--- /dev/null
+<?php
+
+namespace Drupal\Tests\config\Functional;
+
+use Drupal\Core\Archiver\Tar;
+use Drupal\Core\Serialization\Yaml;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests the user interface for exporting configuration.
+ *
+ * @group config
+ */
+class ConfigExportUITest extends BrowserTestBase {
+
+ /**
+ * Modules to enable.
+ *
+ * @var array
+ */
+ public static $modules = ['config', 'config_test'];
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+
+ // Set up an override.
+ $settings['config']['system.maintenance']['message'] = (object) [
+ 'value' => 'Foo',
+ 'required' => TRUE,
+ ];
+ $this->writeSettings($settings);
+
+ $this->drupalLogin($this->drupalCreateUser(['export configuration']));
+ }
+
+ /**
+ * Tests export of configuration.
+ */
+ public function testExport() {
+ // Verify the export page with export submit button is available.
+ $this->drupalGet('admin/config/development/configuration/full/export');
+ $this->assertFieldById('edit-submit', t('Export'));
+
+ // Submit the export form and verify response. This will create a file in
+ // temporary directory with the default name config.tar.gz.
+ $this->drupalPostForm('admin/config/development/configuration/full/export', [], t('Export'));
+ $this->assertResponse(200, 'User can access the download callback.');
+
+ // Test if header contains file name with hostname and timestamp.
+ $request = \Drupal::request();
+ $hostname = str_replace('.', '-', $request->getHttpHost());
+ $header_content_disposition = $this->drupalGetHeader('content-disposition');
+ $header_match = (boolean) preg_match('/attachment; filename="config-' . preg_quote($hostname) . '-\d{4}-\d{2}-\d{2}-\d{2}-\d{2}\.tar\.gz"/', $header_content_disposition);
+ $this->assertTrue($header_match, "Header with filename matches the expected format.");
+
+ // Extract the archive and verify it's not empty.
+ $file_path = file_directory_temp() . '/' . 'config.tar.gz';
+ $archiver = new Tar($file_path);
+ $archive_contents = $archiver->listContents();
+ $this->assert(!empty($archive_contents), 'Downloaded archive file is not empty.');
+
+ // Prepare the list of config files from active storage, see
+ // \Drupal\config\Controller\ConfigController::downloadExport().
+ $storage_active = $this->container->get('config.storage');
+ $config_files = [];
+ foreach ($storage_active->listAll() as $config_name) {
+ $config_files[] = $config_name . '.yml';
+ }
+ // Assert that the downloaded archive file contents are the same as the test
+ // site active store.
+ $this->assertIdentical($archive_contents, $config_files);
+
+ // Ensure the test configuration override is in effect but was not exported.
+ $this->assertIdentical(\Drupal::config('system.maintenance')->get('message'), 'Foo');
+ $archiver->extract(file_directory_temp(), ['system.maintenance.yml']);
+ $file_contents = file_get_contents(file_directory_temp() . '/' . 'system.maintenance.yml');
+ $exported = Yaml::decode($file_contents);
+ $this->assertNotIdentical($exported['message'], 'Foo');
+
+ // Check the single export form doesn't have "form-required" elements.
+ $this->drupalGet('admin/config/development/configuration/single/export');
+ $this->assertNoRaw('js-form-required form-required', 'No form required fields are found.');
+
+ // Ensure the temporary file is not available to users without the
+ // permission.
+ $this->drupalLogout();
+ $this->drupalGet('system/temporary', ['query' => ['file' => 'config.tar.gz']]);
+ $this->assertResponse(403);
+ }
+
+}