diff --git a/core/modules/simpletest/lib/Drupal/simpletest/InstallerTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/InstallerTestBase.php
index 899c7d8..d4b9992 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/InstallerTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/InstallerTestBase.php
@@ -7,7 +7,11 @@
 
 namespace Drupal\simpletest;
 
+use Drupal\Core\Language\Language;
 use Drupal\Core\Session\UserSession;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Base class for testing the interactive installer.
@@ -91,6 +95,25 @@ protected function setUp() {
     // @see WebTestBase::translatePostValues()
     $this->parameters = $this->installParameters();
 
+    // Set up a minimal container (required by WebTestBase).
+    // @see install_begin_request()
+    $request = Request::create($GLOBALS['base_url'] . '/core/install.php');
+    $this->container = new ContainerBuilder();
+    $this->container
+      ->set('request', $request);
+    $this->container
+      ->setParameter('language.default_values', Language::$defaultValues);
+    $this->container
+      ->register('language.default', 'Drupal\Core\Language\LanguageDefault')
+      ->addArgument('%language.default_values%');
+    $this->container
+      ->register('language_manager', 'Drupal\Core\Language\LanguageManager')
+      ->addArgument(new Reference('language.default'));
+    $this->container
+      ->register('string_translation', 'Drupal\Core\StringTranslation\TranslationManager')
+      ->addArgument(new Reference('language_manager'));
+    \Drupal::setContainer($this->container);
+
     $this->drupalGet($GLOBALS['base_url'] . '/core/install.php');
 
     // Select language.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/HtmlIdentifierUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/HtmlIdentifierUnitTest.php
index ec9bbb4..3d076ce 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/HtmlIdentifierUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/HtmlIdentifierUnitTest.php
@@ -7,13 +7,12 @@
 
 namespace Drupal\system\Tests\Common;
 
-use Drupal\simpletest\UnitTestBase;
-use Symfony\Component\HttpFoundation\Request;
+use Drupal\simpletest\DrupalUnitTestBase;
 
 /**
  * Tests cleaning HTML identifiers.
  */
-class HtmlIdentifierUnitTest extends UnitTestBase {
+class HtmlIdentifierUnitTest extends DrupalUnitTestBase {
   public static function getInfo() {
     return array(
       'name' => 'HTML identifiers',
@@ -23,18 +22,6 @@ public static function getInfo() {
   }
 
   /**
-   * {@inheritdoc}
-   */
-  public function setUp() {
-    parent::setUp();
-
-    $container = \Drupal::getContainer();
-    $request = new Request();
-    $container->set('request', $request);
-    \Drupal::setContainer($container);
-  }
-
-  /**
    * Tests that drupal_clean_css_identifier() cleans the identifier properly.
    */
   function testDrupalCleanCSSIdentifier() {
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/TableSortExtenderUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/TableSortExtenderUnitTest.php
index 59eca4a..436b8a1 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/TableSortExtenderUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/TableSortExtenderUnitTest.php
@@ -7,13 +7,13 @@
 
 namespace Drupal\system\Tests\Common;
 
-use Drupal\simpletest\UnitTestBase;
+use Drupal\simpletest\DrupalUnitTestBase;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Tests unicode handling features implemented in unicode.inc.
  */
-class TableSortExtenderUnitTest extends UnitTestBase {
+class TableSortExtenderUnitTest extends DrupalUnitTestBase {
 
   public static function getInfo() {
     return array(
diff --git a/core/modules/system/lib/Drupal/system/Tests/Plugin/Discovery/DiscoveryTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Plugin/Discovery/DiscoveryTestBase.php
index 20a574a..ea02491 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Plugin/Discovery/DiscoveryTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Plugin/Discovery/DiscoveryTestBase.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\system\Tests\Plugin\Discovery;
 
-use Drupal\simpletest\UnitTestBase;
+use Drupal\simpletest\DrupalUnitTestBase;
 
 /**
  * Tests that plugins are correctly discovered.
  */
-class DiscoveryTestBase extends UnitTestBase {
+class DiscoveryTestBase extends DrupalUnitTestBase {
 
   /**
    * The discovery component to test.