refactor: migrate NavigatorWatcher to lifecycle events (#1141)

This patch:
- migrates navigation watcher to use protocol-issued lifecycle events.
- removes `networkIdleTimeout` and `networkIdleInflight` options for
  `page.goto` method
- adds a new `networkidle0` value to the waitUntil option of navigation
  methods

References #728.

BREAKING CHANGE:

As an implication of this new approach, the `networkIdleTimeout` and
`networkIdleInflight` options are no longer supported. Interested
clients should implement the behavior themselves using the `request` and
`response` events.

lib/NavigatorWatcher.js

@@ -19,25 +19,28 @@ const {helper} = require('./helper');
 class NavigatorWatcher {
   /**
    * @param {!Puppeteer.Session} client
+   * @param {string} frameId
    * @param {boolean} ignoreHTTPSErrors
    * @param {!Object=} options
    */
-  constructor(client, ignoreHTTPSErrors, options = {}) {
+  constructor(client, frameId, ignoreHTTPSErrors, options = {}) {
+    console.assert(options.networkIdleTimeout === undefined, 'ERROR: networkIdleTimeout option is no longer supported.');
+    console.assert(options.networkIdleInflight === undefined, 'ERROR: networkIdleInflight option is no longer supported.');
+    console.assert(options.waitUntil !== 'networkidle', 'ERROR: "networkidle" option is no longer supported. Use "networkidle2" instead');
     this._client = client;
+    this._frameId = frameId;
     this._ignoreHTTPSErrors = ignoreHTTPSErrors;
     this._timeout = typeof options['timeout'] === 'number' ? options['timeout'] : 30000;
-    this._idleTime = typeof options['networkIdleTimeout'] === 'number' ? options['networkIdleTimeout'] : 1000;
-    this._idleInflight = typeof options['networkIdleInflight'] === 'number' ? options['networkIdleInflight'] : 2;
-    this._waitUntil = typeof options['waitUntil'] === 'string' ? options['waitUntil'] : 'load';
-    console.assert(this._waitUntil === 'load' || this._waitUntil === 'networkidle', 'Unknown value for options.waitUntil: ' + this._waitUntil);
+    const waitUntil = typeof options['waitUntil'] === 'string' ? options['waitUntil'] : 'load';
+    const isAllowedWaitUntil = waitUntil === 'networkidle0' || waitUntil === 'networkidle2' || waitUntil === 'load';
+    console.assert(isAllowedWaitUntil, 'Unknown value for options.waitUntil: ' + waitUntil);
+    this._pendingEvents = new Set([waitUntil]);
   }
 
   /**
    * @return {!Promise<?Error>}
    */
   async waitForNavigation() {
-    this._requestIds = new Set();
-
     this._eventListeners = [];
 
     const navigationPromises = [];
@@ -54,58 +57,43 @@ class NavigatorWatcher {
       navigationPromises.push(certificateError);
     }
 
-    if (this._waitUntil === 'load') {
-      const loadEventFired = new Promise(fulfill => {
-        this._eventListeners.push(helper.addEventListener(this._client, 'Page.loadEventFired', fulfill));
-      }).then(() => null);
-      navigationPromises.push(loadEventFired);
-    } else {
-      this._eventListeners.push(...[
-        helper.addEventListener(this._client, 'Network.requestWillBeSent', this._onLoadingStarted.bind(this)),
-        helper.addEventListener(this._client, 'Network.loadingFinished', this._onLoadingCompleted.bind(this)),
-        helper.addEventListener(this._client, 'Network.loadingFailed', this._onLoadingCompleted.bind(this)),
-        helper.addEventListener(this._client, 'Network.webSocketCreated', this._onLoadingStarted.bind(this)),
-        helper.addEventListener(this._client, 'Network.webSocketClosed', this._onLoadingCompleted.bind(this)),
-      ]);
-      const networkIdle = new Promise(fulfill => this._networkIdleCallback = fulfill).then(() => null);
-      navigationPromises.push(networkIdle);
-    }
+    this._eventListeners.push(helper.addEventListener(this._client, 'Page.lifecycleEvent', this._onLifecycleEvent.bind(this)));
+    const pendingEventsFired = new Promise(fulfill => this._pendingEventsCallback = fulfill);
+    navigationPromises.push(pendingEventsFired);
 
     const error = await Promise.race(navigationPromises);
     this._cleanup();
     return error ? new Error(error) : null;
   }
 
+  /**
+   * @param {!{frameId: string, name: string}} event
+   */
+  _onLifecycleEvent(event) {
+    if (event.frameId !== this._frameId)
+      return;
+    const pptrName = protocolLifecycleToPuppeteer[event.name];
+    if (!pptrName)
+      return;
+    this._pendingEvents.delete(pptrName);
+    if (this._pendingEvents.size === 0)
+      this._pendingEventsCallback();
+  }
+
   cancel() {
     this._cleanup();
   }
 
-  /**
-   * @param {!Object} event
-   */
-  _onLoadingStarted(event) {
-    this._requestIds.add(event.requestId);
-    if (this._requestIds.size > this._idleInflight) {
-      clearTimeout(this._idleTimer);
-      this._idleTimer = null;
-    }
-  }
-
-  /**
-   * @param {!Object} event
-   */
-  _onLoadingCompleted(event) {
-    this._requestIds.delete(event.requestId);
-    if (this._requestIds.size <= this._idleInflight && !this._idleTimer)
-      this._idleTimer = setTimeout(this._networkIdleCallback, this._idleTime);
-  }
-
   _cleanup() {
     helper.removeEventListeners(this._eventListeners);
-
-    clearTimeout(this._idleTimer);
     clearTimeout(this._maximumTimer);
   }
 }
 
+const protocolLifecycleToPuppeteer = {
+  'load': 'load',
+  'networkIdle': 'networkidle0',
+  'networkAlmostIdle': 'networkidle2'
+};
+
 module.exports = NavigatorWatcher;

lib/Page.js

@@ -452,7 +452,8 @@ class Page extends EventEmitter {
    * @return {!Promise<?Response>}
    */
   async goto(url, options) {
-    const watcher = new NavigatorWatcher(this._client, this._ignoreHTTPSErrors, options);
+    const mainFrame = this._frameManager.mainFrame();
+    const watcher = new NavigatorWatcher(this._client, mainFrame._id, this._ignoreHTTPSErrors, options);
     const responses = new Map();
     const listener = helper.addEventListener(this._networkManager, NetworkManager.Events.Response, response => responses.set(response.url, response));
     const navigationPromise = watcher.waitForNavigation();
@@ -492,7 +493,8 @@ class Page extends EventEmitter {
    * @return {!Promise<!Response>}
    */
   async waitForNavigation(options) {
-    const watcher = new NavigatorWatcher(this._client, this._ignoreHTTPSErrors, options);
+    const mainFrame = this._frameManager.mainFrame();
+    const watcher = new NavigatorWatcher(this._client, mainFrame._id, this._ignoreHTTPSErrors, options);
 
     const responses = new Map();
     const listener = helper.addEventListener(this._networkManager, NetworkManager.Events.Response, response => responses.set(response.url, response));