diff --git a/core/modules/system/src/Tests/Module/ModuleImplementsAlterTest.php b/core/modules/system/tests/src/Kernel/Extension/ModuleImplementsAlterTest.php
similarity index 95%
rename from core/modules/system/src/Tests/Module/ModuleImplementsAlterTest.php
rename to core/modules/system/tests/src/Kernel/Extension/ModuleImplementsAlterTest.php
index 2a34c20..70c96ab 100644
--- a/core/modules/system/src/Tests/Module/ModuleImplementsAlterTest.php
+++ b/core/modules/system/tests/src/Kernel/Extension/ModuleImplementsAlterTest.php
@@ -5,9 +5,9 @@
  * Contains \Drupal\system\Tests\Module\ModuleImplementsAlterTest.
  */
 
-namespace Drupal\system\Tests\Module;
+namespace Drupal\Tests\system\Kernel\Module;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests hook_module_implements_alter().
@@ -17,6 +17,11 @@
 class ModuleImplementsAlterTest extends KernelTestBase {
 
   /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system'];
+
+  /**
    * Tests hook_module_implements_alter() adding an implementation.
    *
    * @see \Drupal\Core\Extension\ModuleHandler::buildImplementationInfo()
diff --git a/core/modules/system/src/Tests/KeyValueStore/DatabaseStorageExpirableTest.php b/core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageExpirableTest.php
similarity index 98%
rename from core/modules/system/src/Tests/KeyValueStore/DatabaseStorageExpirableTest.php
rename to core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageExpirableTest.php
index 944c9a1..4aa2463 100644
--- a/core/modules/system/src/Tests/KeyValueStore/DatabaseStorageExpirableTest.php
+++ b/core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageExpirableTest.php
@@ -5,10 +5,11 @@
  * Contains \Drupal\system\Tests\KeyValueStore\DatabaseStorageExpirableTest.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\Tests\system\Kernel\KeyValueStore;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\KeyValueStore\KeyValueFactory;
+use Drupal\KernelTests\Core\KeyValueStore\StorageTestBase;
 
 /**
  * Tests the key-value database storage.
diff --git a/core/modules/system/src/Tests/KeyValueStore/DatabaseStorageTest.php b/core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageTest.php
similarity index 77%
rename from core/modules/system/src/Tests/KeyValueStore/DatabaseStorageTest.php
rename to core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageTest.php
index dd9e44c..454c205 100644
--- a/core/modules/system/src/Tests/KeyValueStore/DatabaseStorageTest.php
+++ b/core/modules/system/tests/src/Kernel/KeyValueStore/DatabaseStorageTest.php
@@ -5,10 +5,11 @@
  * Contains \Drupal\system\Tests\KeyValueStore\DatabaseStorageTest.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\Tests\system\Kernel\KeyValueStore;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\KeyValueStore\KeyValueFactory;
+use Drupal\KernelTests\Core\KeyValueStore\StorageTestBase;
 
 /**
  * Tests the key-value database storage.
@@ -32,8 +33,8 @@ protected function setUp() {
   /**
    * {@inheritdoc}
    */
-  public function containerBuild(ContainerBuilder $container) {
-    parent::containerBuild($container);
+  public function register(ContainerBuilder $container) {
+    parent::register($container);
 
     $parameter[KeyValueFactory::DEFAULT_SETTING] = 'keyvalue.database';
     $container->setParameter('factory.keyvalue', $parameter);
diff --git a/core/modules/system/src/Tests/KeyValueStore/GarbageCollectionTest.php b/core/modules/system/tests/src/Kernel/KeyValueStore/GarbageCollectionTest.php
similarity index 95%
rename from core/modules/system/src/Tests/KeyValueStore/GarbageCollectionTest.php
rename to core/modules/system/tests/src/Kernel/KeyValueStore/GarbageCollectionTest.php
index 4a39c6f..491a7b3 100644
--- a/core/modules/system/src/Tests/KeyValueStore/GarbageCollectionTest.php
+++ b/core/modules/system/tests/src/Kernel/KeyValueStore/GarbageCollectionTest.php
@@ -5,12 +5,12 @@
  * Contains \Drupal\system\Tests\KeyValueStore\GarbageCollectionTest.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\Tests\system\Kernel\KeyValueStore;
 
 use Drupal\Component\Serialization\PhpSerialize;
 use Drupal\Core\Database\Database;
 use Drupal\Core\KeyValueStore\DatabaseStorageExpirable;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests garbage collection for the expirable key-value database storage.
diff --git a/core/modules/system/src/Tests/Menu/MenuLinkTreeTest.php b/core/modules/system/tests/src/Kernel/Menu/MenuLinkTreeTest.php
similarity index 98%
rename from core/modules/system/src/Tests/Menu/MenuLinkTreeTest.php
rename to core/modules/system/tests/src/Kernel/Menu/MenuLinkTreeTest.php
index 04e366a..de2da19 100644
--- a/core/modules/system/src/Tests/Menu/MenuLinkTreeTest.php
+++ b/core/modules/system/tests/src/Kernel/Menu/MenuLinkTreeTest.php
@@ -5,11 +5,11 @@
  * Contains \Drupal\system\Tests\Menu\MenuLinkTreeTest.
  */
 
-namespace Drupal\system\Tests\Menu;
+namespace Drupal\Tests\system\Kernel\Menu;
 
 use Drupal\Core\Menu\MenuLinkTreeElement;
 use Drupal\Core\Menu\MenuTreeParameters;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\Tests\Core\Menu\MenuLinkMock;
 
 /**
diff --git a/core/modules/system/src/Tests/Plugin/Condition/RequestPathTest.php b/core/modules/system/tests/src/Kernel/Plugin/Condition/RequestPathTest.php
similarity index 97%
rename from core/modules/system/src/Tests/Plugin/Condition/RequestPathTest.php
rename to core/modules/system/tests/src/Kernel/Plugin/Condition/RequestPathTest.php
index 7a53844..949ede5 100644
--- a/core/modules/system/src/Tests/Plugin/Condition/RequestPathTest.php
+++ b/core/modules/system/tests/src/Kernel/Plugin/Condition/RequestPathTest.php
@@ -5,10 +5,10 @@
  * Contains \Drupal\system\Tests\Plugin\Condition\RequestPathTest.
  */
 
-namespace Drupal\system\Tests\Plugin\Condition;
+namespace Drupal\Tests\system\Kernel\Plugin\Condition;
 
 use Drupal\Core\Path\CurrentPathStack;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\system\Tests\Routing\MockAliasManager;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RequestStack;
diff --git a/core/modules/system/src/Tests/Plugin/ContextPluginTest.php b/core/modules/system/tests/src/Kernel/Plugin/ContextPluginTest.php
similarity index 98%
rename from core/modules/system/src/Tests/Plugin/ContextPluginTest.php
rename to core/modules/system/tests/src/Kernel/Plugin/ContextPluginTest.php
index 4a9b73a..fdb9c76 100644
--- a/core/modules/system/src/Tests/Plugin/ContextPluginTest.php
+++ b/core/modules/system/tests/src/Kernel/Plugin/ContextPluginTest.php
@@ -5,14 +5,14 @@
  * Contains \Drupal\system\Tests\Plugin\ContextPluginTest.
  */
 
-namespace Drupal\system\Tests\Plugin;
+namespace Drupal\Tests\system\Kernel\Plugin;
 
 use Drupal\Component\Plugin\Exception\ContextException;
 use Drupal\Core\Plugin\Context\ContextDefinition;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\node\Entity\Node;
 use Drupal\node\Entity\NodeType;
 use Drupal\plugin_test\Plugin\MockBlockManager;
-use Drupal\simpletest\KernelTestBase;
 use Drupal\user\Entity\User;
 
 /**
diff --git a/core/modules/system/src/Tests/KeyValueStore/KeyValueContentEntityStorageTest.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
similarity index 99%
rename from core/modules/system/src/Tests/KeyValueStore/KeyValueContentEntityStorageTest.php
rename to core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
index cd09af9..efc6b68 100644
--- a/core/modules/system/src/Tests/KeyValueStore/KeyValueContentEntityStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
@@ -5,7 +5,7 @@
  * Contains \Drupal\system\Tests\KeyValueStore\KeyValueContentEntityStorageTest.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\KernelTests\Core\KeyValueStore;
 
 use Drupal\Core\Entity\EntityMalformedException;
 use Drupal\Core\Entity\EntityStorageException;
diff --git a/core/modules/system/src/Tests/KeyValueStore/MemoryStorageTest.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/MemoryStorageTest.php
similarity index 74%
rename from core/modules/system/src/Tests/KeyValueStore/MemoryStorageTest.php
rename to core/tests/Drupal/KernelTests/Core/KeyValueStore/MemoryStorageTest.php
index 4c6ac0c..94ee630 100644
--- a/core/modules/system/src/Tests/KeyValueStore/MemoryStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/MemoryStorageTest.php
@@ -5,10 +5,11 @@
  * Contains \Drupal\system\Tests\KeyValueStore\MemoryStorageTest.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\KernelTests\Core\KeyValueStore;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\KeyValueStore\KeyValueFactory;
+use Drupal\KernelTests\Core\KeyValueStore\StorageTestBase;
 
 /**
  * Tests the key-value memory storage.
@@ -20,8 +21,8 @@ class MemoryStorageTest extends StorageTestBase {
   /**
    * {@inheritdoc}
    */
-  public function containerBuild(ContainerBuilder $container) {
-    parent::containerBuild($container);
+  public function register(ContainerBuilder $container) {
+    parent::register($container);
 
     $container->register('keyvalue.memory', 'Drupal\Core\KeyValueStore\KeyValueMemoryFactory');
     $parameter[KeyValueFactory::DEFAULT_SETTING] = 'keyvalue.memory';
diff --git a/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
similarity index 98%
rename from core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php
rename to core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
index dd9b248..7c39ef5 100644
--- a/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
@@ -5,9 +5,9 @@
  * Contains \Drupal\system\Tests\KeyValueStore\StorageTestBase.
  */
 
-namespace Drupal\system\Tests\KeyValueStore;
+namespace Drupal\KernelTests\Core\KeyValueStore;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Base class for testing key-value storages.
diff --git a/core/modules/system/src/Tests/Lock/LockUnitTest.php b/core/tests/Drupal/KernelTests/Core/Lock/LockUnitTest.php
similarity index 96%
rename from core/modules/system/src/Tests/Lock/LockUnitTest.php
rename to core/tests/Drupal/KernelTests/Core/Lock/LockUnitTest.php
index b726add..f4c3393 100644
--- a/core/modules/system/src/Tests/Lock/LockUnitTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Lock/LockUnitTest.php
@@ -5,10 +5,10 @@
  * Contains \Drupal\system\Tests\Lock\LockUnitTest.
  */
 
-namespace Drupal\system\Tests\Lock;
+namespace Drupal\KernelTests\Core\Lock;
 
 use Drupal\Core\Lock\DatabaseLockBackend;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the Database lock backend.
diff --git a/core/modules/system/src/Tests/Menu/MenuLinkDefaultIntegrationTest.php b/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkDefaultIntegrationTest.php
similarity index 95%
rename from core/modules/system/src/Tests/Menu/MenuLinkDefaultIntegrationTest.php
rename to core/tests/Drupal/KernelTests/Core/Menu/MenuLinkDefaultIntegrationTest.php
index d96b29c..560f156 100644
--- a/core/modules/system/src/Tests/Menu/MenuLinkDefaultIntegrationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkDefaultIntegrationTest.php
@@ -5,10 +5,10 @@
  * Contains \Drupal\system\Tests\Menu\MenuLinkDefaultIntegrationTest.
  */
 
-namespace Drupal\system\Tests\Menu;
+namespace Drupal\KernelTests\Core\Menu;
 
 use Drupal\Core\Menu\MenuTreeParameters;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests integration of static menu links.
@@ -23,7 +23,6 @@ class MenuLinkDefaultIntegrationTest extends KernelTestBase {
    * @var array
    */
   public static $modules = array(
-    'system',
     'menu_test',
   );
 
diff --git a/core/modules/system/src/Tests/Menu/MenuTreeStorageTest.php b/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
similarity index 99%
rename from core/modules/system/src/Tests/Menu/MenuTreeStorageTest.php
rename to core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
index 482eea9..a82a87e 100644
--- a/core/modules/system/src/Tests/Menu/MenuTreeStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
@@ -5,12 +5,12 @@
  * Contains \Drupal\system\Tests\Menu\MenuTreeStorageTest.
  */
 
-namespace Drupal\system\Tests\Menu;
+namespace Drupal\KernelTests\Core\Menu;
 
 use Drupal\Component\Plugin\Exception\PluginException;
 use Drupal\Core\Menu\MenuTreeParameters;
 use Drupal\Core\Menu\MenuTreeStorage;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the menu tree storage.
@@ -36,13 +36,6 @@ class MenuTreeStorageTest extends KernelTestBase {
   protected $connection;
 
   /**
-   * Modules to enable.
-   *
-   * @var array
-   */
-  public static $modules = array('system');
-
-  /**
    * {@inheritdoc}
    */
   protected function setUp() {
diff --git a/core/modules/system/src/Tests/Path/AliasTest.php b/core/tests/Drupal/KernelTests/Core/Path/AliasTest.php
similarity index 99%
rename from core/modules/system/src/Tests/Path/AliasTest.php
rename to core/tests/Drupal/KernelTests/Core/Path/AliasTest.php
index 2ceb4c9..22373b3 100644
--- a/core/modules/system/src/Tests/Path/AliasTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Path/AliasTest.php
@@ -5,7 +5,7 @@
  * Contains \Drupal\system\Tests\Path\AliasTest.
  */
 
-namespace Drupal\system\Tests\Path;
+namespace Drupal\KernelTests\Core\Path;
 
 use Drupal\Core\Cache\MemoryCounterBackend;
 use Drupal\Core\Path\AliasStorage;
diff --git a/core/modules/system/src/Tests/Path/PathUnitTestBase.php b/core/tests/Drupal/KernelTests/Core/Path/PathUnitTestBase.php
similarity index 85%
rename from core/modules/system/src/Tests/Path/PathUnitTestBase.php
rename to core/tests/Drupal/KernelTests/Core/Path/PathUnitTestBase.php
index f007750..b05e13e 100644
--- a/core/modules/system/src/Tests/Path/PathUnitTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Path/PathUnitTestBase.php
@@ -5,10 +5,11 @@
  * Contains \Drupal\system\Tests\Path\PathUnitTestBase.
  */
 
-namespace Drupal\system\Tests\Path;
+namespace Drupal\KernelTests\Core\Path;
 
-use Drupal\simpletest\KernelTestBase;
 use Drupal\Core\Database\Database;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\system\Tests\Path\UrlAliasFixtures;
 
 /**
  * Base class for Path/URL alias integration tests.