--- /dev/null
+<?php
+
+namespace Drupal\system\Tests\Installer;
+
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Tests the installer when a config_directory has already been set up.
+ *
+ * @group Installer
+ */
+class InstallerExistingConfigDirectoryTest extends InstallerTestBase {
+
+ /**
+ * The expected file perms of the folder.
+ *
+ * @var int
+ */
+ protected $expectedFilePerms;
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ mkdir($this->siteDirectory . '/config_read_only', 0444);
+ $this->expectedFilePerms = fileperms($this->siteDirectory . '/config_read_only');
+ $this->settings['config_directories'][CONFIG_SYNC_DIRECTORY] = (object) [
+ 'value' => $this->siteDirectory . '/config_read_only',
+ 'required' => TRUE,
+ ];
+ parent::setUp();
+ }
+
+ /**
+ * Verifies that installation succeeded.
+ */
+ public function testInstaller() {
+ $this->assertUrl('user/1');
+ $this->assertResponse(200);
+ $this->assertEqual($this->expectedFilePerms, fileperms($this->siteDirectory . '/config_read_only'));
+ $this->assertEqual([], glob($this->siteDirectory . '/config_read_only/*'), 'The sync directory is empty after install because it is read-only.');
+ }
+
+}