diff -u b/core/lib/Drupal/Core/Database/Install/Tasks.php b/core/lib/Drupal/Core/Database/Install/Tasks.php
--- b/core/lib/Drupal/Core/Database/Install/Tasks.php
+++ b/core/lib/Drupal/Core/Database/Install/Tasks.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Database\Install;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Database\Database;
 
 /**
reverted:
--- b/core/modules/system/src/Tests/Installer/InstallerNotValidDatabaseSettingsTest.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\system\Tests\Installer\InstallerNotValidDatabaseSettingsTest.
- */
-
-namespace Drupal\system\Tests\Installer;
-
-use Drupal\Core\Database\Database;
-use Drupal\simpletest\InstallerTestBase;
-
-/**
- * Tests the installer with an existing settings file with database connection
- * info.
- *
- * @group Installer
- */
-class InstallerNotValidDatabaseSettingsTest extends InstallerTestBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    // Pre-configure database credentials in settings.php.
-    $connection_info = Database::getConnectionInfo();
-    unset($connection_info['default']['pdo']);
-    unset($connection_info['default']['init_commands']);
-
-    $this->settings['databases']['default'] = (object) array(
-      'value' => $connection_info,
-      'required' => TRUE,
-    );
-    parent::setUp();
-  }
-
-  /**
-   * For testing database failures.
-   */
-  protected function setupSettings() {
-    // All database settings should be pre-configured, except password.
-    $values = $this->parameters['forms']['install_settings_form'];
-    $driver = $values['driver'];
-    $edit = array();
-    $edit = $this->translatePostValues(array(
-      $driver => array(
-        'password' => $this->randomMachineName(),
-      ),
-    ));
-    $this->drupalPostForm(NULL, $edit, $this->translations['Save and continue']);
-  }
-
-}
only in patch2:
unchanged:
--- a/core/modules/simpletest/src/InstallerTestBase.php
+++ b/core/modules/simpletest/src/InstallerTestBase.php
@@ -72,6 +72,13 @@
   protected $isInstalled = FALSE;
 
   /**
+   * Whether to bail right after configuring the settings in the installer.
+   *
+   * @var bool
+   */
+  protected $testSetUpSettingsOnly = FALSE;
+
+  /**
    * Overrides WebTestBase::setUp().
    */
   protected function setUp() {
@@ -131,6 +138,9 @@ protected function setUp() {
 
     // Configure settings.
     $this->setUpSettings();
+    if ($this->testSetUpSettingsOnly === TRUE) {
+      return;
+    }
 
     // @todo Allow test classes based on this class to act on further installer
     //   screens.