--- /dev/null
+<?php
+
+namespace Drupal\FunctionalTests\Installer;
+
+/**
+ * Tests the installer with an existing Drupal installation.
+ *
+ * @group Installer
+ */
+class InstallerExistingInstallationTest extends InstallerTestBase {
+
+ /**
+ * Verifies that Drupal can't be reinstalled while an existing installation is
+ * available.
+ */
+ public function testInstaller() {
+ // Verify that Drupal can't be immediately reinstalled.
+ $this->visitInstaller();
+ $this->assertRaw('Drupal already installed');
+
+ // Delete settings.php and attempt to reinstall again.
+ unlink($this->siteDirectory . '/settings.php');
+ $this->visitInstaller();
+ $this->setUpLanguage();
+ $this->setUpProfile();
+ $this->setUpRequirementsProblem();
+ $this->setUpSettings();
+ $this->assertRaw('Drupal already installed');
+ }
+
+}