diff --git a/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php b/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
index 0dcef01615..b8236f9b3f 100644
--- a/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
+++ b/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
@@ -28,6 +28,50 @@ protected function setUp() {
     $this->root = static::getDrupalRoot();
   }
 
+  /**
+   * @coversNothing
+   */
+  public function testInstallWithNonExistingClass() {
+    $autoloader = $this->root . '/autoload.php';
+    $app = new TestInstallationSetupApplication(require $autoloader);
+    $app->setAutoExit(FALSE);
+
+    $app_tester = new ApplicationTester($app);
+    $app_tester->run(
+      [
+        'command' => 'setup-drupal-test',
+        '--setup_class' => 'this-class-does-not-exist',
+      ],
+      [
+        'interactive' => FALSE,
+      ]
+    );
+
+    $this->assertContains('There was a problem loading this-class-does-not-exist', $app_tester->getDisplay());
+  }
+
+  /**
+   * @coversNothing
+   */
+  public function testInstallWithNonSetupClass() {
+    $autoloader = $this->root . '/autoload.php';
+    $app = new TestInstallationSetupApplication(require $autoloader);
+    $app->setAutoExit(FALSE);
+
+    $app_tester = new ApplicationTester($app);
+    $app_tester->run(
+      [
+        'command' => 'setup-drupal-test',
+        '--setup_class' => static::class,
+      ],
+      [
+        'interactive' => FALSE,
+      ]
+    );
+
+    $this->assertContains('You need to define a class implementing \Drupal\Setup\TestSetupInterface ', $app_tester->getDisplay());
+  }
+
   /**
    * @coversNothing
    */
@@ -59,6 +103,17 @@ public function testInstallScript() {
     $response = $http_client->send($request);
     // Ensure the test_page_test module got installed.
     $this->assertContains('Test page | Drupal', (string) $response->getBody());
+
+    // Now test the tear down process as well.
+    $app_tester->run(
+      [
+        'command' => 'teardown-drupal-test',
+        'db_prefix' => $this->databasePrefix,
+      ],
+      [
+        'interactive' => FALSE,
+      ]
+    );
   }
 
 }
diff --git a/core/tests/Drupal/Setup/Commands/TestInstallationSetupApplication.php b/core/tests/Drupal/Setup/Commands/TestInstallationSetupApplication.php
index 9c205daf7c..f38c714ab1 100644
--- a/core/tests/Drupal/Setup/Commands/TestInstallationSetupApplication.php
+++ b/core/tests/Drupal/Setup/Commands/TestInstallationSetupApplication.php
@@ -30,13 +30,6 @@ public function __construct($autoloader) {
     parent::__construct('setup-drupal-test', '0.0.1');
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  protected function getCommandName(InputInterface $input) {
-    return 'setup-drupal-test';
-  }
-
   /**
    * {@inheritdoc}
    */
@@ -44,6 +37,7 @@ protected function getDefaultCommands() {
     // Even though this is a single command, keep the HelpCommand (--help).
     $default_commands = parent::getDefaultCommands();
     $default_commands[] = new TestInstallationSetupCommand($this->autoloader);
+    $default_commands[] = new TestTeardownCommand($this->autoloader);
     return $default_commands;
   }
 
diff --git a/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php b/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php
index 0b622a284a..325537db5e 100644
--- a/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php
+++ b/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php
@@ -59,7 +59,7 @@ protected function execute(InputInterface $input, OutputInterface $output) {
     putenv("SIMPLETEST_DB=$db_url");
     putenv("SIMPLETEST_BASE_URL=$base_url");
 
-    $this->bootstrapDrupal($this->autoloader);
+    $this->bootstrapDrupal();
 
     // Manage site fixture.
     $test = new TestInstallationSetup();
diff --git a/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php b/core/tests/Drupal/Setup/Commands/TestTeardownCommand.php
similarity index 82%
copy from core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php
copy to core/tests/Drupal/Setup/Commands/TestTeardownCommand.php
index 0b622a284a..7266207b42 100644
--- a/core/tests/Drupal/Setup/Commands/TestInstallationSetupCommand.php
+++ b/core/tests/Drupal/Setup/Commands/TestTeardownCommand.php
@@ -12,11 +12,11 @@
 use Symfony\Component\HttpFoundation\Request;
 
 /**
- * Symfony console command to setup Drupal.
+ * Tears down a test Drupal.
  *
  * @internal
  */
-class TestInstallationSetupCommand extends Command {
+class TestTeardownCommand extends Command {
 
   /**
    * The used PHP autoloader.
@@ -44,8 +44,8 @@ public function __construct($autoloader, $name = NULL) {
    * {@inheritdoc}
    */
   protected function configure() {
-    $this->setName('setup-drupal-test')
-      ->addOption('setup_class', NULL, InputOption::VALUE_OPTIONAL)
+    $this->setName('teardown-drupal-test')
+      ->addArgument('db_prefix')
       ->addOption('db_url', NULL, InputOption::VALUE_OPTIONAL, 'URL for database or SIMPLETEST_DB', getenv('SIMPLETEST_DB'))
       ->addOption('base_url', NULL, InputOption::VALUE_OPTIONAL, 'Base URL for site under test or SIMPLETEST_BASE_URL', getenv('SIMPLETEST_BASE_URL'));
   }
@@ -55,21 +55,22 @@ protected function configure() {
    */
   protected function execute(InputInterface $input, OutputInterface $output) {
     $db_url = $input->getOption('db_url');
+    $db_prefix = $input->getArgument('db_prefix');
     $base_url = $input->getOption('base_url');
     putenv("SIMPLETEST_DB=$db_url");
     putenv("SIMPLETEST_BASE_URL=$base_url");
 
-    $this->bootstrapDrupal($this->autoloader);
+    $this->bootstrapDrupal($db_prefix);
 
     // Manage site fixture.
     $test = new TestInstallationSetup();
-    $test->setup('testing', $input->getOption('setup_class'));
-
-    $output->writeln(drupal_generate_test_ua($test->getDatabasePrefix()));
+    $test->teardown($db_prefix);
   }
 
-  protected function bootstrapDrupal() {
+  protected function bootstrapDrupal($db_prefix) {
     $request = Request::createFromGlobals();
+    $_COOKIE['SIMPLETEST_USER_AGENT'] = drupal_generate_test_ua($db_prefix);
+
     $kernel = DrupalKernel::createFromRequest($request, $this->autoloader, $this->getApplication()->getName());
     DrupalKernel::bootEnvironment($kernel->getAppRoot());
 
diff --git a/core/tests/Drupal/Setup/TestInstallationSetup.php b/core/tests/Drupal/Setup/TestInstallationSetup.php
index 50b027a10a..4e816c1c06 100644
--- a/core/tests/Drupal/Setup/TestInstallationSetup.php
+++ b/core/tests/Drupal/Setup/TestInstallationSetup.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Database\Database;
 use Drupal\Core\Test\FunctionalTestSetupTrait;
+use Drupal\Core\Test\TestDatabase;
 use Drupal\Core\Test\TestSetupTrait;
 use Drupal\Tests\RandomGeneratorTrait;
 use Drupal\Tests\SessionTestTrait;
@@ -61,6 +62,43 @@ public function setup($profile = 'testing', $setup_class = NULL) {
     }
   }
 
+  /**
+   * Removes a given instance by deleting all the database tables.
+   *
+   * @param string $db_prefix
+   *   The used database prefix.
+   */
+  public function teardown($db_prefix) {
+    $tables = Database::getConnection()->schema()->findTables('%');
+    foreach ($tables as $table) {
+      if (Database::getConnection()->schema()->dropTable($table)) {
+        unset($tables[$table]);
+      }
+    }
+
+    // Delete test site directory.
+    $test_database = new TestDatabase($db_prefix);
+    file_unmanaged_delete_recursive($test_database->getTestSitePath(), [$this, 'filePreDeleteCallback']);
+  }
+
+  /**
+   * Ensures test files are deletable within file_unmanaged_delete_recursive().
+   *
+   * Some tests chmod generated files to be read only. During
+   * BrowserTestBase::cleanupEnvironment() and other cleanup operations,
+   * these files need to get deleted too.
+   *
+   * @param string $path
+   *   The file path.
+   */
+  public static function filePreDeleteCallback($path) {
+    // When the webserver runs with the same system user as phpunit, we can
+    // make read-only files writable again. If not, chmod will fail while the
+    // file deletion still works if file permissions have been configured
+    // correctly. Thus, we ignore any problems while running chmod.
+    @chmod($path, 0700);
+  }
+
   /**
    * Gets the database prefix.
    *