feat(page): introduce "Popup" event (#3661)

This patch adds a new "popup" event for page.
"Popup" event is fired whenever page opens another page with
given opener.

docs/api.md

@@ -79,6 +79,7 @@
   * [event: 'load'](#event-load)
   * [event: 'metrics'](#event-metrics)
   * [event: 'pageerror'](#event-pageerror)
+  * [event: 'popup'](#event-popup)
   * [event: 'request'](#event-request)
   * [event: 'requestfailed'](#event-requestfailed)
   * [event: 'requestfinished'](#event-requestfinished)
@@ -963,6 +964,25 @@ of metrics see `page.metrics`.
 
 Emitted when an uncaught exception happens within the page.
 
+#### event: 'popup'
+- <[Page]> Page corresponding to "popup" window
+
+Emitted when the page opens a new tab or window.
+
+```js
+const [popup] = await Promise.all([
+  new Promise(resolve => page.once('popup', resolve)),
+  page.click('a[target=_blank]'),
+]);
+```
+
+```js
+const [popup] = await Promise.all([
+  new Promise(resolve => page.once('popup', resolve)),
+  page.evaluate(() => window.open('https://example.com')),
+]);
+```
+
 #### event: 'request'
 - <[Request]>
 

lib/Page.js

@@ -1192,6 +1192,7 @@ Page.Events = {
   FrameNavigated: 'framenavigated',
   Load: 'load',
   Metrics: 'metrics',
+  Popup: 'popup',
   WorkerCreated: 'workercreated',
   WorkerDestroyed: 'workerdestroyed',
 };

lib/Target.js

@@ -20,7 +20,19 @@ class Target {
     this._screenshotTaskQueue = screenshotTaskQueue;
     /** @type {?Promise<!Puppeteer.Page>} */
     this._pagePromise = null;
-    this._initializedPromise = new Promise(fulfill => this._initializedCallback = fulfill);
+    this._initializedPromise = new Promise(fulfill => this._initializedCallback = fulfill).then(async success => {
+      if (!success)
+        return false;
+      const opener = this.opener();
+      if (!opener || !opener._pagePromise || this.type() !== 'page')
+        return true;
+      const openerPage = await opener._pagePromise;
+      if (!openerPage.listenerCount(Page.Events.Popup))
+        return true;
+      const popupPage = await this.page();
+      openerPage.emit(Page.Events.Popup, popupPage);
+      return true;
+    });
     this._isClosedPromise = new Promise(fulfill => this._closedCallback = fulfill);
     this._isInitialized = this._targetInfo.type !== 'page' || this._targetInfo.url !== '';
     if (this._isInitialized)

test/page.spec.js

@@ -93,6 +93,55 @@ module.exports.addTests = function({testRunner, expect, headless}) {
     });
   });
 
+  describe('Page.Events.Popup', function() {
+    it('should work', async({page}) => {
+      const [popup] = await Promise.all([
+        new Promise(x => page.once('popup', x)),
+        page.evaluate(() => window.open('about:blank')),
+      ]);
+      expect(await page.evaluate(() => !!window.opener)).toBe(false);
+      expect(await popup.evaluate(() => !!window.opener)).toBe(true);
+    });
+    it('should work with noopener', async({page}) => {
+      const [popup] = await Promise.all([
+        new Promise(x => page.once('popup', x)),
+        page.evaluate(() => window.open('about:blank', null, 'noopener')),
+      ]);
+      expect(await page.evaluate(() => !!window.opener)).toBe(false);
+      expect(await popup.evaluate(() => !!window.opener)).toBe(false);
+    });
+    it('should work with clicking target=_blank', async({page, server}) => {
+      await page.goto(server.EMPTY_PAGE);
+      await page.setContent('<a target=_blank href="/one-style.html">yo</a>');
+      const [popup] = await Promise.all([
+        new Promise(x => page.once('popup', x)),
+        page.click('a'),
+      ]);
+      expect(await page.evaluate(() => !!window.opener)).toBe(false);
+      expect(await popup.evaluate(() => !!window.opener)).toBe(true);
+    });
+    it('should work with fake-clicking target=_blank and rel=noopener', async({page, server}) => {
+      await page.goto(server.EMPTY_PAGE);
+      await page.setContent('<a target=_blank rel=noopener href="/one-style.html">yo</a>');
+      const [popup] = await Promise.all([
+        new Promise(x => page.once('popup', x)),
+        page.$eval('a', a => a.click()),
+      ]);
+      expect(await page.evaluate(() => !!window.opener)).toBe(false);
+      expect(await popup.evaluate(() => !!window.opener)).toBe(false);
+    });
+    it('should work with clicking target=_blank and rel=noopener', async({page, server}) => {
+      await page.goto(server.EMPTY_PAGE);
+      await page.setContent('<a target=_blank rel=noopener href="/one-style.html">yo</a>');
+      const [popup] = await Promise.all([
+        new Promise(x => page.once('popup', x)),
+        page.click('a'),
+      ]);
+      expect(await page.evaluate(() => !!window.opener)).toBe(false);
+      expect(await popup.evaluate(() => !!window.opener)).toBe(false);
+    });
+  });
+
   describe('BrowserContext.overridePermissions', function() {
     function getPermission(page, name) {
       return page.evaluate(name => navigator.permissions.query({name}).then(result => result.state), name);