diff --git a/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php b/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
index 7b5d4d0..c3d3e30 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
@@ -94,11 +94,6 @@ class ResolvedLibraryDefinitionsFilesMatchTest extends KernelTestBase {
   protected function setUp() {
     parent::setUp();
 
-    $this->themeHandler = $this->container->get('theme_handler');
-    $this->themeInitialization = $this->container->get('theme.initialization');
-    $this->themeManager = $this->container->get('theme.manager');
-    $this->libraryDiscovery = $this->container->get('library.discovery');
-
     // Install all core themes.
     sort($this->allThemes);
     $this->container->get('theme_installer')->install($this->allThemes);
@@ -114,9 +109,14 @@ protected function setUp() {
       return TRUE;
     });
     $this->allModules = array_keys($all_modules);
+    $this->allModules[] = 'system';
     sort($this->allModules);
-    print_r($this->allModules);
     $this->container->get('module_installer')->install($this->allModules);
+
+    $this->themeHandler = $this->container->get('theme_handler');
+    $this->themeInitialization = $this->container->get('theme.initialization');
+    $this->themeManager = $this->container->get('theme.manager');
+    $this->libraryDiscovery = $this->container->get('library.discovery');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php b/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
index 8eadd70..f26dc98 100644
--- a/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
+++ b/core/tests/Drupal/KernelTests/Core/DrupalKernel/DrupalKernelTest.php
@@ -15,31 +15,16 @@
 class DrupalKernelTest extends KernelTestBase {
 
   protected function setUp() {
-    // DrupalKernel relies on global $config_directories and requires those
-    // directories to exist. Therefore, create the directories, but do not
-    // invoke KernelTestBase::setUp(), since that would set up further
-    // environment aspects, which would distort this test, because it tests
-    // the DrupalKernel (re-)building itself.
-    $this->prepareConfigDirectories();
-
+    $this->root = dirname(dirname(dirname(dirname(dirname(dirname(__DIR__))))));
     $this->setSetting('php_storage', array('service_container' => array(
       'bin' => 'service_container',
       'class' => 'Drupal\Component\PhpStorage\MTimeProtectedFileStorage',
-      'directory' => DRUPAL_ROOT . '/' . $this->publicFilesDirectory . '/php',
-      'secret' => Settings::getHashSalt(),
+      'directory' => $this->root . '/' . $this->publicFilesDirectory . '/php',
+      'secret' => 'test-secret',
     )));
   }
 
   /**
-   * {@inheritdoc}
-   */
-  protected function prepareConfigDirectories() {
-    \Drupal::setContainer($this->originalContainer);
-    parent::prepareConfigDirectories();
-    \Drupal::unsetContainer();
-  }
-
-  /**
    * Build a kernel for testings.
    *
    * Because the bootstrap is in DrupalKernel::boot and that involved loading
@@ -56,10 +41,10 @@ protected function prepareConfigDirectories() {
    */
   protected function getTestKernel(Request $request, array $modules_enabled = NULL) {
     // Manually create kernel to avoid replacing settings.
-    $class_loader = require DRUPAL_ROOT . '/autoload.php';
+    $class_loader = require $this->root . '/autoload.php';
     $kernel = DrupalKernel::createFromRequest($request, $class_loader, 'testing');
-    $this->settingsSet('container_yamls', []);
-    $this->settingsSet('hash_salt', $this->databasePrefix);
+    $this->setSetting('container_yamls', []);
+    $this->setSetting('hash_salt', $this->databasePrefix);
     if (isset($modules_enabled)) {
       $kernel->updateModules($modules_enabled);
     }
@@ -153,7 +138,7 @@ public function testCompileDIC() {
    */
   public function testRepeatedBootWithDifferentEnvironment() {
     $request = Request::createFromGlobals();
-    $class_loader = require DRUPAL_ROOT . '/autoload.php';
+    $class_loader = require $this->root . '/autoload.php';
 
     $environments = [
       'testing1',
@@ -164,8 +149,8 @@ public function testRepeatedBootWithDifferentEnvironment() {
 
     foreach ($environments as $environment) {
       $kernel = DrupalKernel::createFromRequest($request, $class_loader, $environment);
-      $this->settingsSet('container_yamls', []);
-      $this->settingsSet('hash_salt', $this->databasePrefix);
+      $this->setSetting('container_yamls', []);
+      $this->setSetting('hash_salt', $this->databasePrefix);
       $kernel->boot();
     }
 
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/StableLibraryOverrideTest.php b/core/tests/Drupal/KernelTests/Core/Theme/StableLibraryOverrideTest.php
index 00e964d..400206d 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/StableLibraryOverrideTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/StableLibraryOverrideTest.php
@@ -57,10 +57,6 @@ class StableLibraryOverrideTest extends KernelTestBase {
   protected function setUp() {
     parent::setUp();
 
-    $this->themeManager = $this->container->get('theme.manager');
-    $this->themeInitialization = $this->container->get('theme.initialization');
-    $this->libraryDiscovery = $this->container->get('library.discovery');
-
     $this->container->get('theme_installer')->install(['stable']);
 
     // Enable all core modules.
@@ -74,8 +70,13 @@ protected function setUp() {
       return TRUE;
     });
     $this->allModules = array_keys($all_modules);
+    $this->allModules[] = 'system';
     sort($this->allModules);
     $this->container->get('module_installer')->install($this->allModules);
+
+    $this->themeManager = $this->container->get('theme.manager');
+    $this->themeInitialization = $this->container->get('theme.initialization');
+    $this->libraryDiscovery = $this->container->get('library.discovery');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index ad10290..08e599a 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -1010,7 +1010,7 @@ protected function render(array &$elements) {
    *   \Drupal\Core\Site\Settings::get() to perform custom merges.
    */
   protected function setSetting($name, $value) {
-    $settings = Settings::getAll();
+    $settings = Settings::getInstance() ? Settings::getAll() : [];
     $settings[$name] = $value;
     new Settings($settings);
   }