return array(
    '#theme' => 'testing_block',
    '#testBlockData' => $testBlockData,
    '#cache' => array(
        'contexts' => array('url.path'),
    ),
);

return array(
    '#theme' => 'testing_block',
    '#testBlockData' => $testBlockData,
    '#cache' => array(
        'max-age' => 0,
    ),
);

return array(
    '#theme' => 'testing_block',
    '#testBlockData' => $testBlockData,
    '#cache' => array(
        'contexts' => array('url.path'),
        'max-age' => 0,
    ),
);

Drupal::service('page_cache_kill_switch')->trigger();

/**
   * {@inheritdoc}
   */
  public function getCacheMaxAge() {
    return 0;
  }