diff --git a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitGdTest.php b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitGdTest.php
index 6f4075d..b139c88 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitGdTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitGdTest.php
@@ -215,7 +215,7 @@ function testManipulations() {
       );
     }
 
-    $manager = new ImageToolkitManager($this->container->get('container.namespaces'));
+    $manager = new ImageToolkitManager($this->container->get('container.namespaces'), $this->container->get('cache.cache'), $this->container->get('language_manager'), $this->container->get('module_handler'));
     foreach ($files as $file) {
       foreach ($operations as $op => $values) {
         // Load up a fresh image.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTest.php b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTest.php
index d0d64a3..4314d72 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTest.php
@@ -26,7 +26,7 @@ public static function getInfo() {
    * available toolkits.
    */
   function testGetAvailableToolkits() {
-    $manager = new ImageToolkitManager($this->container->get('container.namespaces'));
+    $manager = new ImageToolkitManager($this->container->get('container.namespaces'), $this->container->get('cache.cache'), $this->container->get('language_manager'), $this->container->get('module_handler'));
     $toolkits = $manager->getAvailableToolkits();
     $this->assertTrue(isset($toolkits['test']), 'The working toolkit was returned.');
     $this->assertFalse(isset($toolkits['broken']), 'The toolkit marked unavailable was not returned');
diff --git a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
index 260b2da..c191cad 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
@@ -31,7 +31,7 @@ function setUp() {
     parent::setUp();
 
     // Use the image_test.module's test toolkit.
-    $manager = new ImageToolkitManager($this->container->get('container.namespaces'));
+    $manager = new ImageToolkitManager($this->container->get('container.namespaces'), $this->container->get('cache.cache'), $this->container->get('language_manager'), $this->container->get('module_handler'));
     $this->toolkit = $manager->createInstance('test');
 
     // Pick a file for testing.
diff --git a/core/modules/system/tests/modules/condition_test/lib/Drupal/condition_test/FormController.php b/core/modules/system/tests/modules/condition_test/lib/Drupal/condition_test/FormController.php
index b1012c2..3e42efc 100644
--- a/core/modules/system/tests/modules/condition_test/lib/Drupal/condition_test/FormController.php
+++ b/core/modules/system/tests/modules/condition_test/lib/Drupal/condition_test/FormController.php
@@ -33,7 +33,7 @@ public function getFormID() {
    * Constructs a \Drupal\condition_test\FormController object.
    */
   public function __construct() {
-    $manager = new ConditionManager(\Drupal::service('container.namespaces'));
+    $manager = new ConditionManager(\Drupal::service('container.namespaces'), \Drupal::cache('cache'), \Drupal::service('language_manager'), \Drupal::moduleHandler());
     $this->condition = $manager->createInstance('node_type');
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
index b771fa1..6397640 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
@@ -51,7 +51,7 @@ public static function getInfo() {
     );
   }
 
-  function setUp() {
+  public function setUp() {
     $this->expectedDefinitions = array(
       'apple' => array(
         'id' => 'apple',
@@ -76,15 +76,16 @@ function setUp() {
   /**
    * Tests the plugin manager with no cache and altering.
    */
-  function testDefaultPluginManager() {
+  public function testDefaultPluginManager() {
     $plugin_manager = new TestPluginManager($this->namespaces, $this->expectedDefinitions);
     $this->assertEquals($this->expectedDefinitions, $plugin_manager->getDefinitions());
+    $this->assertEquals($this->expectedDefinitions['banana'], $plugin_manager->getDefinition('banana'));
   }
 
   /**
    * Tests the plugin manager with no cache and altering.
    */
-  function testDefaultPluginManagerWithAlter() {
+  public function testDefaultPluginManagerWithAlter() {
     $module_handler = $this->getMock('Drupal\Core\Extension\ModuleHandler');
 
     // Configure the stub.
@@ -97,12 +98,13 @@ function testDefaultPluginManagerWithAlter() {
     $plugin_manager->setAlterHook($module_handler, $alter_hook_name);
 
     $this->assertEquals($this->expectedDefinitions, $plugin_manager->getDefinitions());
+    $this->assertEquals($this->expectedDefinitions['banana'], $plugin_manager->getDefinition('banana'));
   }
 
   /**
    * Tests the plugin manager with caching and altering.
    */
-  function testDefaultPluginManagerWithEmptyCache() {
+  public function testDefaultPluginManagerWithEmptyCache() {
     $cid = $this->randomName();
     $cache_backend = $this->getMockBuilder('Drupal\Core\Cache\MemoryBackend')
       ->disableOriginalConstructor()
@@ -128,12 +130,13 @@ function testDefaultPluginManagerWithEmptyCache() {
     $plugin_manager->setCache($cache_backend, $language_manager, $cid);
 
     $this->assertEquals($this->expectedDefinitions, $plugin_manager->getDefinitions());
+    $this->assertEquals($this->expectedDefinitions['banana'], $plugin_manager->getDefinition('banana'));
   }
 
   /**
    * Tests the plugin manager with caching and altering.
    */
-  function testDefaultPluginManagerWithFilledCache() {
+  public function testDefaultPluginManagerWithFilledCache() {
     $cid = $this->randomName();
     $cache_backend = $this->getMockBuilder('Drupal\Core\Cache\MemoryBackend')
       ->disableOriginalConstructor()
diff --git a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
index 0f97c00..cc23350 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
@@ -42,11 +42,11 @@ public function __construct(\Traversable $namespaces, $definitions) {
    * @param \Drupal\Core\Extension\ModuleHandler $module_handler
    *   The module handler to invoke the alter hook with.
    * @param string $alter_hook
-   *   (optional) Name of the alter hook. Defaults to $owner_$type if not given.
+   *   Name of the alter hook. Defaults to $owner_$type if not given.
    */
-  public function setAlterHook(ModuleHandlerInterface $module_handler, $alter_hook = NULL) {
+  public function setAlterHook(ModuleHandlerInterface $module_handler, $alter_hook) {
     $this->moduleHandler = $module_handler;
-    $this->alterHook = $alter_hook ? $alter_hook : strtolower($this->subdir);
+    $this->alterHook = $alter_hook;
   }
 
 }
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index 36cd94e..08d8871 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -1,7 +1,5 @@
 <?php
 
-use Drupal\Component\Utility\String;
-
 // Register the namespaces we'll need to autoload from.
 $loader = require __DIR__ . "/../vendor/autoload.php";
 $loader->add('Drupal\\', __DIR__);