--- /dev/null
+<?php
+
+namespace Drupal\Tests\help\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Verifies help for experimental modules.
+ *
+ * @group help
+ */
+class ExperimentalHelpTest extends BrowserTestBase {
+
+ /**
+ * Modules to enable.
+ *
+ * The experimental_module_test module implements hook_help() and is in the
+ * Core (Experimental) package.
+ *
+ * @var array
+ */
+ public static $modules = ['help', 'experimental_module_test', 'help_page_test'];
+
+ /**
+ * The admin user.
+ *
+ * @var \Drupal\user\UserInterface
+ */
+ protected $adminUser;
+
+ /**
+ * {@inheritoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+ $this->adminUser = $this->drupalCreateUser(['access administration pages']);
+ }
+
+ /**
+ * Verifies that a warning message is displayed for experimental modules.
+ */
+ public function testExperimentalHelp() {
+ $this->drupalLogin($this->adminUser);
+ $this->drupalGet('admin/help/experimental_module_test');
+ $this->assertText('This module is experimental.');
+
+ // Regular modules should not display the message.
+ $this->drupalGet('admin/help/help_page_test');
+ $this->assertNoText('This module is experimental.');
+
+ // Ensure the actual help page is displayed to avoid a false positive.
+ $this->assertResponse(200);
+ $this->assertText('online documentation for the Help Page Test module');
+ }
+
+}