diff --git a/core/tests/Drupal/Tests/Core/Cache/CacheTest.php b/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
index b836d36..a425572 100644
--- a/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
@@ -53,7 +53,8 @@ public function testValidateTags(array $tags, $expected_exception_message) {
     if ($expected_exception_message !== FALSE) {
       $this->setExpectedException('LogicException', $expected_exception_message);
     }
-    Cache::validateTags($tags);
+    // If it doesn't throw an exception, validateTags() returns NULL.
+    $this->assertNull(Cache::validateTags($tags));
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/DrupalTest.php b/core/tests/Drupal/Tests/Core/DrupalTest.php
index b281eef..fefbbbf 100644
--- a/core/tests/Drupal/Tests/Core/DrupalTest.php
+++ b/core/tests/Drupal/Tests/Core/DrupalTest.php
@@ -34,6 +34,8 @@ protected function setUp() {
 
   /**
    * Tests the get/setContainer() method.
+   *
+   * @covers ::getContainer
    */
   public function testSetContainer() {
     \Drupal::setContainer($this->container);
@@ -42,6 +44,8 @@ public function testSetContainer() {
 
   /**
    * Tests the service() method.
+   *
+   * @covers ::service
    */
   public function testService() {
     $this->setMockContainerService('test_service');
@@ -50,6 +54,8 @@ public function testService() {
 
   /**
    * Tests the currentUser() method.
+   *
+   * @covers ::currentUser
    */
   public function testCurrentUser() {
     $this->setMockContainerService('current_user');
@@ -58,6 +64,8 @@ public function testCurrentUser() {
 
   /**
    * Tests the entityManager() method.
+   *
+   * @covers ::entityManager
    */
   public function testEntityManager() {
     $this->setMockContainerService('entity.manager');
@@ -66,6 +74,8 @@ public function testEntityManager() {
 
   /**
    * Tests the database() method.
+   *
+   * @covers ::database
    */
   public function testDatabase() {
     $this->setMockContainerService('database');
@@ -74,6 +84,8 @@ public function testDatabase() {
 
   /**
    * Tests the service() method.
+   *
+   * @covers ::cache
    */
   public function testCache() {
     $this->setMockContainerService('cache.test');
@@ -82,6 +94,8 @@ public function testCache() {
 
   /**
    * Tests the keyValueExpirable() method.
+   *
+   * @covers ::keyValueExpirable
    */
   public function testKeyValueExpirable() {
     $keyvalue = $this->getMockBuilder('Drupal\Core\KeyValueStore\KeyValueExpirableFactory')
@@ -98,6 +112,8 @@ public function testKeyValueExpirable() {
 
   /**
    * Tests the lock() method.
+   *
+   * @covers ::lock
    */
   public function testLock() {
     $this->setMockContainerService('lock');
@@ -106,6 +122,8 @@ public function testLock() {
 
   /**
    * Tests the config() method.
+   *
+   * @covers ::config
    */
   public function testConfig() {
     $config = $this->getMock('Drupal\Core\Config\ConfigFactoryInterface');
@@ -120,6 +138,8 @@ public function testConfig() {
 
   /**
    * Tests the queue() method.
+   *
+   * @covers ::queue
    */
   public function testQueue() {
     $queue = $this->getMockBuilder('Drupal\Core\Queue\QueueFactory')
@@ -148,6 +168,8 @@ public function testRequestStack() {
 
   /**
    * Tests the keyValue() method.
+   *
+   * @covers ::keyValue
    */
   public function testKeyValue() {
     $keyvalue = $this->getMockBuilder('Drupal\Core\KeyValueStore\KeyValueFactory')
@@ -164,6 +186,8 @@ public function testKeyValue() {
 
   /**
    * Tests the state() method.
+   *
+   * @covers ::state
    */
   public function testState() {
     $this->setMockContainerService('state');
@@ -172,6 +196,8 @@ public function testState() {
 
   /**
    * Tests the httpClient() method.
+   *
+   * @covers ::httpClient
    */
   public function testHttpClient() {
     $this->setMockContainerService('http_client');
@@ -180,6 +206,8 @@ public function testHttpClient() {
 
   /**
    * Tests the entityQuery() method.
+   *
+   * @covers ::entityQuery
    */
   public function testEntityQuery() {
     $query = $this->getMockBuilder('Drupal\Core\Entity\Query\QueryFactory')
@@ -196,6 +224,8 @@ public function testEntityQuery() {
 
   /**
    * Tests the entityQueryAggregate() method.
+   *
+   * @covers ::entityQueryAggregate
    */
   public function testEntityQueryAggregate() {
     $query = $this->getMockBuilder('Drupal\Core\Entity\Query\QueryFactory')
@@ -212,6 +242,8 @@ public function testEntityQueryAggregate() {
 
   /**
    * Tests the flood() method.
+   *
+   * @covers ::flood
    */
   public function testFlood() {
     $this->setMockContainerService('flood');
@@ -220,6 +252,8 @@ public function testFlood() {
 
   /**
    * Tests the moduleHandler() method.
+   *
+   * @covers ::moduleHandler
    */
   public function testModuleHandler() {
     $this->setMockContainerService('module_handler');
@@ -228,6 +262,8 @@ public function testModuleHandler() {
 
   /**
    * Tests the typedData() method.
+   *
+   * @covers ::typedDataManager
    */
   public function testTypedDataManager() {
     $this->setMockContainerService('typed_data_manager');
@@ -236,6 +272,8 @@ public function testTypedDataManager() {
 
   /**
    * Tests the token() method.
+   *
+   * @covers ::token
    */
   public function testToken() {
     $this->setMockContainerService('token');
@@ -244,6 +282,8 @@ public function testToken() {
 
   /**
    * Tests the urlGenerator() method.
+   *
+   * @covers ::urlGenerator
    */
   public function testUrlGenerator() {
     $this->setMockContainerService('url_generator');
@@ -253,6 +293,7 @@ public function testUrlGenerator() {
   /**
    * Tests the _url() method.
    *
+   * @covers ::url
    * @see \Drupal\Core\Routing\UrlGeneratorInterface::generateFromRoute()
    */
   public function testUrl() {
@@ -270,6 +311,8 @@ public function testUrl() {
 
   /**
    * Tests the linkGenerator() method.
+   *
+   * @covers ::linkGenerator
    */
   public function testLinkGenerator() {
     $this->setMockContainerService('link_generator');
@@ -277,8 +320,9 @@ public function testLinkGenerator() {
   }
 
   /**
-   * Tests the _l() method.
+   * Tests the l() method.
    *
+   * @covers ::l
    * @see \Drupal\Core\Utility\LinkGeneratorInterface::generate()
    */
   public function testL() {
@@ -297,6 +341,8 @@ public function testL() {
 
   /**
    * Tests the translation() method.
+   *
+   * @covers ::translation
    */
   public function testTranslation() {
     $this->setMockContainerService('string_translation');
@@ -305,6 +351,8 @@ public function testTranslation() {
 
   /**
    * Tests the languageManager() method.
+   *
+   * @covers ::languageManager
    */
   public function testLanguageManager() {
     $this->setMockContainerService('language_manager');
@@ -313,6 +361,8 @@ public function testLanguageManager() {
 
   /**
    * Tests the csrfToken() method.
+   *
+   * @covers ::csrfToken
    */
   public function testCsrfToken() {
     $this->setMockContainerService('csrf_token');
@@ -321,6 +371,8 @@ public function testCsrfToken() {
 
   /**
    * Tests the transliteration() method.
+   *
+   * @covers ::transliteration
    */
   public function testTransliteration() {
     $this->setMockContainerService('transliteration');
@@ -329,6 +381,8 @@ public function testTransliteration() {
 
   /**
    * Tests the formBuilder() method.
+   *
+   * @covers ::formBuilder
    */
   public function testFormBuilder() {
     $this->setMockContainerService('form_builder');
@@ -337,6 +391,8 @@ public function testFormBuilder() {
 
   /**
    * Tests the menuTree() method.
+   *
+   * @covers ::menuTree
    */
   public function testMenuTree() {
     $this->setMockContainerService('menu.link_tree');
@@ -345,6 +401,8 @@ public function testMenuTree() {
 
   /**
    * Tests the pathValidator() method.
+   *
+   * @covers ::pathValidator
    */
   public function testPathValidator() {
     $this->setMockContainerService('path.validator');
@@ -353,6 +411,8 @@ public function testPathValidator() {
 
   /**
    * Tests the accessManager() method.
+   *
+   * @covers ::accessManager
    */
   public function testAccessManager() {
     $this->setMockContainerService('access_manager');
diff --git a/core/tests/Drupal/Tests/Core/Entity/BaseFieldDefinitionTest.php b/core/tests/Drupal/Tests/Core/Entity/BaseFieldDefinitionTest.php
index 2b1b3ce..8c3a0f8 100644
--- a/core/tests/Drupal/Tests/Core/Entity/BaseFieldDefinitionTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/BaseFieldDefinitionTest.php
@@ -295,7 +295,8 @@ public function testCustomStorage() {
   public function testDefaultValueCallback() {
     $definition = BaseFieldDefinition::create($this->fieldType);
     $callback = get_class($this) . '::mockDefaultValueCallback';
-    $definition->setDefaultValueCallback($callback);
+    // setDefaultValueCallback returns $this.
+    $this->assertSame($definition, $definition->setDefaultValueCallback($callback));
   }
 
   /**
@@ -306,7 +307,10 @@ public function testDefaultValueCallback() {
    */
   public function testInvalidDefaultValueCallback() {
     $definition = BaseFieldDefinition::create($this->fieldType);
-    $definition->setDefaultValueCallback([get_class($this), 'mockDefaultValueCallback']);
+    // setDefaultValueCallback returns $this.
+    $this->assertSame($definition,
+      $definition->setDefaultValueCallback([get_class($this), 'mockDefaultValueCallback'])
+    );
   }
 
   /**
@@ -316,7 +320,8 @@ public function testInvalidDefaultValueCallback() {
    */
   public function testNullDefaultValueCallback() {
     $definition = BaseFieldDefinition::create($this->fieldType);
-    $definition->setDefaultValueCallback(NULL);
+    // setDefaultValueCallback returns $this.
+    $this->assertSame($definition, $definition->setDefaultValueCallback(NULL));
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
index 222dd13..1656a3c 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
@@ -92,6 +92,7 @@ protected function setUp() {
    * @covers ::addDefaultLangcodeSchema()
    * @covers ::processBaseTable()
    * @covers ::processIdentifierSchema()
+   * @covers ::onEntityTypeCreate()
    */
   public function testGetSchemaBase() {
     $this->entityType = new ContentEntityType(array(
@@ -380,7 +381,9 @@ public function testGetSchemaBase() {
       ->method('getTableMapping')
       ->will($this->returnValue($table_mapping));
 
-    $this->storageSchema->onEntityTypeCreate($this->entityType);
+    $this->assertNull(
+      $this->storageSchema->onEntityTypeCreate($this->entityType)
+    );
   }
 
   /**
@@ -394,6 +397,7 @@ public function testGetSchemaBase() {
    * @covers ::getEntityIndexName()
    * @covers ::processRevisionTable()
    * @covers ::processIdentifierSchema()
+   * @covers ::onEntityTypeCreate()
    */
   public function testGetSchemaRevisionable() {
     $this->entityType = new ContentEntityType(array(
@@ -568,7 +572,9 @@ public function testGetSchemaTranslatable() {
       ->method('getTableMapping')
       ->will($this->returnValue($table_mapping));
 
-    $this->storageSchema->onEntityTypeCreate($this->entityType);
+    $this->assertNull(
+      $this->storageSchema->onEntityTypeCreate($this->entityType)
+    );
   }
 
   /**
@@ -898,7 +904,9 @@ public function testDedicatedTableSchema() {
       ->method('getTableMapping')
       ->will($this->returnValue($table_mapping));
 
-    $this->storageSchema->onFieldStorageDefinitionCreate($field_storage);
+    $this->assertNull(
+      $this->storageSchema->onFieldStorageDefinitionCreate($field_storage)
+    );
   }
 
   /**
@@ -1043,7 +1051,9 @@ public function testDedicatedTableSchemaForEntityWithStringIdentifier() {
       ->method('getTableMapping')
       ->will($this->returnValue($table_mapping));
 
-    $this->storageSchema->onFieldStorageDefinitionCreate($field_storage);
+    $this->assertNull(
+      $this->storageSchema->onFieldStorageDefinitionCreate($field_storage)
+    );
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
index a4750ca..6ec541b 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
@@ -218,7 +218,7 @@ public function testCreateInstanceWithJustValidInterfaces() {
     $plugin_manager = new TestPluginManager($this->namespaces, $this->expectedDefinitions, NULL, NULL, '\Drupal\plugin_test\Plugin\plugin_test\fruit\FruitInterface');
 
     foreach ($this->expectedDefinitions as $plugin_id => $definition) {
-      $plugin_manager->createInstance($plugin_id);
+      $this->assertNotNull($plugin_manager->createInstance($plugin_id));
     }
   }
 
@@ -276,7 +276,7 @@ public function testGetDefinitionsWithoutRequiredInterface() {
     $this->expectedDefinitions['banana']['provider'] = 'plugin_test';
 
     $plugin_manager = new TestPluginManager($this->namespaces, $this->expectedDefinitions, $module_handler, NULL);
-    $plugin_manager->getDefinitions();
+    $this->assertInternalType('array', $plugin_manager->getDefinitions());
   }
 
 }
diff --git a/core/tests/Drupal/Tests/Core/Routing/AccessAwareRouterTest.php b/core/tests/Drupal/Tests/Core/Routing/AccessAwareRouterTest.php
index 77b73d7..17409b4 100644
--- a/core/tests/Drupal/Tests/Core/Routing/AccessAwareRouterTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/AccessAwareRouterTest.php
@@ -14,7 +14,7 @@
 use Symfony\Component\Routing\Route;
 
 /**
- * @coversDefaultClass \Drupal\Core\Routing\Router
+ * @coversDefaultClass \Drupal\Core\Routing\AccessAwareRouter
  * @group Routing
  */
 class AccessAwareRouterTest extends UnitTestCase {
diff --git a/core/tests/Drupal/Tests/Core/StackMiddleware/ReverseProxyMiddlewareTest.php b/core/tests/Drupal/Tests/Core/StackMiddleware/ReverseProxyMiddlewareTest.php
index 231f833..f92109b 100644
--- a/core/tests/Drupal/Tests/Core/StackMiddleware/ReverseProxyMiddlewareTest.php
+++ b/core/tests/Drupal/Tests/Core/StackMiddleware/ReverseProxyMiddlewareTest.php
@@ -51,7 +51,7 @@ public function testNoProxy() {
   /**
    * Tests that subscriber sets trusted headers when reverse proxy is set.
    *
-   * @dataProvider testReverseProxyEnabledProvider
+   * @dataProvider reverseProxyEnabledProvider
    */
   public function testReverseProxyEnabled($provided_settings) {
       // Enable reverse proxy and add test values.
@@ -62,7 +62,7 @@ public function testReverseProxyEnabled($provided_settings) {
   /**
    * Data provider for testReverseProxyEnabled.
    */
-  public function testReverseProxyEnabledProvider() {
+  public function reverseProxyEnabledProvider() {
     return array(
       array(
         array(