diff --git a/core/modules/system/src/Tests/Form/ExternalFormUrlTest.php b/core/modules/system/tests/src/Kernel/Form/ExternalFormUrlTest.php
similarity index 97%
rename from core/modules/system/src/Tests/Form/ExternalFormUrlTest.php
rename to core/modules/system/tests/src/Kernel/Form/ExternalFormUrlTest.php
index f179ec9..e756374 100644
--- a/core/modules/system/src/Tests/Form/ExternalFormUrlTest.php
+++ b/core/modules/system/tests/src/Kernel/Form/ExternalFormUrlTest.php
@@ -5,11 +5,11 @@
  * Contains \Drupal\system\Tests\Form\ExternalFormUrlTest.
  */
 
-namespace Drupal\system\Tests\Form;
+namespace Drupal\Tests\system\Kernel\Form;
 
 use Drupal\Core\Form\FormInterface;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\User;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -67,7 +67,6 @@ protected function setUp() {
     ]);
     $test_user->save();
     \Drupal::service('current_user')->setAccount($test_user);
-
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Form/FormCacheTest.php b/core/modules/system/tests/src/Kernel/Form/FormCacheTest.php
similarity index 97%
rename from core/modules/system/src/Tests/Form/FormCacheTest.php
rename to core/modules/system/tests/src/Kernel/Form/FormCacheTest.php
index 77d259e..bc8ed81 100644
--- a/core/modules/system/src/Tests/Form/FormCacheTest.php
+++ b/core/modules/system/tests/src/Kernel/Form/FormCacheTest.php
@@ -5,12 +5,12 @@
  * Contains \Drupal\system\Tests\Form\FormCacheTest.
  */
 
-namespace Drupal\system\Tests\Form;
+namespace Drupal\Tests\system\Kernel\Form;
 
 use Drupal\Core\Form\FormState;
 use Drupal\Core\Session\AnonymousUserSession;
 use Drupal\Core\Session\UserSession;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests \Drupal::formBuilder()->setCache() and
diff --git a/core/modules/system/src/Tests/Form/FormDefaultHandlersTest.php b/core/modules/system/tests/src/Kernel/Form/FormDefaultHandlersTest.php
similarity index 97%
rename from core/modules/system/src/Tests/Form/FormDefaultHandlersTest.php
rename to core/modules/system/tests/src/Kernel/Form/FormDefaultHandlersTest.php
index 94187af..a86bea4 100644
--- a/core/modules/system/src/Tests/Form/FormDefaultHandlersTest.php
+++ b/core/modules/system/tests/src/Kernel/Form/FormDefaultHandlersTest.php
@@ -5,12 +5,12 @@
  * Contains \Drupal\system\Tests\Form\FormDefaultHandlersTest.
  */
 
-namespace Drupal\system\Tests\Form;
+namespace Drupal\Tests\system\Kernel\Form;
 
 use Drupal\Core\Form\FormInterface;
 use Drupal\Core\Form\FormState;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests automatically added form handlers.
diff --git a/core/modules/system/src/Tests/Image/ToolkitGdTest.php b/core/modules/system/tests/src/Kernel/Image/ToolkitGdTest.php
similarity index 98%
rename from core/modules/system/src/Tests/Image/ToolkitGdTest.php
rename to core/modules/system/tests/src/Kernel/Image/ToolkitGdTest.php
index 1c61235..f47d801 100644
--- a/core/modules/system/src/Tests/Image/ToolkitGdTest.php
+++ b/core/modules/system/tests/src/Kernel/Image/ToolkitGdTest.php
@@ -5,11 +5,12 @@
  * Contains \Drupal\system\Tests\Image\ToolkitGdTest.
  */
 
-namespace Drupal\system\Tests\Image;
+namespace Drupal\Tests\system\Kernel\Image;
 
 use Drupal\Core\Image\ImageInterface;
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\Core\Site\Settings;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests that core image manipulations work properly: scale, resize, rotate,
@@ -253,7 +254,7 @@ function testManipulations() {
     }
 
     // Prepare a directory for test file results.
-    $directory = $this->publicFilesDirectory .'/imagetest';
+    $directory = Settings::get('file_public_path') .'/imagetest';
     file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
 
     foreach ($files as $file) {
@@ -429,7 +430,7 @@ public function testResourceDestruction() {
    */
   function testGifTransparentImages() {
     // Prepare a directory for test file results.
-    $directory = $this->publicFilesDirectory .'/imagetest';
+    $directory = Settings::get('file_public_path') .'/imagetest';
     file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
 
     // Test loading an indexed GIF image with transparent color set.
diff --git a/core/modules/system/src/Tests/Form/TriggeringElementProgrammedUnitTest.php b/core/tests/Drupal/KernelTests/Core/Form/TriggeringElementProgrammedUnitTest.php
similarity index 95%
rename from core/modules/system/src/Tests/Form/TriggeringElementProgrammedUnitTest.php
rename to core/tests/Drupal/KernelTests/Core/Form/TriggeringElementProgrammedUnitTest.php
index ae6b82c..d63eb4c 100644
--- a/core/modules/system/src/Tests/Form/TriggeringElementProgrammedUnitTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Form/TriggeringElementProgrammedUnitTest.php
@@ -5,12 +5,12 @@
  * Contains \Drupal\system\Tests\Form\TriggeringElementProgrammedUnitTest.
  */
 
-namespace Drupal\system\Tests\Form;
+namespace Drupal\KernelTests\Core\Form;
 
 use Drupal\Core\Form\FormInterface;
 use Drupal\Core\Form\FormState;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests detection of triggering_element for programmed form submissions.
@@ -19,8 +19,6 @@
  */
 class TriggeringElementProgrammedUnitTest extends KernelTestBase implements FormInterface {
 
-  public static $modules = array('system');
-
   /**
    * {@inheritdoc}
    */
diff --git a/core/modules/system/src/Tests/HttpKernel/StackKernelIntegrationTest.php b/core/tests/Drupal/KernelTests/Core/HttpKernel/StackKernelIntegrationTest.php
similarity index 94%
rename from core/modules/system/src/Tests/HttpKernel/StackKernelIntegrationTest.php
rename to core/tests/Drupal/KernelTests/Core/HttpKernel/StackKernelIntegrationTest.php
index d976b37..c4d7ec7 100644
--- a/core/modules/system/src/Tests/HttpKernel/StackKernelIntegrationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/HttpKernel/StackKernelIntegrationTest.php
@@ -5,10 +5,10 @@
  * Contains \Drupal\system\Tests\HttpKernel\StackKernelIntegrationTest.
  */
 
-namespace Drupal\system\Tests\HttpKernel;
+namespace Drupal\KernelTests\Core\HttpKernel;
 
-use Drupal\simpletest\KernelTestBase;
 use Drupal\Core\Url;
+use Drupal\KernelTests\KernelTestBase;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 
@@ -57,7 +57,7 @@ public function testLazyLateMiddlewares() {
     $this->assertFalse($this->container->getDefinition('http_kernel.basic')->isLazy(), 'lazy flag on http_kernel.basic definition is not set');
 
     \Drupal::service('module_installer')->install(['page_cache']);
-    $this->container = $this->kernel->rebuildContainer();
+    $this->container = \Drupal::service('kernel')->rebuildContainer();
 
     $this->assertFalse($this->container->getDefinition('http_middleware.reverse_proxy')->isLazy(), 'lazy flag on http_middleware.reverse_proxy definition is not set');
     $this->assertFalse($this->container->getDefinition('http_middleware.page_cache')->isLazy(), 'lazy flag on http_middleware.page_cache definition is not set');
diff --git a/core/modules/system/src/Tests/Installer/InstallerLanguageTest.php b/core/tests/Drupal/KernelTests/Core/Installer/InstallerLanguageTest.php
similarity index 96%
rename from core/modules/system/src/Tests/Installer/InstallerLanguageTest.php
rename to core/tests/Drupal/KernelTests/Core/Installer/InstallerLanguageTest.php
index 417cfd0..3d798b0 100644
--- a/core/modules/system/src/Tests/Installer/InstallerLanguageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Installer/InstallerLanguageTest.php
@@ -5,10 +5,10 @@
  * Contains \Drupal\system\Tests\Installer\InstallerLanguageTest.
  */
 
-namespace Drupal\system\Tests\Installer;
+namespace Drupal\KernelTests\Core\Installer;
 
-use Drupal\simpletest\KernelTestBase;
 use Drupal\Core\StringTranslation\Translator\FileTranslation;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Tests for installer language support.