Function createIframeWithMessageStub

testing/iframe.js:371–423

(win)

 * @return {!HTMLIFrameElement}
 */
export function createIframeWithMessageStub(win) {
  const element = win.document.createElement('iframe');
  element.src = IFRAME_STUB_URL;

  /**
   * Instructs the iframe to send a message to parent window.
   * @param {!Object} msg
   */
  element.postMessageToParent = (msg) => {
    element.src = IFRAME_STUB_URL + encodeURIComponent(JSON.stringify(msg));
  };

  /**
   * Returns a Promise that resolves when the iframe acknowledged the reception
   * of the specified message.
   * @param {function(?Object, !Object|string)|string} callbackOrType
   *     A callback that determines if this is the message we expected. If a
   *     string is passed, the determination is based on whether the message's
   *     type matches the string.
   */
  element.expectMessageFromParent = (callbackOrType) => {
    let filter;
    if (typeof callbackOrType === 'string') {
      filter = (data) => {
        return 'type' in data && data.type == callbackOrType;
      };
    } else {
      filter = callbackOrType;
    }

    return new Promise((resolve, reject) => {
      function listener(event) {
        if (event.source != element.contentWindow || !event.data.testStubEcho) {
          return;
        }
        const message = event.data.receivedMessage;
        const data = parseIfNeeded(message);
        try {
          if (filter(data, message)) {
            win.removeEventListener('message', listener);
            resolve(data || message);
          }
        } catch (e) {
          win.removeEventListener('message', listener);
          reject(e);
        }
      }
      win.addEventListener('message', listener);
    });
  };

  return element;
}

/**
 * Returns a Promise that resolves when a post message is observed from the