LocalActionTest.php

<?php

namespace Drupal\menu_test\Plugin\Derivative;

use Drupal\Component\Plugin\Derivative\DeriverBase;

/**
 * Test derivative to check local action title escaping.
 *
 * @see \Drupal\system\Tests\Menu\LocalActionTest
 */
class LocalActionTest extends DeriverBase {
    
    /**
     * {@inheritdoc}
     */
    public function getDerivativeDefinitions($base_plugin_definition) {
        $this->derivatives['example'] = $base_plugin_definition + [
            'title' => "<script>alert('Welcome to the derived jungle!')</script>",
        ];
        return $this->derivatives;
    }

}