diff --git a/core/modules/aggregator/src/Tests/AggregatorTitleTest.php b/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
similarity index 87%
rename from core/modules/aggregator/src/Tests/AggregatorTitleTest.php
rename to core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
index d599d9a..376bce6 100644
--- a/core/modules/aggregator/src/Tests/AggregatorTitleTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\aggregator\Tests\AggregatorTitleTest.
+ * Contains \Drupal\Tests\aggregator\Kernel\AggregatorTitleTest.
  */
 
-namespace Drupal\aggregator\Tests;
+namespace Drupal\Tests\aggregator\Kernel;
 
 use Drupal\aggregator\Entity\Feed;
 use Drupal\aggregator\Entity\Item;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 
 /**
@@ -24,7 +24,7 @@ class AggregatorTitleTest extends KernelTestBase {
    *
    * @var array
    */
-  public static $modules = ['file', 'field', 'options', 'aggregator'];
+  public static $modules = ['file', 'field', 'options', 'aggregator', 'system'];
 
   /**
    * The field name that is tested.
@@ -43,6 +43,8 @@ protected function setUp() {
     $this->installEntitySchema('aggregator_feed');
     $this->installEntitySchema('aggregator_item');
 
+    \Drupal::service('router.builder')->rebuild();
+
     $this->fieldName = 'title';
   }
 
@@ -74,7 +76,7 @@ public function testStringFormatter() {
 
     $build = $aggregator_feed->{$this->fieldName}->view(['type' => 'aggregator_title', 'settings' => ['display_as_link' => FALSE]]);
     $result = $this->render($build);
-    $this->assertTrue(strpos($result, 'testing title') === 0);
+    $this->assertTrue(strpos($result, 'testing title') !== FALSE);
     $this->assertTrue(strpos($result, $aggregator_feed->getUrl()) === FALSE);
 
     // Verify aggregator item title with and without links.
@@ -86,7 +88,7 @@ public function testStringFormatter() {
 
     $build = $aggregator_item->{$this->fieldName}->view(['type' => 'aggregator_title', 'settings' => ['display_as_link' => FALSE]]);
     $result = $this->render($build);
-    $this->assertTrue(strpos($result, 'test title') === 0);
+    $this->assertTrue(strpos($result, 'test title') !== FALSE);
     $this->assertTrue(strpos($result, $aggregator_item->getLink()) === FALSE);
   }
 
diff --git a/core/modules/aggregator/src/Tests/FeedValidationTest.php b/core/modules/aggregator/tests/src/Kernel/FeedValidationTest.php
similarity index 87%
rename from core/modules/aggregator/src/Tests/FeedValidationTest.php
rename to core/modules/aggregator/tests/src/Kernel/FeedValidationTest.php
index 2c127d0..fd68d1b 100644
--- a/core/modules/aggregator/src/Tests/FeedValidationTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/FeedValidationTest.php
@@ -2,20 +2,20 @@
 
 /**
  * @file
- * Contains \Drupal\aggregator\Tests\FeedValidationTest.
+ * Contains \Drupal\Tests\aggregator\Kernel\FeedValidationTest.
  */
 
-namespace Drupal\aggregator\Tests;
+namespace Drupal\Tests\aggregator\Kernel;
 
 use Drupal\aggregator\Entity\Feed;
-use Drupal\system\Tests\Entity\EntityUnitTestBase;
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
 
 /**
  * Tests feed validation constraints.
  *
  * @group aggregator
  */
-class FeedValidationTest extends EntityUnitTestBase {
+class FeedValidationTest extends EntityKernelTestBase {
 
   /**
    * Modules to install.
diff --git a/core/modules/aggregator/src/Tests/ItemWithoutFeedTest.php b/core/modules/aggregator/tests/src/Kernel/ItemWithoutFeedTest.php
similarity index 88%
rename from core/modules/aggregator/src/Tests/ItemWithoutFeedTest.php
rename to core/modules/aggregator/tests/src/Kernel/ItemWithoutFeedTest.php
index a6586b9..2e5bca4 100644
--- a/core/modules/aggregator/src/Tests/ItemWithoutFeedTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/ItemWithoutFeedTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\aggregator\Tests\ItemWithoutFeedTest.
+ * Contains \Drupal\Tests\aggregator\Unit\ItemWithoutFeedTest.
  */
 
-namespace Drupal\aggregator\Tests;
+namespace Drupal\Tests\aggregator\Kernel;
 
 use Drupal\aggregator\Entity\Item;
 use Drupal\KernelTests\KernelTestBase;
diff --git a/core/modules/block/src/Tests/BlockConfigSchemaTest.php b/core/modules/block/tests/src/Kernel/BlockConfigSchemaTest.php
similarity index 93%
rename from core/modules/block/src/Tests/BlockConfigSchemaTest.php
rename to core/modules/block/tests/src/Kernel/BlockConfigSchemaTest.php
index 9d7bcfe..88b8e81 100644
--- a/core/modules/block/src/Tests/BlockConfigSchemaTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockConfigSchemaTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\block\Tests\BlockConfigSchemaTest.
+ * Contains \Drupal\Tests\block\Kernel\BlockConfigSchemaTest.
  */
 
-namespace Drupal\block\Tests;
+namespace Drupal\Tests\block\Kernel;
 
 use Drupal\block\Entity\Block;
 use Drupal\config\Tests\SchemaCheckTestTrait;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the block config schema.
diff --git a/core/modules/block/src/Tests/BlockInterfaceTest.php b/core/modules/block/tests/src/Kernel/BlockInterfaceTest.php
similarity index 96%
rename from core/modules/block/src/Tests/BlockInterfaceTest.php
rename to core/modules/block/tests/src/Kernel/BlockInterfaceTest.php
index 5af8ec0..36dedcf 100644
--- a/core/modules/block/src/Tests/BlockInterfaceTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockInterfaceTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\block\Tests\BlockInterfaceTest.
+ * Contains \Drupal\Tests\block\Kernel\BlockInterfaceTest.
  */
 
-namespace Drupal\block\Tests;
+namespace Drupal\Tests\block\Kernel;
 
 use Drupal\Core\Form\FormState;
-use Drupal\simpletest\KernelTestBase;
 use Drupal\block\BlockInterface;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests that the block plugin can work properly without a supporting entity.
@@ -17,6 +17,7 @@
  * @group block
  */
 class BlockInterfaceTest extends KernelTestBase {
+
   public static $modules = array('system', 'block', 'block_test', 'user');
 
   /**
diff --git a/core/modules/block/src/Tests/BlockStorageUnitTest.php b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
similarity index 95%
rename from core/modules/block/src/Tests/BlockStorageUnitTest.php
rename to core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
index db892cb..3361665 100644
--- a/core/modules/block/src/Tests/BlockStorageUnitTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\block\Tests\BlockStorageUnitTest.
+ * Contains \Drupal\Tests\block\Kernel\BlockStorageUnitTest.
  */
 
-namespace Drupal\block\Tests;
+namespace Drupal\Tests\block\Kernel;
 
 use Drupal\Core\Config\Entity\ConfigEntityStorage;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\block_test\Plugin\Block\TestHtmlBlock;
 use Drupal\Component\Plugin\Exception\PluginException;
 use Drupal\block\Entity\Block;
@@ -26,7 +26,7 @@ class BlockStorageUnitTest extends KernelTestBase {
    *
    * @var array
    */
-  public static $modules = array('block', 'block_test');
+  public static $modules = array('block', 'block_test', 'system');
 
   /**
    * The block storage.
diff --git a/core/modules/block/src/Tests/BlockViewBuilderTest.php b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
similarity index 98%
rename from core/modules/block/src/Tests/BlockViewBuilderTest.php
rename to core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
index fdfa089..be70015 100644
--- a/core/modules/block/src/Tests/BlockViewBuilderTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\block\Tests\BlockViewBuilderTest.
+ * Contains \Drupal\Tests\block\Kernel\BlockViewBuilderTest.
  */
 
-namespace Drupal\block\Tests;
+namespace Drupal\Tests\block\Kernel;
 
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Language\LanguageInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\block\Entity\Block;
 
 /**
diff --git a/core/modules/book/src/Tests/BookUninstallTest.php b/core/modules/book/tests/src/Kernel/BookUninstallTest.php
similarity index 96%
rename from core/modules/book/src/Tests/BookUninstallTest.php
rename to core/modules/book/tests/src/Kernel/BookUninstallTest.php
index 0a18fb1..5cb7327 100644
--- a/core/modules/book/src/Tests/BookUninstallTest.php
+++ b/core/modules/book/tests/src/Kernel/BookUninstallTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\book\Tests\BookUninstallTest.
+ * Contains \Drupal\Tests\book\Kernel\BookUninstallTest.
  */
 
-namespace Drupal\book\Tests;
+namespace Drupal\Tests\book\Kernel;
 
 use Drupal\node\Entity\Node;
 use Drupal\node\Entity\NodeType;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests that the Book module cannot be uninstalled if books exist.
diff --git a/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php b/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
similarity index 97%
rename from core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php
rename to core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
index 0b132a9..0328c14 100644
--- a/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php
+++ b/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
@@ -1,12 +1,12 @@
 <?php
 /**
  * @file
- * Contains \Drupal\breakpoint\Tests\BreakpointDiscoveryTest.
+ * Contains \Drupal\Tests\breakpoint\Kernel\BreakpointDiscoveryTest.
  */
 
-namespace Drupal\breakpoint\Tests;
+namespace Drupal\Tests\breakpoint\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests discovery of breakpoints provided by themes and modules.
diff --git a/core/modules/ckeditor/src/Tests/CKEditorPluginManagerTest.php b/core/modules/ckeditor/tests/modules/src/Kernel/CKEditorPluginManagerTest.php
similarity index 98%
rename from core/modules/ckeditor/src/Tests/CKEditorPluginManagerTest.php
rename to core/modules/ckeditor/tests/modules/src/Kernel/CKEditorPluginManagerTest.php
index 002de2b..ab11491 100644
--- a/core/modules/ckeditor/src/Tests/CKEditorPluginManagerTest.php
+++ b/core/modules/ckeditor/tests/modules/src/Kernel/CKEditorPluginManagerTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\ckeditor\Tests\CKEditorPluginManagerTest.
+ * Contains \Drupal\Tests\ckeditor\Kernel\CKEditorPluginManagerTest.
  */
 
-namespace Drupal\ckeditor\Tests;
+namespace Drupal\Tests\ckeditor\Kernel;
 
 use Drupal\editor\Entity\Editor;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\filter\Entity\FilterFormat;
 
 /**
diff --git a/core/modules/ckeditor/src/Tests/CKEditorTest.php b/core/modules/ckeditor/tests/modules/src/Kernel/CKEditorTest.php
similarity index 99%
rename from core/modules/ckeditor/src/Tests/CKEditorTest.php
rename to core/modules/ckeditor/tests/modules/src/Kernel/CKEditorTest.php
index 5ac3a04..b421525 100644
--- a/core/modules/ckeditor/src/Tests/CKEditorTest.php
+++ b/core/modules/ckeditor/tests/modules/src/Kernel/CKEditorTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\ckeditor\Tests\CKEditorTest.
+ * Contains \Drupal\Tests\ckeditor\Kernel\CKEditorTest.
  */
 
-namespace Drupal\ckeditor\Tests;
+namespace Drupal\Tests\ckeditor\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\editor\Entity\Editor;
 use Drupal\filter\Entity\FilterFormat;
diff --git a/core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php b/core/modules/comment/tests/src/Kernel/CommentStringIdEntitiesTest.php
similarity index 91%
rename from core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php
rename to core/modules/comment/tests/src/Kernel/CommentStringIdEntitiesTest.php
index ef7f48d..ae4627f 100644
--- a/core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php
+++ b/core/modules/comment/tests/src/Kernel/CommentStringIdEntitiesTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\comment\Tests\CommentStringIdEntitiesTest.
+ * Contains \Drupal\Tests\comment\Kernel\CommentStringIdEntitiesTest.
  */
 
-namespace Drupal\comment\Tests;
+namespace Drupal\Tests\comment\Kernel;
 
 use Drupal\comment\Entity\CommentType;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
diff --git a/core/modules/config/src/Tests/CacheabilityMetadataConfigOverrideTest.php b/core/modules/config/tests/src/Kernel/CacheabilityMetadataConfigOverrideTest.php
similarity index 95%
rename from core/modules/config/src/Tests/CacheabilityMetadataConfigOverrideTest.php
rename to core/modules/config/tests/src/Kernel/CacheabilityMetadataConfigOverrideTest.php
index e559d80..a6f5de9 100644
--- a/core/modules/config/src/Tests/CacheabilityMetadataConfigOverrideTest.php
+++ b/core/modules/config/tests/src/Kernel/CacheabilityMetadataConfigOverrideTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\CacheabilityMetadataConfigOverrideTest.
+ * Contains \Drupal\Tests\config\Kernel\CacheabilityMetadataConfigOverrideTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\config_override_test\Cache\PirateDayCacheContext;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests if configuration overrides correctly affect cacheability metadata.
diff --git a/core/modules/config/src/Tests/ConfigCRUDTest.php b/core/modules/config/tests/src/Kernel/ConfigCRUDTest.php
similarity index 98%
rename from core/modules/config/src/Tests/ConfigCRUDTest.php
rename to core/modules/config/tests/src/Kernel/ConfigCRUDTest.php
index 3d61c9e..c763ade 100644
--- a/core/modules/config/src/Tests/ConfigCRUDTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigCRUDTest.php
@@ -2,19 +2,19 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigCRUDTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigCRUDTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\ConfigNameException;
 use Drupal\Core\Config\ConfigValueException;
 use Drupal\Core\Config\InstallStorage;
-use Drupal\simpletest\KernelTestBase;
 use Drupal\Core\Config\DatabaseStorage;
 use Drupal\Core\Config\UnsupportedDataTypeConfigException;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests CRUD operations on configuration objects.
diff --git a/core/modules/config/src/Tests/ConfigDiffTest.php b/core/modules/config/tests/src/Kernel/ConfigDiffTest.php
similarity index 98%
rename from core/modules/config/src/Tests/ConfigDiffTest.php
rename to core/modules/config/tests/src/Kernel/ConfigDiffTest.php
index 1f32b27..32f40f8 100644
--- a/core/modules/config/src/Tests/ConfigDiffTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigDiffTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigDiffTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigDiffTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Calculating the difference between two sets of configuration.
diff --git a/core/modules/config/src/Tests/ConfigEntityNormalizeTest.php b/core/modules/config/tests/src/Kernel/ConfigEntityNormalizeTest.php
similarity index 89%
rename from core/modules/config/src/Tests/ConfigEntityNormalizeTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEntityNormalizeTest.php
index 7e0acef..639cf6d 100644
--- a/core/modules/config/src/Tests/ConfigEntityNormalizeTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEntityNormalizeTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEntityNormalizeTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEntityNormalizeTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the listing of configuration entities.
diff --git a/core/modules/config/src/Tests/ConfigEntityStaticCacheTest.php b/core/modules/config/tests/src/Kernel/ConfigEntityStaticCacheTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigEntityStaticCacheTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEntityStaticCacheTest.php
index e36331c..35e68f9 100644
--- a/core/modules/config/src/Tests/ConfigEntityStaticCacheTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEntityStaticCacheTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEntityStaticCacheTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEntityStaticCacheTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\config_entity_static_cache_test\ConfigOverrider;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the entity static cache when used by config entities.
diff --git a/core/modules/config/src/Tests/ConfigEntityStatusTest.php b/core/modules/config/tests/src/Kernel/ConfigEntityStatusTest.php
similarity index 87%
rename from core/modules/config/src/Tests/ConfigEntityStatusTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEntityStatusTest.php
index caad767..695c914 100644
--- a/core/modules/config/src/Tests/ConfigEntityStatusTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEntityStatusTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEntityStatusTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEntityStatusTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests configuration entity status functionality.
diff --git a/core/modules/config/src/Tests/ConfigEntityStorageTest.php b/core/modules/config/tests/src/Kernel/ConfigEntityStorageTest.php
similarity index 91%
rename from core/modules/config/src/Tests/ConfigEntityStorageTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEntityStorageTest.php
index 0eb1ab6..14c3ddb 100644
--- a/core/modules/config/src/Tests/ConfigEntityStorageTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEntityStorageTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEntityStorageTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEntityStorageTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
 use Drupal\Core\Config\ConfigDuplicateUUIDException;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests sync and importing config entities with IDs and UUIDs that match
diff --git a/core/modules/config/src/Tests/ConfigEntityUnitTest.php b/core/modules/config/tests/src/Kernel/ConfigEntityUnitTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigEntityUnitTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEntityUnitTest.php
index dd6a586..3698691 100644
--- a/core/modules/config/src/Tests/ConfigEntityUnitTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEntityUnitTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEntityUnitTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEntityUnitTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Unit tests for configuration entity base methods.
diff --git a/core/modules/config/src/Tests/ConfigEventsTest.php b/core/modules/config/tests/src/Kernel/ConfigEventsTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigEventsTest.php
rename to core/modules/config/tests/src/Kernel/ConfigEventsTest.php
index 431552e..84830b5 100644
--- a/core/modules/config/src/Tests/ConfigEventsTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigEventsTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigEventsTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigEventsTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\Config;
 use Drupal\Core\Config\ConfigEvents;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests events fired on configuration objects.
diff --git a/core/modules/config/src/Tests/ConfigFileContentTest.php b/core/modules/config/tests/src/Kernel/ConfigFileContentTest.php
similarity index 93%
rename from core/modules/config/src/Tests/ConfigFileContentTest.php
rename to core/modules/config/tests/src/Kernel/ConfigFileContentTest.php
index 186458f..b1ac896 100644
--- a/core/modules/config/src/Tests/ConfigFileContentTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigFileContentTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigFileContentTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigFileContentTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\FileStorage;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests reading and writing of configuration files.
@@ -121,16 +121,16 @@ function testReadWriteConfig() {
     $this->assertNull($config->get('i.dont.exist'), 'Non-existent nested value returned NULL.');
 
     // Read false value.
-    $this->assertEqual($config->get($false_key), '0', "Boolean FALSE value returned the string '0'.");
+    $this->assertSame($config->get($false_key), FALSE, "Boolean FALSE value returned the FALSE.");
 
     // Read true value.
-    $this->assertEqual($config->get($true_key), '1', "Boolean TRUE value returned the string '1'.");
+    $this->assertSame($config->get($true_key), TRUE, "Boolean TRUE value returned the TRUE.");
 
     // Read null value.
     $this->assertIdentical($config->get('null'), NULL);
 
     // Read false that had been nested in an array value.
-    $this->assertEqual($config->get($casting_array_false_value_key), '0', "Nested boolean FALSE value returned the string '0'.");
+    $this->assertSame($config->get($casting_array_false_value_key), FALSE, "Nested boolean FALSE value returned FALSE.");
 
     // Unset a top level value.
     $config->clear($key);
@@ -210,7 +210,7 @@ function testSerialization() {
     );
 
     // Encode and write, and reload and decode the configuration data.
-    $filestorage = new FileStorage($this->configDirectories[CONFIG_SYNC_DIRECTORY]);
+    $filestorage = new FileStorage(config_get_config_directory(CONFIG_SYNC_DIRECTORY));
     $filestorage->write($name, $config_data);
     $config_parsed = $filestorage->read($name);
 
diff --git a/core/modules/config/src/Tests/ConfigImportRecreateTest.php b/core/modules/config/tests/src/Kernel/ConfigImportRecreateTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigImportRecreateTest.php
rename to core/modules/config/tests/src/Kernel/ConfigImportRecreateTest.php
index 163389f..51b22cd 100644
--- a/core/modules/config/src/Tests/ConfigImportRecreateTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigImportRecreateTest.php
@@ -2,16 +2,16 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigImportRecreateTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigImportRecreateTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\StorageComparer;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\node\Entity\NodeType;
-use Drupal\simpletest\KernelTestBase;
 
 /**
  * Tests importing recreated configuration entities.
diff --git a/core/modules/config/src/Tests/ConfigImportRenameValidationTest.php b/core/modules/config/tests/src/Kernel/ConfigImportRenameValidationTest.php
similarity index 97%
rename from core/modules/config/src/Tests/ConfigImportRenameValidationTest.php
rename to core/modules/config/tests/src/Kernel/ConfigImportRenameValidationTest.php
index fe4df02..5fdc052 100644
--- a/core/modules/config/src/Tests/ConfigImportRenameValidationTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigImportRenameValidationTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigImportRenameValidationTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigImportRenameValidationTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Component\Utility\Unicode;
@@ -14,7 +14,7 @@
 use Drupal\Core\Config\ConfigImporterException;
 use Drupal\Core\Config\StorageComparer;
 use Drupal\node\Entity\NodeType;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests validating renamed configuration in a configuration import.
diff --git a/core/modules/config/src/Tests/ConfigImporterMissingContentTest.php b/core/modules/config/tests/src/Kernel/ConfigImporterMissingContentTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigImporterMissingContentTest.php
rename to core/modules/config/tests/src/Kernel/ConfigImporterMissingContentTest.php
index e394123..c6dbe88 100644
--- a/core/modules/config/src/Tests/ConfigImporterMissingContentTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigImporterMissingContentTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigImporterMissingContentTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigImporterMissingContentTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\StorageComparer;
 use Drupal\entity_test\Entity\EntityTest;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests importing configuration which has missing content dependencies.
diff --git a/core/modules/config/src/Tests/ConfigImporterTest.php b/core/modules/config/tests/src/Kernel/ConfigImporterTest.php
similarity index 99%
rename from core/modules/config/src/Tests/ConfigImporterTest.php
rename to core/modules/config/tests/src/Kernel/ConfigImporterTest.php
index 3fca8c0..04a3a7f 100644
--- a/core/modules/config/src/Tests/ConfigImporterTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigImporterTest.php
@@ -2,17 +2,17 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigImporterTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigImporterTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\ConfigImporterException;
 use Drupal\Core\Config\StorageComparer;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests importing configuration from files into active configuration.
@@ -677,8 +677,9 @@ public function testInstallProfile() {
    * Tests config_get_config_directory().
    */
   public function testConfigGetConfigDirectory() {
+    global $config_directories;
     $directory = config_get_config_directory(CONFIG_SYNC_DIRECTORY);
-    $this->assertEqual($this->configDirectories[CONFIG_SYNC_DIRECTORY], $directory);
+    $this->assertEqual($config_directories[CONFIG_SYNC_DIRECTORY], $directory);
 
     $message = 'Calling config_get_config_directory() with CONFIG_ACTIVE_DIRECTORY results in an exception.';
     try {
diff --git a/core/modules/config/src/Tests/ConfigInstallTest.php b/core/modules/config/tests/src/Kernel/ConfigInstallTest.php
similarity index 98%
rename from core/modules/config/src/Tests/ConfigInstallTest.php
rename to core/modules/config/tests/src/Kernel/ConfigInstallTest.php
index 321b767..09745d1 100644
--- a/core/modules/config/src/Tests/ConfigInstallTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigInstallTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigInstallTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigInstallTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\InstallStorage;
 use Drupal\Core\Config\PreExistingConfigException;
 use Drupal\Core\Config\UnmetDependenciesException;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests installation of configuration objects in installation functionality.
diff --git a/core/modules/config/src/Tests/ConfigLanguageOverrideTest.php b/core/modules/config/tests/src/Kernel/ConfigLanguageOverrideTest.php
similarity index 97%
rename from core/modules/config/src/Tests/ConfigLanguageOverrideTest.php
rename to core/modules/config/tests/src/Kernel/ConfigLanguageOverrideTest.php
index 8cbb695..20d0519 100644
--- a/core/modules/config/src/Tests/ConfigLanguageOverrideTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigLanguageOverrideTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigLanguageOverrideTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigLanguageOverrideTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\language\Entity\ConfigurableLanguage;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Confirm that language overrides work.
diff --git a/core/modules/config/src/Tests/ConfigModuleOverridesTest.php b/core/modules/config/tests/src/Kernel/ConfigModuleOverridesTest.php
similarity index 92%
rename from core/modules/config/src/Tests/ConfigModuleOverridesTest.php
rename to core/modules/config/tests/src/Kernel/ConfigModuleOverridesTest.php
index 169a7ba..d15a529 100644
--- a/core/modules/config/src/Tests/ConfigModuleOverridesTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigModuleOverridesTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigModuleOverridesTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigModuleOverridesTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests module overrides of configuration using event subscribers.
diff --git a/core/modules/config/src/Tests/ConfigOverrideTest.php b/core/modules/config/tests/src/Kernel/ConfigOverrideTest.php
similarity index 97%
rename from core/modules/config/src/Tests/ConfigOverrideTest.php
rename to core/modules/config/tests/src/Kernel/ConfigOverrideTest.php
index b9a262d..520af73 100644
--- a/core/modules/config/src/Tests/ConfigOverrideTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigOverrideTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigOverrideTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigOverrideTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests configuration overrides via $config in settings.php.
diff --git a/core/modules/config/src/Tests/ConfigOverridesPriorityTest.php b/core/modules/config/tests/src/Kernel/ConfigOverridesPriorityTest.php
similarity index 96%
rename from core/modules/config/src/Tests/ConfigOverridesPriorityTest.php
rename to core/modules/config/tests/src/Kernel/ConfigOverridesPriorityTest.php
index e42545d..78caf27 100644
--- a/core/modules/config/src/Tests/ConfigOverridesPriorityTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigOverridesPriorityTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigOverridesPriorityTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigOverridesPriorityTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Language\Language;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests that language, module and settings.php are applied in the correct
diff --git a/core/modules/config/src/Tests/ConfigSchemaTest.php b/core/modules/config/tests/src/Kernel/ConfigSchemaTest.php
similarity index 99%
rename from core/modules/config/src/Tests/ConfigSchemaTest.php
rename to core/modules/config/tests/src/Kernel/ConfigSchemaTest.php
index a89db0e..7074a97 100644
--- a/core/modules/config/src/Tests/ConfigSchemaTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigSchemaTest.php
@@ -2,17 +2,17 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigSchemaTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigSchemaTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\InstallStorage;
 use Drupal\Core\Config\Schema\ConfigSchemaAlterException;
 use Drupal\Core\TypedData\Type\IntegerInterface;
 use Drupal\Core\TypedData\Type\StringInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests schema for configuration objects.
@@ -388,7 +388,7 @@ public function testConfigSaveWithSchema() {
     // Ensure that configuration objects with keys marked as ignored are not
     // changed when saved. The 'config_schema_test.ignore' will have been saved
     // during the installation of configuration in the setUp method.
-    $extension_path = __DIR__ . '/../../tests/config_schema_test/';
+    $extension_path = __DIR__ . '/../../config_schema_test/';
     $install_storage = new FileStorage($extension_path . InstallStorage::CONFIG_INSTALL_DIRECTORY);
     $original_data = $install_storage->read('config_schema_test.ignore');
     $installed_data = $this->config('config_schema_test.ignore')->get();
diff --git a/core/modules/config/src/Tests/ConfigSnapshotTest.php b/core/modules/config/tests/src/Kernel/ConfigSnapshotTest.php
similarity index 95%
rename from core/modules/config/src/Tests/ConfigSnapshotTest.php
rename to core/modules/config/tests/src/Kernel/ConfigSnapshotTest.php
index cbb67b7..5130428 100644
--- a/core/modules/config/src/Tests/ConfigSnapshotTest.php
+++ b/core/modules/config/tests/src/Kernel/ConfigSnapshotTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\ConfigSnapshotTest.
+ * Contains \Drupal\Tests\config\Kernel\ConfigSnapshotTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\StorageComparer;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests config snapshot creation and updating.
diff --git a/core/modules/config/src/Tests/DefaultConfigTest.php b/core/modules/config/tests/src/Kernel/DefaultConfigTest.php
similarity index 82%
rename from core/modules/config/src/Tests/DefaultConfigTest.php
rename to core/modules/config/tests/src/Kernel/DefaultConfigTest.php
index 2610c3d..7bbc6b4 100644
--- a/core/modules/config/src/Tests/DefaultConfigTest.php
+++ b/core/modules/config/tests/src/Kernel/DefaultConfigTest.php
@@ -2,15 +2,16 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\DefaultConfigTest.
+ * Contains \Drupal\Tests\config\Kernel\DefaultConfigTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
+use Drupal\config\Tests\SchemaCheckTestTrait;
 use Drupal\config_test\TestInstallStorage;
 use Drupal\Core\Config\InstallStorage;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Symfony\Component\DependencyInjection\Reference;
 
 /**
@@ -23,15 +24,6 @@ class DefaultConfigTest extends KernelTestBase {
   use SchemaCheckTestTrait;
 
   /**
-   * Modules to enable.
-   *
-   * Enable the system module so that system_config_schema_info_alter() fires.
-   *
-   * @var array
-   */
-  public static $modules = array('system', 'config_test');
-
-  /**
    * Themes which provide default configuration and need enabling.
    *
    * If a theme provides default configuration but does not have a schema
@@ -50,8 +42,8 @@ protected function setUp() {
   /**
    * {@inheritdoc}
    */
-  public function containerBuild(ContainerBuilder $container) {
-    parent::containerBuild($container);
+  public function register(ContainerBuilder $container) {
+    parent::register($container);
     $container->register('default_config_test.schema_storage')
       ->setClass('\Drupal\config_test\TestInstallStorage')
       ->addArgument(InstallStorage::CONFIG_SCHEMA_DIRECTORY);
diff --git a/core/modules/config/src/Tests/SchemaCheckTraitTest.php b/core/modules/config/tests/src/Kernel/SchemaCheckTraitTest.php
similarity index 93%
rename from core/modules/config/src/Tests/SchemaCheckTraitTest.php
rename to core/modules/config/tests/src/Kernel/SchemaCheckTraitTest.php
index 25d150d..32eed93 100644
--- a/core/modules/config/src/Tests/SchemaCheckTraitTest.php
+++ b/core/modules/config/tests/src/Kernel/SchemaCheckTraitTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\SchemaCheckTraitTest.
+ * Contains \Drupal\Tests\config\Kernel\SchemaCheckTraitTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\Schema\SchemaCheckTrait;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 
 /**
diff --git a/core/modules/config/src/Tests/SchemaConfigListenerTest.php b/core/modules/config/tests/src/Kernel/SchemaConfigListenerTest.php
similarity index 92%
rename from core/modules/config/src/Tests/SchemaConfigListenerTest.php
rename to core/modules/config/tests/src/Kernel/SchemaConfigListenerTest.php
index 58939b6..61f449a 100644
--- a/core/modules/config/src/Tests/SchemaConfigListenerTest.php
+++ b/core/modules/config/tests/src/Kernel/SchemaConfigListenerTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\SchemaConfigListenerTest.
+ * Contains \Drupal\Tests\config\Kernel\SchemaConfigListenerTest.
  */
 
-namespace Drupal\config\Tests;
+namespace Drupal\Tests\config\Kernel;
 
 use Drupal\Core\Config\Schema\SchemaIncompleteException;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the functionality of ConfigSchemaChecker in KernelTestBase tests.
diff --git a/core/modules/config/src/Tests/Storage/CachedStorageTest.php b/core/modules/config/tests/src/Kernel/Storage/CachedStorageTest.php
similarity index 90%
rename from core/modules/config/src/Tests/Storage/CachedStorageTest.php
rename to core/modules/config/tests/src/Kernel/Storage/CachedStorageTest.php
index 402d87a..1e9cf05 100644
--- a/core/modules/config/src/Tests/Storage/CachedStorageTest.php
+++ b/core/modules/config/tests/src/Kernel/Storage/CachedStorageTest.php
@@ -2,14 +2,16 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\Storage\CachedStorageTest.
+ * Contains \Drupal\Tests\config\Kernel\Storage\CachedStorageTest.
  */
 
-namespace Drupal\config\Tests\Storage;
+namespace Drupal\Tests\config\Kernel\Storage;
 
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\CachedStorage;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\Site\Settings;
+use Drupal\Core\StreamWrapper\PublicStream;
 use Symfony\Component\DependencyInjection\Reference;
 
 /**
@@ -36,8 +38,7 @@ class CachedStorageTest extends ConfigStorageTestBase {
   protected function setUp() {
     parent::setUp();
     // Create a directory.
-    $dir = $this->publicFilesDirectory . '/config';
-    mkdir($dir);
+    $dir = PublicStream::basePath() . '/config';
     $this->fileStorage = new FileStorage($dir);
     $this->storage = new CachedStorage($this->fileStorage, \Drupal::service('cache.config'));
     $this->cache = \Drupal::service('cache_factory')->get('config');
diff --git a/core/modules/config/src/Tests/Storage/ConfigStorageTestBase.php b/core/modules/config/tests/src/Kernel/Storage/ConfigStorageTestBase.php
similarity index 98%
rename from core/modules/config/src/Tests/Storage/ConfigStorageTestBase.php
rename to core/modules/config/tests/src/Kernel/Storage/ConfigStorageTestBase.php
index 412c772..c60dd68 100644
--- a/core/modules/config/src/Tests/Storage/ConfigStorageTestBase.php
+++ b/core/modules/config/tests/src/Kernel/Storage/ConfigStorageTestBase.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\Storage\ConfigStorageTestBase.
+ * Contains \Drupal\Tests\config\Kernel\Storage\ConfigStorageTestBase.
  */
 
-namespace Drupal\config\Tests\Storage;
+namespace Drupal\Tests\config\Kernel\Storage;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Base class for testing storage operations.
diff --git a/core/modules/config/src/Tests/Storage/DatabaseStorageTest.php b/core/modules/config/tests/src/Kernel/Storage/DatabaseStorageTest.php
similarity index 90%
rename from core/modules/config/src/Tests/Storage/DatabaseStorageTest.php
rename to core/modules/config/tests/src/Kernel/Storage/DatabaseStorageTest.php
index 882b072..3af7496 100644
--- a/core/modules/config/src/Tests/Storage/DatabaseStorageTest.php
+++ b/core/modules/config/tests/src/Kernel/Storage/DatabaseStorageTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\Storage\DatabaseStorageTest.
+ * Contains \Drupal\Tests\config\Kernel\Storage\DatabaseStorageTest.
  */
 
-namespace Drupal\config\Tests\Storage;
+namespace Drupal\Tests\config\Kernel\Storage;
 
 use Drupal\Core\Config\DatabaseStorage;
 
diff --git a/core/modules/config/src/Tests/Storage/FileStorageTest.php b/core/modules/config/tests/src/Kernel/Storage/FileStorageTest.php
similarity index 84%
rename from core/modules/config/src/Tests/Storage/FileStorageTest.php
rename to core/modules/config/tests/src/Kernel/Storage/FileStorageTest.php
index a37f084..c98ac84 100644
--- a/core/modules/config/src/Tests/Storage/FileStorageTest.php
+++ b/core/modules/config/tests/src/Kernel/Storage/FileStorageTest.php
@@ -2,14 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\config\Tests\Storage\FileStorageTest.
+ * Contains \Drupal\Tests\config\Kernel\Storage\FileStorageTest.
  */
 
-namespace Drupal\config\Tests\Storage;
+namespace Drupal\Tests\config\Kernel\Storage;
 
 use Drupal\Component\Serialization\Yaml;
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\UnsupportedDataTypeConfigException;
+use Drupal\Core\StreamWrapper\PublicStream;
 
 /**
  * Tests FileStorage operations.
@@ -31,8 +32,7 @@ class FileStorageTest extends ConfigStorageTestBase {
   protected function setUp() {
     parent::setUp();
     // Create a directory.
-    $this->directory = $this->publicFilesDirectory . '/config';
-    mkdir($this->directory);
+    $this->directory = PublicStream::basePath() . '/config';
     $this->storage = new FileStorage($this->directory);
     $this->invalidStorage = new FileStorage($this->directory . '/nonexisting');
 
@@ -75,12 +75,6 @@ public function testlistAll() {
     //   is case-insensitive.
     $this->assertIdentical(['system.performance'], $this->storage->listAll('system'), 'The FileStorage::listAll() with prefix works.');
     $this->assertIdentical([], $this->storage->listAll('System'), 'The FileStorage::listAll() is case sensitive.');
-
-    // Initialize FileStorage with absolute file path.
-    $absolute_path = realpath($this->directory);
-    $storage_absolute_path = new FileStorage($absolute_path);
-    $config_files = $storage_absolute_path->listAll();
-    $this->assertIdentical($config_files, $expected_files, 'Absolute path, two config files found.');
   }
 
   /**
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationConfigImportTest.php b/core/modules/content_translation/tests/src/Kernel/ContentTranslationConfigImportTest.php
similarity index 95%
rename from core/modules/content_translation/src/Tests/ContentTranslationConfigImportTest.php
rename to core/modules/content_translation/tests/src/Kernel/ContentTranslationConfigImportTest.php
index 9d3450c..62fcb92 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationConfigImportTest.php
+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationConfigImportTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\content_translation\Tests\ContentTranslationConfigImportTest.
+ * Contains \Drupal\Tests\content_translation\Kernel\ContentTranslationConfigImportTest.
  */
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Kernel;
 
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\StorageComparer;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests content translation updates performed during config import.
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationSettingsApiTest.php b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSettingsApiTest.php
similarity index 84%
rename from core/modules/content_translation/src/Tests/ContentTranslationSettingsApiTest.php
rename to core/modules/content_translation/tests/src/Kernel/ContentTranslationSettingsApiTest.php
index 397288a..a9f3628 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationSettingsApiTest.php
+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSettingsApiTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\content_translation\Tests\ContentTranslationSettingsApiTest.
+ * Contains \Drupal\Tests\content_translation\Kernel\ContentTranslationSettingsApiTest.
  */
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the content translation settings API.
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationSyncUnitTest.php b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
similarity index 98%
rename from core/modules/content_translation/src/Tests/ContentTranslationSyncUnitTest.php
rename to core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
index ab1e1cb..6c50554 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationSyncUnitTest.php
+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\content_translation\Tests\ContentTranslationSyncUnitTest.
+ * Contains \Drupal\Tests\content_translation\Kernel\ContentTranslationSyncUnitTest.
  */
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
 use Drupal\content_translation\FieldTranslationSynchronizer;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the field synchronization logic.
diff --git a/core/modules/contextual/src/Tests/ContextualUnitTest.php b/core/modules/contextual/tests/src/Kernel/ContextualUnitTest.php
similarity index 95%
rename from core/modules/contextual/src/Tests/ContextualUnitTest.php
rename to core/modules/contextual/tests/src/Kernel/ContextualUnitTest.php
index f164051..84f7e95 100644
--- a/core/modules/contextual/src/Tests/ContextualUnitTest.php
+++ b/core/modules/contextual/tests/src/Kernel/ContextualUnitTest.php
@@ -2,12 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\contextual\Tests\ContextualUnitTest.
+ * Contains \Drupal\Tests\contextual\Kernel\ContextualUnitTest.
  */
 
-namespace Drupal\contextual\Tests;
+namespace Drupal\Tests\contextual\Kernel;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests all edge cases of converting from #contextual_links to ids and vice
diff --git a/core/modules/dblog/src/Tests/DbLogFormInjectionTest.php b/core/modules/dblog/tests/src/Kernel/DbLogFormInjectionTest.php
similarity index 94%
rename from core/modules/dblog/src/Tests/DbLogFormInjectionTest.php
rename to core/modules/dblog/tests/src/Kernel/DbLogFormInjectionTest.php
index 62fa234..ffded0b 100644
--- a/core/modules/dblog/src/Tests/DbLogFormInjectionTest.php
+++ b/core/modules/dblog/tests/src/Kernel/DbLogFormInjectionTest.php
@@ -1,17 +1,17 @@
 <?php
 /**
  * @file
- * Contains \Drupal\dblog\Tests\DbLogFormInjectionTest.
+ * Contains \Drupal\Tests\dblog\Kernel\DbLogFormInjectionTest.
  */
 
-namespace Drupal\dblog\Tests;
+namespace Drupal\Tests\dblog\Kernel;
 
 
 use Drupal\Core\DependencyInjection\DependencySerializationTrait;
 use Drupal\Core\Form\FormInterface;
 use Drupal\Core\Form\FormState;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\User;
 
 /**
diff --git a/core/modules/editor/src/Tests/EditorFileReferenceFilterTest.php b/core/modules/editor/tests/src/Kernel/EditorFileReferenceFilterTest.php
similarity index 96%
rename from core/modules/editor/src/Tests/EditorFileReferenceFilterTest.php
rename to core/modules/editor/tests/src/Kernel/EditorFileReferenceFilterTest.php
index aac6ae0..ee36393 100644
--- a/core/modules/editor/src/Tests/EditorFileReferenceFilterTest.php
+++ b/core/modules/editor/tests/src/Kernel/EditorFileReferenceFilterTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\editor\Tests\EditorFileReferenceFilterTest.
+ * Contains \Drupal\Tests\editor\Kernel\EditorFileReferenceFilterTest.
  */
 
-namespace Drupal\editor\Tests;
+namespace Drupal\Tests\editor\Kernel;
 
 use Drupal\Core\Cache\Cache;
 use Drupal\file\Entity\File;
-use Drupal\simpletest\KernelTestBase;
 use Drupal\filter\FilterPluginCollection;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests Editor module's file reference filter.
diff --git a/core/modules/editor/src/Tests/EditorManagerTest.php b/core/modules/editor/tests/src/Kernel/EditorManagerTest.php
similarity index 96%
rename from core/modules/editor/src/Tests/EditorManagerTest.php
rename to core/modules/editor/tests/src/Kernel/EditorManagerTest.php
index 498e33e..a76d55e 100644
--- a/core/modules/editor/src/Tests/EditorManagerTest.php
+++ b/core/modules/editor/tests/src/Kernel/EditorManagerTest.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\editor\Tests\EditorManagerTest.
+ * Contains \Drupal\Tests\editor\Kernel\EditorManagerTest.
  */
 
-namespace Drupal\editor\Tests;
+namespace Drupal\Tests\editor\Kernel;
 
 use Drupal\editor\Entity\Editor;
-use Drupal\simpletest\KernelTestBase;
 use Drupal\filter\Entity\FilterFormat;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests detection of text editors and correct generation of attachments.
diff --git a/core/modules/field/src/Tests/FieldDefinitionIntegrityTest.php b/core/modules/field/tests/src/Kernel/FieldDefinitionIntegrityTest.php
similarity index 95%
rename from core/modules/field/src/Tests/FieldDefinitionIntegrityTest.php
rename to core/modules/field/tests/src/Kernel/FieldDefinitionIntegrityTest.php
index abef067..ed889bd 100644
--- a/core/modules/field/src/Tests/FieldDefinitionIntegrityTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldDefinitionIntegrityTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\field\Tests\FieldDefinitionIntegrityTest.
+ * Contains \Drupal\Tests\field\Kernel\FieldDefinitionIntegrityTest.
  */
 
-namespace Drupal\field\Tests;
+namespace Drupal\Tests\field\Kernel;
 
 use Drupal\Core\Extension\Extension;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the integrity of field API plugin definitions.
@@ -18,10 +18,14 @@
 class FieldDefinitionIntegrityTest extends KernelTestBase {
 
   /**
-   * {@inheritdoc}
+   * @var array
    */
-  protected function setUp() {
-    parent::setUp();
+  public static $modules = ['system'];
+
+  /**
+   * Tests the integrity of field plugin definitions.
+   */
+  public function testFieldPluginDefinitionIntegrity() {
 
     // Enable all core modules that provide field plugins.
     $modules = system_rebuild_module_data();
@@ -38,12 +42,7 @@ protected function setUp() {
       return FALSE;
     });
     $this->enableModules(array_keys($modules));
-  }
 
-  /**
-   * Tests the integrity of field plugin definitions.
-   */
-  public function testFieldPluginDefinitionIntegrity() {
     /** @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface $field_type_manager */
     $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
 
diff --git a/core/modules/field_ui/src/Tests/EntityDisplayTest.php b/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
similarity index 99%
rename from core/modules/field_ui/src/Tests/EntityDisplayTest.php
rename to core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
index 1c9332b..2be4747 100644
--- a/core/modules/field_ui/src/Tests/EntityDisplayTest.php
+++ b/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\field_ui\Tests\EntityDisplayTest.
+ * Contains \Drupal\Tests\field_ui\Kernel\EntityDisplayTest.
  */
 
-namespace Drupal\field_ui\Tests;
+namespace Drupal\Tests\field_ui\Kernel;
 
 use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Component\Utility\Unicode;
@@ -19,7 +19,7 @@
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\node\Entity\NodeType;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\Role;
 
 /**
diff --git a/core/modules/field_ui/src/Tests/EntityFormDisplayTest.php b/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
similarity index 98%
rename from core/modules/field_ui/src/Tests/EntityFormDisplayTest.php
rename to core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
index 1840218..c8bced0 100644
--- a/core/modules/field_ui/src/Tests/EntityFormDisplayTest.php
+++ b/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
@@ -2,16 +2,16 @@
 
 /**
  * @file
- * Contains \Drupal\field_ui\Tests\EntityFormDisplayTest.
+ * Contains \Drupal\Tests\field_ui\Kernel\EntityFormDisplayTest.
  */
 
-namespace Drupal\field_ui\Tests;
+namespace Drupal\Tests\field_ui\Kernel;
 
 use Drupal\Core\Entity\Entity\EntityFormDisplay;
 use Drupal\Core\Entity\Entity\EntityFormMode;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the entity display configuration entities.
diff --git a/core/modules/file/src/Tests/CopyTest.php b/core/modules/file/tests/src/Kernel/CopyTest.php
similarity index 98%
rename from core/modules/file/src/Tests/CopyTest.php
rename to core/modules/file/tests/src/Kernel/CopyTest.php
index 68c589b..e86f39a 100644
--- a/core/modules/file/src/Tests/CopyTest.php
+++ b/core/modules/file/tests/src/Kernel/CopyTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\CopyTest.
+ * Contains \Drupal\Tests\file\Kernel\CopyTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/DeleteTest.php b/core/modules/file/tests/src/Kernel/DeleteTest.php
similarity index 96%
rename from core/modules/file/src/Tests/DeleteTest.php
rename to core/modules/file/tests/src/Kernel/DeleteTest.php
index 1ec0376..743528a 100644
--- a/core/modules/file/src/Tests/DeleteTest.php
+++ b/core/modules/file/tests/src/Kernel/DeleteTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\DeleteTest.
+ * Contains \Drupal\Tests\file\Kernel\DeleteTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/FileManagedUnitTestBase.php b/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
similarity index 98%
rename from core/modules/file/src/Tests/FileManagedUnitTestBase.php
rename to core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
index 62ee4c2..e01717f 100644
--- a/core/modules/file/src/Tests/FileManagedUnitTestBase.php
+++ b/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
@@ -2,14 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\FileManagedUnitTestBase.
+ * Contains \Drupal\Tests\file\Kernel\FileManagedUnitTestBase.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 use Drupal\file\FileInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\User;
 
 /**
diff --git a/core/modules/file/src/Tests/Formatter/FileEntityFormatterTest.php b/core/modules/file/tests/src/Kernel/Formatter/FileEntityFormatterTest.php
similarity index 96%
rename from core/modules/file/src/Tests/Formatter/FileEntityFormatterTest.php
rename to core/modules/file/tests/src/Kernel/Formatter/FileEntityFormatterTest.php
index 1c9a275..61f6891 100644
--- a/core/modules/file/src/Tests/Formatter/FileEntityFormatterTest.php
+++ b/core/modules/file/tests/src/Kernel/Formatter/FileEntityFormatterTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\Formatter\FileEntityFormatterTest.
+ * Contains \Drupal\Tests\file\Kernel\Formatter\FileEntityFormatterTest.
  */
 
-namespace Drupal\file\Tests\Formatter;
+namespace Drupal\Tests\file\Kernel\Formatter;
 
 use Drupal\Core\Entity\Entity\EntityViewDisplay;
 use Drupal\Core\Url;
 use Drupal\file\Entity\File;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests the default file formatter.
diff --git a/core/modules/file/src/Tests/LoadTest.php b/core/modules/file/tests/src/Kernel/LoadTest.php
similarity index 98%
rename from core/modules/file/src/Tests/LoadTest.php
rename to core/modules/file/tests/src/Kernel/LoadTest.php
index 7a0fde9..19c1675 100644
--- a/core/modules/file/src/Tests/LoadTest.php
+++ b/core/modules/file/tests/src/Kernel/LoadTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\LoadTest.
+ * Contains \Drupal\Tests\file\Kernel\LoadTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/MoveTest.php b/core/modules/file/tests/src/Kernel/MoveTest.php
similarity index 98%
rename from core/modules/file/src/Tests/MoveTest.php
rename to core/modules/file/tests/src/Kernel/MoveTest.php
index 8177992..34a1254 100644
--- a/core/modules/file/src/Tests/MoveTest.php
+++ b/core/modules/file/tests/src/Kernel/MoveTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\MoveTest.
+ * Contains \Drupal\Tests\file\Kernel\MoveTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/SaveDataTest.php b/core/modules/file/tests/src/Kernel/SaveDataTest.php
similarity index 98%
rename from core/modules/file/src/Tests/SaveDataTest.php
rename to core/modules/file/tests/src/Kernel/SaveDataTest.php
index 4ca49ad..0bcaaf7 100644
--- a/core/modules/file/src/Tests/SaveDataTest.php
+++ b/core/modules/file/tests/src/Kernel/SaveDataTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\SaveDataTest.
+ * Contains \Drupal\Tests\file\Kernel\SaveDataTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/SaveTest.php b/core/modules/file/tests/src/Kernel/SaveTest.php
similarity index 97%
rename from core/modules/file/src/Tests/SaveTest.php
rename to core/modules/file/tests/src/Kernel/SaveTest.php
index ecd7d60..c3dfd94 100644
--- a/core/modules/file/src/Tests/SaveTest.php
+++ b/core/modules/file/tests/src/Kernel/SaveTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\SaveTest.
+ * Contains \Drupal\Tests\file\Kernel\SaveTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 use Drupal\file\Entity\File;
 
diff --git a/core/modules/file/src/Tests/SpaceUsedTest.php b/core/modules/file/tests/src/Kernel/SpaceUsedTest.php
similarity index 96%
rename from core/modules/file/src/Tests/SpaceUsedTest.php
rename to core/modules/file/tests/src/Kernel/SpaceUsedTest.php
index 3a4e8c3..1a9dd28 100644
--- a/core/modules/file/src/Tests/SpaceUsedTest.php
+++ b/core/modules/file/tests/src/Kernel/SpaceUsedTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\SpaceUsedTest.
+ * Contains \Drupal\Tests\file\Kernel\SpaceUsedTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 use Drupal\file\Entity\File;
 
 /**
diff --git a/core/modules/file/src/Tests/UsageTest.php b/core/modules/file/tests/src/Kernel/UsageTest.php
similarity index 98%
rename from core/modules/file/src/Tests/UsageTest.php
rename to core/modules/file/tests/src/Kernel/UsageTest.php
index 0ed0037..b28c4f5 100644
--- a/core/modules/file/src/Tests/UsageTest.php
+++ b/core/modules/file/tests/src/Kernel/UsageTest.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\UsageTest.
+ * Contains \Drupal\Tests\file\Kernel\UsageTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
 
 /**
  * Tests file usage functions.
diff --git a/core/modules/file/src/Tests/ValidateTest.php b/core/modules/file/tests/src/Kernel/ValidateTest.php
similarity index 89%
rename from core/modules/file/src/Tests/ValidateTest.php
rename to core/modules/file/tests/src/Kernel/ValidateTest.php
index 25076b0..148a694 100644
--- a/core/modules/file/src/Tests/ValidateTest.php
+++ b/core/modules/file/tests/src/Kernel/ValidateTest.php
@@ -2,10 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\ValidateTest.
+ * Contains \Drupal\Tests\file\Kernel\ValidateTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
+
+use Drupal\Tests\file\Kernel\FileManagedUnitTestBase;
 
 /**
  * Tests the file_validate() function.
diff --git a/core/modules/file/src/Tests/ValidatorTest.php b/core/modules/file/tests/src/Kernel/ValidatorTest.php
similarity index 98%
rename from core/modules/file/src/Tests/ValidatorTest.php
rename to core/modules/file/tests/src/Kernel/ValidatorTest.php
index be3e098..55b170b 100644
--- a/core/modules/file/src/Tests/ValidatorTest.php
+++ b/core/modules/file/tests/src/Kernel/ValidatorTest.php
@@ -2,10 +2,11 @@
 
 /**
  * @file
- * Contains \Drupal\file\Tests\ValidatorTest.
+ * Contains \Drupal\Tests\file\Kernel\ValidatorTest.
  */
 
-namespace Drupal\file\Tests;
+namespace Drupal\Tests\file\Kernel;
+
 use Drupal\file\Entity\File;
 
 /**
diff --git a/core/modules/filter/src/Tests/FilterCrudTest.php b/core/modules/filter/tests/src/Kernel/FilterCrudTest.php
similarity index 96%
rename from core/modules/filter/src/Tests/FilterCrudTest.php
rename to core/modules/filter/tests/src/Kernel/FilterCrudTest.php
index db0516b..1f54f65 100644
--- a/core/modules/filter/src/Tests/FilterCrudTest.php
+++ b/core/modules/filter/tests/src/Kernel/FilterCrudTest.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains \Drupal\filter\Tests\FilterCrudTest.
+ * Contains \Drupal\Tests\filter\Kernel\FilterCrudTest.
  */
 
-namespace Drupal\filter\Tests;
+namespace Drupal\Tests\filter\Kernel;
 
 use Drupal\filter\Entity\FilterFormat;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests creation, loading, updating, deleting of text formats and filters.
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.module b/core/modules/system/tests/modules/entity_test/entity_test.module
index 668c81d..444fbe5 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.module
+++ b/core/modules/system/tests/modules/entity_test/entity_test.module
@@ -250,7 +250,7 @@ function entity_test_entity_extra_field_info() {
   $extra['entity_test']['bundle_with_extra_fields'] = array(
     'display' => array(
       // Note: those extra fields do not currently display anything, they are
-      // just used in \Drupal\field_ui\Tests\EntityDisplayTest to test the
+      // just used in \Drupal\Tests\field_ui\Kernel\EntityDisplayTest to test the
       // behavior of entity display objects.
       'display_extra_field' => array(
         'label' => t('Display extra field'),
diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index d20f341..68b618e 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -192,6 +192,22 @@
   protected $strictConfigSchema = TRUE;
 
   /**
+   * An array of config object names that are excluded from schema checking.
+   *
+   * @var string[]
+   */
+  protected static $configSchemaCheckerExclusions = array(
+    // Following are used to test lack of or partial schema. Where partial
+    // schema is provided, that is explicitly tested in specific tests.
+    'config_schema_test.noschema',
+    'config_schema_test.someschema',
+    'config_schema_test.schema_data_types',
+    'config_schema_test.no_schema_data_types',
+    // Used to test application of schema to filtering of configuration.
+    'config_test.dynamic.system',
+  );
+
+  /**
    * {@inheritdoc}
    */
   public static function setUpBeforeClass() {
@@ -578,6 +594,7 @@ public function register(ContainerBuilder $container) {
       $container
         ->register('simpletest.config_schema_checker', 'Drupal\Core\Config\Testing\ConfigSchemaChecker')
         ->addArgument(new Reference('config.typed'))
+        ->addArgument($this->getConfigSchemaExclusions())
         ->addTag('event_subscriber');
     }
 
@@ -598,6 +615,25 @@ public function register(ContainerBuilder $container) {
   }
 
   /**
+   * Gets the config schema exclusions for this test.
+   *
+   * @return string[]
+   *   An array of config object names that are excluded from schema checking.
+   */
+  protected function getConfigSchemaExclusions() {
+    $class = get_class($this);
+    $exceptions = [];
+    while ($class) {
+      if (property_exists($class, 'configSchemaCheckerExclusions')) {
+        $exceptions = array_merge($exceptions, $class::$configSchemaCheckerExclusions);
+      }
+      $class = get_parent_class($class);
+    }
+    // Filter out any duplicates.
+    return array_unique($exceptions);
+  }
+
+  /**
    * {@inheritdoc}
    */
   protected function assertPostConditions() {
