diff --git a/core/modules/system/src/Tests/Installer/InstallerTranslationMultipleLanguageTest.php b/core/modules/system/src/Tests/Installer/InstallerTranslationMultipleLanguageTest.php
index ec8803e..c1180bf 100644
--- a/core/modules/system/src/Tests/Installer/InstallerTranslationMultipleLanguageTest.php
+++ b/core/modules/system/src/Tests/Installer/InstallerTranslationMultipleLanguageTest.php
@@ -124,6 +124,12 @@ public function testTranslationsLoaded() {
     }
     else {
       $this->assertTrue($override_en->isNew());
+
+      // Assert that adding English makes the English override available.
+      $edit = ['predefined_langcode' => 'en'];
+      $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
+      $override_en = $language_manager->getLanguageConfigOverride('en', 'user.settings');
+      $this->assertEqual($override_en->get('anonymous'), 'Anonymous');
     }
   }
 
diff --git a/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php b/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
index 8d9305c..f68ccf8 100644
--- a/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
+++ b/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
@@ -11,8 +11,7 @@
 use Drupal\user\Entity\User;
 
 /**
- * Selects German as the installation language and verifies the following page
- * is not in English.
+ * Installs Drupal in German and checks resulting site.
  *
  * @group Installer
  */
@@ -31,14 +30,15 @@ class InstallerTranslationTest extends InstallerTestBase {
   protected function setUpLanguage() {
     // Place a custom local translation in the translations directory.
     mkdir(\Drupal::root() . '/' . $this->siteDirectory . '/files/translations', 0777, TRUE);
-    file_put_contents(\Drupal::root() . '/' . $this->siteDirectory . '/files/translations/drupal-8.0.0.de.po', "msgid \"\"\nmsgstr \"\"\nmsgid \"Save and continue\"\nmsgstr \"Save and continue German\"");
+    file_put_contents(\Drupal::root() . '/' . $this->siteDirectory . '/files/translations/drupal-8.0.0.de.po', $this->getPo('de'));
 
     parent::setUpLanguage();
+
     // After selecting a different language than English, all following screens
     // should be translated already.
     $elements = $this->xpath('//input[@type="submit"]/@value');
-    $this->assertEqual((string) current($elements), 'Save and continue German');
-    $this->translations['Save and continue'] = 'Save and continue German';
+    $this->assertEqual((string) current($elements), 'Save and continue de');
+    $this->translations['Save and continue'] = 'Save and continue de';
 
     // Check the language direction.
     $direction = (string) current($this->xpath('/html/@dir'));
@@ -46,12 +46,18 @@ protected function setUpLanguage() {
   }
 
   /**
-   * Verifies that installation succeeded.
+   * Verifies the expected behaviors of the installation result.
    */
   public function testInstaller() {
     $this->assertUrl('user/1');
     $this->assertResponse(200);
 
+    // Verify German was configured but not English.
+    $this->drupalGet('admin/config/regional/language');
+    $this->assertText('German');
+    $this->assertNoText('English');
+
+    /** @var \Drupal\user\Entity\User $account */
     $account = User::load(0);
     $this->assertEqual($account->language()->getId(), 'en', 'Anonymous user is English.');
     $account = User::load(1);
@@ -68,6 +74,57 @@ public function testInstaller() {
     $this->drupalPostForm('admin/config/development/performance', $edit, t('Save configuration'));
     $this->drupalGet('<front>');
     $this->assertRaw('classy/css/layout.css');
+
+    // Verify the strings from the translation files were imported.
+    $test_samples = ['Save and continue', 'Anonymous'];
+    foreach($test_samples as $sample) {
+      $edit = array();
+      $edit['langcode'] = 'de';
+      $edit['translation'] = 'translated';
+      $edit['string'] = $sample;
+      $this->drupalPostForm('admin/config/regional/translate', $edit, t('Filter'));
+      $this->assertText($sample . ' de');
+    }
+
+    /** @var \Drupal\language\ConfigurableLanguageManager $language_manager */
+    $language_manager = \Drupal::languageManager();
+
+    // Installed in German, configuration should be in German. No German or
+    // English overrides should be present.
+    $config = \Drupal::config('user.settings');
+    $override_de = $language_manager->getLanguageConfigOverride('de', 'user.settings');
+    $override_en = $language_manager->getLanguageConfigOverride('en', 'user.settings');
+    $this->assertEqual($config->get('anonymous'), 'Anonymous de');
+    $this->assertEqual($config->get('langcode'), 'de');
+    $this->assertTrue($override_de->isNew());
+    $this->assertTrue($override_en->isNew());
+
+    // Assert that adding English makes the English override available.
+    $edit = ['predefined_langcode' => 'en'];
+    $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
+    $override_en = $language_manager->getLanguageConfigOverride('en', 'user.settings');
+    $this->assertEqual($override_en->get('anonymous'), 'Anonymous');
+  }
+
+  /**
+   * Returns the string for the test .po file.
+   *
+   * @param string $langcode
+   *   The language code.
+   * @return string
+   *   Contents for the test .po file.
+   */
+  protected function getPo($langcode) {
+    return <<<ENDPO
+msgid ""
+msgstr ""
+
+msgid "Save and continue"
+msgstr "Save and continue $langcode"
+
+msgid "Anonymous"
+msgstr "Anonymous $langcode"
+ENDPO;
   }
 
 }