
    * Tests that content without prior moderation information can be moderated.
    */
-  public function testLegacyContent() {
+  public function testExistingContentWithNoModeration() {
     $node_type = NodeType::create([
       'type' => 'example',
     ]);
@@ -251,7 +251,7 @@ public function testLegacyContent() {
   /**
    * Tests that content without prior moderation information can be translated.
    */
-  public function testLegacyMultilingualContent() {
+  public function testExistingMultilingualContentWithNoModeration() {
     // Enable French.
     ConfigurableLanguage::createFromLangcode('fr')->save();
 
diff --git a/core/modules/migrate/tests/src/Unit/MigrateTestCase.php b/core/modules/migrate/tests/src/Unit/MigrateTestCase.php
index 20d7662d29..558cecb94a 100644
--- a/core/modules/migrate/tests/src/Unit/MigrateTestCase.php
+++ b/core/modules/migrate/tests/src/Unit/MigrateTestCase.php
@@ -78,11 +78,6 @@ protected function getMigration() {
 
     $configuration = &$this->migrationConfiguration;
 
-    $migration->method('getHighWaterProperty')
-      ->willReturnCallback(function () use ($configuration) {
-        return isset($configuration['high_water_property']) ? $configuration['high_water_property'] : '';
-      });
-
     $migration->method('set')
       ->willReturnCallback(function ($argument, $value) use (&$configuration) {
         $configuration[$argument] = $value;
diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
index 95ee39fd3a..38e610c3b5 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -188,7 +188,7 @@ public function testInvalidLinkNotExistsExact() {
   /**
    * Tests legacy text asserts.
    */
-  public function testLegacyTextAsserts() {
+  public function testTextAsserts() {
     $this->drupalGet('test-encoded');
     $dangerous = 'Bad html <script>alert(123);</script>';
     $sanitized = Html::escape($dangerous);
@@ -202,7 +202,7 @@ public function testLegacyTextAsserts() {
   /**
    * Tests legacy field asserts which use xpath directly.
    */
-  public function testLegacyXpathAsserts() {
+  public function testXpathAsserts() {
     $this->drupalGet('test-field-xpath');
     $this->assertFieldsByValue($this->xpath("//h1[@class = 'page-title']"), NULL);
     $this->assertFieldsByValue($this->xpath('//table/tbody/tr[2]/td[1]'), 'one');
@@ -245,7 +245,7 @@ public function testLegacyXpathAsserts() {
   /**
    * Tests legacy field asserts using textfields.
    */
-  public function testLegacyFieldAssertsForTextfields() {
+  public function testFieldAssertsForTextfields() {
     $this->drupalGet('test-field-xpath');
 
     // *** 1. assertNoField().
@@ -387,7 +387,7 @@ public function testLegacyFieldAssertsForTextfields() {
   /**
    * Tests legacy field asserts for options field type.
    */
-  public function testLegacyFieldAssertsForOptions() {
+  public function testFieldAssertsForOptions() {
     $this->drupalGet('test-field-xpath');
 
     // Option field type.
@@ -443,7 +443,7 @@ public function testLegacyFieldAssertsForOptions() {
   /**
    * Tests legacy field asserts for button field type.
    */
-  public function testLegacyFieldAssertsForButton() {
+  public function testFieldAssertsForButton() {
     $this->drupalGet('test-field-xpath');
 
     $this->assertFieldById('edit-save', NULL);
@@ -485,7 +485,7 @@ public function testLegacyFieldAssertsForButton() {
   /**
    * Tests legacy field asserts for checkbox field type.
    */
-  public function testLegacyFieldAssertsForCheckbox() {
+  public function testFieldAssertsForCheckbox() {
     $this->drupalGet('test-field-xpath');
 
     // Part 1 - Test by name.
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index b12ba60b8a..83e43605fe 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -66,6 +66,7 @@
     createUser as drupalCreateUser;
   }
   use XdebugRequestTrait;
+  use Phpunit5FCTrait;
 
   /**
    * The database prefix of this test run.
diff --git a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
index 297125bf63..b89d351c75 100644
--- a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
+++ b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
@@ -87,7 +87,13 @@ public function testDateDiff($input1, $input2, $absolute, \DateInterval $expecte
    * @dataProvider providerTestInvalidDateDiff
    */
   public function testInvalidDateDiff($input1, $input2, $absolute) {
-    $this->setExpectedException(\BadMethodCallException::class, 'Method Drupal\Component\Datetime\DateTimePlus::diff expects parameter 1 to be a \DateTime or \Drupal\Component\Datetime\DateTimePlus object');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\BadMethodCallException::class);
+      $this->expectExceptionMessage('Method Drupal\Component\Datetime\DateTimePlus::diff expects parameter 1 to be a \DateTime or \Drupal\Component\Datetime\DateTimePlus object');
+    }
+    else {
+      $this->setExpectedException(\BadMethodCallException::class, 'Method Drupal\Component\Datetime\DateTimePlus::diff expects parameter 1 to be a \DateTime or \Drupal\Component\Datetime\DateTimePlus object');
+    }
     $interval = $input1->diff($input2, $absolute);
   }
 
@@ -104,7 +110,12 @@ public function testInvalidDateDiff($input1, $input2, $absolute) {
    * @dataProvider providerTestInvalidDateArrays
    */
   public function testInvalidDateArrays($input, $timezone, $class) {
-    $this->setExpectedException($class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException($class);
+    }
+    else {
+      $this->setExpectedException($class);
+    }
     $this->assertInstanceOf(
       '\Drupal\Component\DateTimePlus',
       DateTimePlus::createFromArray($input, $timezone)
@@ -242,7 +253,12 @@ public function testDateFormat($input, $timezone, $format, $format_date, $expect
    * @dataProvider providerTestInvalidDates
    */
   public function testInvalidDates($input, $timezone, $format, $message, $class) {
-    $this->setExpectedException($class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException($class);
+    }
+    else {
+      $this->setExpectedException($class);
+    }
     DateTimePlus::createFromFormat($format, $input, $timezone);
   }
 
@@ -800,7 +816,12 @@ public function testValidateFormat() {
 
     // Parse the same date with ['validate_format' => TRUE] and make sure we
     // get the expected exception.
-    $this->setExpectedException(\UnexpectedValueException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\UnexpectedValueException::class);
+    }
+    else {
+      $this->setExpectedException(\UnexpectedValueException::class);
+    }
     $date = DateTimePlus::createFromFormat('Y-m-d H:i:s', '11-03-31 17:44:00', 'UTC', ['validate_format' => TRUE]);
   }
 
@@ -859,7 +880,13 @@ public function testChainableNonChainable() {
    * @covers ::__call
    */
   public function testChainableNonCallable() {
-    $this->setExpectedException(\BadMethodCallException::class, 'Call to undefined method Drupal\Component\Datetime\DateTimePlus::nonexistent()');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\BadMethodCallException::class);
+      $this->expectExceptionMessage('Call to undefined method Drupal\Component\Datetime\DateTimePlus::nonexistent()');
+    }
+    else {
+      $this->setExpectedException(\BadMethodCallException::class, 'Call to undefined method Drupal\Component\Datetime\DateTimePlus::nonexistent()');
+    }
     $date = new DateTimePlus('now', 'Australia/Sydney');
     $date->setTimezone(new \DateTimeZone('America/New_York'))->nonexistent();
   }
diff --git a/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php b/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php
index 4a5fa80205..29c27b23c7 100644
--- a/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php
+++ b/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php
@@ -37,7 +37,12 @@ class TimeTest extends TestCase {
   protected function setUp() {
     parent::setUp();
 
-    $this->requestStack = $this->getMock('Symfony\Component\HttpFoundation\RequestStack');
+    if (method_exists($this, 'createMock')) {
+      $this->requestStack = $this->createMock('Symfony\Component\HttpFoundation\RequestStack');
+    }
+    else {
+      $this->requestStack = $this->getMock('Symfony\Component\HttpFoundation\RequestStack');
+    }
 
     $this->time = new Time($this->requestStack);
   }
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
index 0e6a1472cd..c2d43db027 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
@@ -983,6 +983,28 @@ protected function getCollection($collection, $resolve = TRUE) {
     ];
   }
 
+  /**
+   * Compatibility layer for PHPUnit 6 to support PHPUnit 4 code.
+   *
+   * @param mixed $class
+   * @param string $message
+   * @param int $exception_code
+   */
+  private function setExpectedException($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/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
index 3c44752748..c1b70954d1 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
@@ -545,7 +545,12 @@ public function testGetServiceDefinitionForDecoratedService() {
       $services['bar'] = $bar_definition;
 
       $this->containerBuilder->getDefinitions()->willReturn($services);
-      $this->setExpectedException(InvalidArgumentException::class);
+      if (method_exists($this, 'expectException')) {
+        $this->expectException(InvalidArgumentException::class);
+      }
+      else {
+        $this->setExpectedException(InvalidArgumentException::class);
+      }
       $this->dumper->getArray();
     }
 
@@ -562,7 +567,12 @@ public function testGetServiceDefinitionForExpression() {
       $services['bar'] = $bar_definition;
 
       $this->containerBuilder->getDefinitions()->willReturn($services);
-      $this->setExpectedException(RuntimeException::class);
+      if (method_exists($this, 'expectException')) {
+        $this->expectException(RuntimeException::class);
+      }
+      else {
+        $this->setExpectedException(RuntimeException::class);
+      }
       $this->dumper->getArray();
     }
 
@@ -579,7 +589,12 @@ public function testGetServiceDefinitionForObject() {
       $services['bar'] = $bar_definition;
 
       $this->containerBuilder->getDefinitions()->willReturn($services);
-      $this->setExpectedException(RuntimeException::class);
+      if (method_exists($this, 'expectException')) {
+        $this->expectException(RuntimeException::class);
+      }
+      else {
+        $this->setExpectedException(RuntimeException::class);
+      }
       $this->dumper->getArray();
     }
 
@@ -596,7 +611,12 @@ public function testGetServiceDefinitionForResource() {
       $services['bar'] = $bar_definition;
 
       $this->containerBuilder->getDefinitions()->willReturn($services);
-      $this->setExpectedException(RuntimeException::class);
+      if (method_exists($this, 'expectException')) {
+        $this->expectException(RuntimeException::class);
+      }
+      else {
+        $this->setExpectedException(RuntimeException::class);
+      }
       $this->dumper->getArray();
     }
 
diff --git a/core/tests/Drupal/Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php b/core/tests/Drupal/Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php
index 86134a7bdf..9ac807d744 100644
--- a/core/tests/Drupal/Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php
+++ b/core/tests/Drupal/Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php
@@ -124,7 +124,13 @@ public function testDiscoveryAlternateId() {
    * @covers ::getIdentifier
    */
   public function testDiscoveryNoIdException() {
-    $this->setExpectedException(DiscoveryException::class, 'The vfs://modules/test_1/item_1.test.yml contains no data in the identifier key \'id\'');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(DiscoveryException::class);
+      $this->expectExceptionMessage('The vfs://modules/test_1/item_1.test.yml contains no data in the identifier key \'id\'');
+    }
+    else {
+      $this->setExpectedException(DiscoveryException::class, 'The vfs://modules/test_1/item_1.test.yml contains no data in the identifier key \'id\'');
+    }
     vfsStream::setup('modules', NULL, [
       'test_1' => [
         'item_1.test.yml' => "",
@@ -144,7 +150,13 @@ public function testDiscoveryNoIdException() {
    * @covers ::findAll
    */
   public function testDiscoveryInvalidYamlException() {
-    $this->setExpectedException(DiscoveryException::class, 'The vfs://modules/test_1/item_1.test.yml contains invalid YAML');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(DiscoveryException::class);
+      $this->expectExceptionMessage('The vfs://modules/test_1/item_1.test.yml contains invalid YAML');
+    }
+    else {
+      $this->setExpectedException(DiscoveryException::class, 'The vfs://modules/test_1/item_1.test.yml contains invalid YAML');
+    }
     vfsStream::setup('modules', NULL, [
       'test_1' => [
         'item_1.test.yml' => "id: invalid\nfoo : [bar}",
diff --git a/core/tests/Drupal/Tests/Component/EventDispatcher/ContainerAwareEventDispatcherTest.php b/core/tests/Drupal/Tests/Component/EventDispatcher/ContainerAwareEventDispatcherTest.php
index ea0685a717..a750ecaf09 100644
--- a/core/tests/Drupal/Tests/Component/EventDispatcher/ContainerAwareEventDispatcherTest.php
+++ b/core/tests/Drupal/Tests/Component/EventDispatcher/ContainerAwareEventDispatcherTest.php
@@ -38,7 +38,7 @@ public function testGetListenersWithCallables()
         // When passing in callables exclusively as listeners into the event
         // dispatcher constructor, the event dispatcher must not attempt to
         // resolve any services.
-        $container = $this->getMock(ContainerInterface::class);
+        $container = $this->getMockBuilder(ContainerInterface::class)->getMock();
         $container->expects($this->never())->method($this->anything());
 
         $firstListener = new CallableClass();
@@ -73,7 +73,7 @@ public function testDispatchWithCallables()
         // When passing in callables exclusively as listeners into the event
         // dispatcher constructor, the event dispatcher must not attempt to
         // resolve any services.
-        $container = $this->getMock(ContainerInterface::class);
+        $container = $this->getMockBuilder(ContainerInterface::class)->getMock();
         $container->expects($this->never())->method($this->anything());
 
         $firstListener = new CallableClass();
diff --git a/core/tests/Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php b/core/tests/Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php
index 995f5fc851..f919598434 100644
--- a/core/tests/Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php
+++ b/core/tests/Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php
@@ -59,7 +59,13 @@ public function testGet() {
    */
   public function testGetNoPrefix() {
     FileCacheFactory::setPrefix(NULL);
-    $this->setExpectedException(\InvalidArgumentException::class, 'Required prefix configuration is missing');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\InvalidArgumentException::class);
+      $this->expectExceptionMessage('Required prefix configuration is missing');
+    }
+    else {
+      $this->setExpectedException(\InvalidArgumentException::class, 'Required prefix configuration is missing');
+    }
     FileCacheFactory::get('test_foo_settings', []);
   }
 
diff --git a/core/tests/Drupal/Tests/Component/Serialization/YamlPeclTest.php b/core/tests/Drupal/Tests/Component/Serialization/YamlPeclTest.php
index c2e0a0d888..5a71f48381 100644
--- a/core/tests/Drupal/Tests/Component/Serialization/YamlPeclTest.php
+++ b/core/tests/Drupal/Tests/Component/Serialization/YamlPeclTest.php
@@ -87,7 +87,12 @@ public function testGetFileExtension() {
    * @covers ::errorHandler
    */
   public function testError() {
-    $this->setExpectedException(InvalidDataTypeException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidDataTypeException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidDataTypeException::class);
+    }
     YamlPecl::decode('foo: [ads');
   }
 
diff --git a/core/tests/Drupal/Tests/Component/Serialization/YamlSymfonyTest.php b/core/tests/Drupal/Tests/Component/Serialization/YamlSymfonyTest.php
index 86c818c18e..d857d097a5 100644
--- a/core/tests/Drupal/Tests/Component/Serialization/YamlSymfonyTest.php
+++ b/core/tests/Drupal/Tests/Component/Serialization/YamlSymfonyTest.php
@@ -59,7 +59,12 @@ public function testGetFileExtension() {
    * @covers ::decode
    */
   public function testError() {
-    $this->setExpectedException(InvalidDataTypeException::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidDataTypeException::class);
+    }
+    else {
+      $this->setExpectedException(InvalidDataTypeException::class);
+    }
     YamlSymfony::decode('foo: [ads');
   }
 
@@ -69,7 +74,13 @@ public function testError() {
    * @covers ::encode
    */
   public function testObjectSupportDisabled() {
-    $this->setExpectedException(InvalidDataTypeException::class, 'Object support when dumping a YAML file has been disabled.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(InvalidDataTypeException::class);
+      $this->expectExceptionMessage('Object support when dumping a YAML file has been disabled.');
+    }
+    else {
+      $this->setExpectedException(InvalidDataTypeException::class, 'Object support when dumping a YAML file has been disabled.');
+    }
     $object = new \stdClass();
     $object->foo = 'bar';
     YamlSymfony::encode([$object]);
diff --git a/core/tests/Drupal/Tests/Component/Utility/ArgumentsResolverTest.php b/core/tests/Drupal/Tests/Component/Utility/ArgumentsResolverTest.php
index f15f14b85a..695edf4ba6 100644
--- a/core/tests/Drupal/Tests/Component/Utility/ArgumentsResolverTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/ArgumentsResolverTest.php
@@ -96,9 +96,16 @@ public function testGetWildcardArgument() {
    * Tests getArgument() with a Route, Request, and Account object.
    */
   public function testGetArgumentOrder() {
-    $a1 = $this->getMock('\Drupal\Tests\Component\Utility\Test1Interface');
-    $a2 = $this->getMock('\Drupal\Tests\Component\Utility\TestClass');
-    $a3 = $this->getMock('\Drupal\Tests\Component\Utility\Test2Interface');
+    if (method_exists($this, 'createMock')) {
+      $a1 = $this->createMock('\Drupal\Tests\Component\Utility\Test1Interface');
+      $a2 = $this->createMock('\Drupal\Tests\Component\Utility\TestClass');
+      $a3 = $this->createMock('\Drupal\Tests\Component\Utility\Test2Interface');
+    }
+    else {
+      $a1 = $this->getMock('\Drupal\Tests\Component\Utility\Test1Interface');
+      $a2 = $this->getMock('\Drupal\Tests\Component\Utility\TestClass');
+      $a3 = $this->getMock('\Drupal\Tests\Component\Utility\Test2Interface');
+    }
 
     $objects = [
       't1' => $a1,
@@ -123,12 +130,23 @@ public function testGetArgumentOrder() {
    * Without the typehint, the wildcard object will not be passed to the callable.
    */
   public function testGetWildcardArgumentNoTypehint() {
-    $a = $this->getMock('\Drupal\Tests\Component\Utility\Test1Interface');
+    if (method_exists($this, 'createMock')) {
+      $a = $this->createMock('\Drupal\Tests\Component\Utility\Test1Interface');
+    }
+    else {
+      $a = $this->getMock('\Drupal\Tests\Component\Utility\Test1Interface');
+    }
     $wildcards = [$a];
     $resolver = new ArgumentsResolver([], [], $wildcards);
 
     $callable = function ($route) {};
-    $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$route" argument.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\RuntimeException::class);
+      $this->expectExceptionMessage('requires a value for the "$route" argument.');
+    }
+    else {
+      $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$route" argument.');
+    }
     $resolver->getArguments($callable);
   }
 
@@ -156,7 +174,13 @@ public function testHandleNotUpcastedArgument() {
     $resolver = new ArgumentsResolver($scalars, $objects, []);
 
     $callable = function (\stdClass $foo) {};
-    $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$foo" argument.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\RuntimeException::class);
+      $this->expectExceptionMessage('requires a value for the "$foo" argument.');
+    }
+    else {
+      $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$foo" argument.');
+    }
     $resolver->getArguments($callable);
   }
 
@@ -167,7 +191,13 @@ public function testHandleNotUpcastedArgument() {
    */
   public function testHandleUnresolvedArgument($callable) {
     $resolver = new ArgumentsResolver([], [], []);
-    $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$foo" argument.');
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\RuntimeException::class);
+      $this->expectExceptionMessage('requires a value for the "$foo" argument.');
+    }
+    else {
+      $this->setExpectedException(\RuntimeException::class, 'requires a value for the "$foo" argument.');
+    }
     $resolver->getArguments($callable);
   }
 
diff --git a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
index 1860e04105..a8a8af0e6c 100644
--- a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
@@ -343,7 +343,12 @@ public function testTransformRootRelativeUrlsToAbsolute($html, $scheme_and_host,
    * @dataProvider providerTestTransformRootRelativeUrlsToAbsoluteAssertion
    */
   public function testTransformRootRelativeUrlsToAbsoluteAssertion($scheme_and_host) {
-    $this->setExpectedException(\AssertionError::class);
+    if (method_exists($this, 'expectException')) {
+      $this->expectException(\AssertionError::class);
+    }
+    else {
+      $this->setExpectedException(\AssertionError::class);
+    }
     Html::transformRootRelativeUrlsToAbsolute('', $scheme_and_host);
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Entity/Access/EntityFormDisplayAccessControlHandlerTest.php b/core/tests/Drupal/Tests/Core/Entity/Access/EntityFormDisplayAccessControlHandlerTest.php
index 1ee804d539..a92d76abb7 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Access/EntityFormDisplayAccessControlHandlerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Access/EntityFormDisplayAccessControlHandlerTest.php
@@ -164,10 +164,6 @@ protected function setUp() {
       ->willReturnMap([
         ['entity_display', $storage_access_control_handler],
       ]);
-    $entity_type_manager
-      ->expects($this->any())
-      ->method('getFieldDefinitions')
-      ->willReturn([]);
     $entity_type_manager
       ->expects($this->any())
       ->method('getDefinition')
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityListBuilderTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityListBuilderTest.php
index ad68e2df68..55928b98a6 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityListBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityListBuilderTest.php
@@ -123,9 +123,6 @@ public function testGetOperations() {
     $url = $this->getMockBuilder('\Drupal\Core\Url')
       ->disableOriginalConstructor()
       ->getMock();
-    $url->expects($this->any())
-      ->method('toArray')
-      ->will($this->returnValue([]));
     $url->expects($this->atLeastOnce())
       ->method('mergeOptions')
       ->with(['query' => ['destination' => '/foo/bar']]);
diff --git a/core/tests/Drupal/Tests/Core/Entity/KeyValueStore/KeyValueEntityStorageTest.php b/core/tests/Drupal/Tests/Core/Entity/KeyValueStore/KeyValueEntityStorageTest.php
index 4a2dac5653..846ce0a59f 100644
--- a/core/tests/Drupal/Tests/Core/Entity/KeyValueStore/KeyValueEntityStorageTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/KeyValueStore/KeyValueEntityStorageTest.php
@@ -361,7 +361,7 @@ public function testSaveConfigEntity() {
     $this->assertSame('foo', $entity->getOriginalId());
 
     $expected = ['id' => 'foo'];
-    $entity->expects($this->once())
+    $entity->expects($this->atLeastOnce())
       ->method('toArray')
       ->will($this->returnValue($expected));
 
diff --git a/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinter.php b/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinter.php
index fb1e4f4765..8021989868 100644
--- a/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinter.php
+++ b/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinter.php
@@ -15,6 +15,8 @@ class_alias('Drupal\Tests\Listeners\Legacy\HtmlOutputPrinter', 'Drupal\Tests\Lis
 else {
   /**
    * Defines a class for providing html output results for functional tests.
+   *
+   * @internal
    */
   class HtmlOutputPrinter extends ResultPrinter {
     use HtmlOutputPrinterTrait;
diff --git a/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinterTrait.php b/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinterTrait.php
index 0a9cc42dc6..9900685884 100644
--- a/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinterTrait.php
+++ b/core/tests/Drupal/Tests/Listeners/HtmlOutputPrinterTrait.php
@@ -4,6 +4,8 @@
 
 /**
  * Defines a class for providing html output results for functional tests.
+ *
+ * @internal
  */
 trait HtmlOutputPrinterTrait {
 
diff --git a/core/tests/Drupal/Tests/Listeners/Legacy/HtmlOutputPrinter.php b/core/tests/Drupal/Tests/Listeners/Legacy/HtmlOutputPrinter.php
index e5abb6ffc6..7c1f45e38f 100644
--- a/core/tests/Drupal/Tests/Listeners/Legacy/HtmlOutputPrinter.php
+++ b/core/tests/Drupal/Tests/Listeners/Legacy/HtmlOutputPrinter.php
@@ -6,6 +6,8 @@
 
 /**
  * Defines a class for providing html output results for functional tests.
+ *
+ * @internal
  */
 class HtmlOutputPrinter extends \PHPUnit_TextUI_ResultPrinter {
   use HtmlOutputPrinterTrait;
diff --git a/core/tests/Drupal/Tests/Phpunit5FCTrait.php b/core/tests/Drupal/Tests/Phpunit5FCTrait.php
index 9a123ada13..7ace0bf198 100644
--- a/core/tests/Drupal/Tests/Phpunit5FCTrait.php
+++ b/core/tests/Drupal/Tests/Phpunit5FCTrait.php
@@ -85,7 +85,42 @@ public function getMock($originalClassName, $methods = array(), array $arguments
    */
   public function createMock($originalClassName, $methods = array(), array $arguments = array(), $mockClassName = '', $callOriginalConstructor = TRUE, $callOriginalClone = TRUE, $callAutoload = TRUE, $cloneArguments = FALSE, $callOriginalMethods = FALSE, $proxyTarget = NULL) {
     if ($this->isPhpunit5()) {
-      return parent::createMock($originalClassName, $methods, $arguments, $mockClassName, $callOriginalConstructor, $callOriginalClone, $callAutoload, $cloneArguments, $callOriginalMethods, $proxyTarget);
+      $mock = $this->getMockBuilder($originalClassName)
+        ->setMethods($methods)
+        ->setConstructorArgs($arguments)
+        ->setMockClassName($mockClassName)
+        ->setProxyTarget($proxyTarget);
+      if ($callOriginalConstructor) {
+        $mock->enableOriginalConstructor();
+      }
+      else {
+        $mock->disableOriginalConstructor();
+      }
+      if ($callOriginalClone) {
+        $mock->enableOriginalClone();
+      }
+      else {
+        $mock->disableOriginalClone();
+      }
+      if ($callAutoload) {
+        $mock->enableAutoload();
+      }
+      else {
+        $mock->disableAutoload();
+      }
+      if ($cloneArguments) {
+        $mock->enableArgumentCloning();
+      }
+      else {
+        $mock->disableArgumentCloning();
+      }
+      if ($callOriginalMethods) {
+        $mock->enableProxyingToOriginalMethods();
+      }
+      else {
+        $mock->disableProxyingToOriginalMethods();
+      }
+      return $mock->getMock();
     }
     return parent::getMock($originalClassName, $methods, $arguments, $mockClassName, $callOriginalConstructor, $callOriginalClone, $callAutoload, $cloneArguments, $callOriginalMethods, $proxyTarget);
   }