TestController.php

<?php

declare (strict_types=1);
namespace Drupal\csrf_test\Controller;

use Symfony\Component\HttpFoundation\Response;

/**
 * Just a test controller for test routes.
 */
class TestController {
    
    /**
     * Just a test method for the test routes.
     *
     * @return \Symfony\Component\HttpFoundation\Response
     *   The response object.
     */
    public function testMethod() {
        return new Response('Sometimes it is hard to think of test content!');
    }

}