HelpTopicsTestController.php

<?php

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

use Drupal\Core\Controller\ControllerBase;

/**
 * Returns the response for help_topics_test routes.
 */
class HelpTopicsTestController extends ControllerBase {
    
    /**
     * Displays a dummy page for testing.
     *
     * @param int $int_param
     *   Required parameter (ignored).
     *
     * @return array
     *   Render array for the dummy page.
     */
    public function testPage(int $int_param) {
        $build = [
            '#markup' => 'You have reached the help topics test routing page.',
        ];
        return $build;
    }

}