ch(eventName => {
    promise_test(() => {
      return new Promise(resolve => {
        window[`on${eventName}HandlerSetFromParserWasFired`] = resolve;
        testElement.dispatchEvent(new Event(eventName));
      });
    }, `on${eventName} handler set from parser`);

    promise_test(() => {
      const el = document.createElement("audio");
      el.setAttribute(`on${eventName}`, `window.on${eventName}HandlerSetViaSetAttributeWasFired()`);
      document.body.append(el);

      return new Promise(resolve