feat(browser): Add browser.isConnected() (#4403)

Add `browser.isConnected()` to the public api to be able to tell when the browser is connected

fixes https://github.com/smooth-code/jest-puppeteer/pull/237#issuecomment-490260041

docs/api.md

@@ -48,6 +48,7 @@
   * [browser.createIncognitoBrowserContext()](#browsercreateincognitobrowsercontext)
   * [browser.defaultBrowserContext()](#browserdefaultbrowsercontext)
   * [browser.disconnect()](#browserdisconnect)
+  * [browser.isConnected()](#browserisconnected)
   * [browser.newPage()](#browsernewpage)
   * [browser.pages()](#browserpages)
   * [browser.process()](#browserprocess)
@@ -700,6 +701,12 @@ Returns the default browser context. The default browser context can not be clos
 
 Disconnects Puppeteer from the browser, but leaves the Chromium process running. After calling `disconnect`, the [Browser] object is considered disposed and cannot be used anymore.
 
+#### browser.isConnected()
+
+- returns: <[boolean]>
+
+Indicates that the browser is connected.
+
 #### browser.newPage()
 - returns: <[Promise]<[Page]>>
 

experimental/puppeteer-firefox/lib/Browser.js

@@ -57,6 +57,13 @@ class Browser extends EventEmitter {
     this._connection.dispose();
   }
 
+  /**
+   * @return {boolean}
+   */
+  isConnected() {
+    return !this._connection._closed;
+  }
+
   /**
    * @return {!BrowserContext}
    */

lib/Browser.js

@@ -260,6 +260,13 @@ class Browser extends EventEmitter {
     this._connection.dispose();
   }
 
+  /**
+   * @return {boolean}
+   */
+  isConnected() {
+    return !this._connection._closed;
+  }
+
   /**
    * @return {!Promise<!Object>}
    */

test/browser.spec.js

@@ -60,4 +60,14 @@ module.exports.addTests = function({testRunner, expect, headless, puppeteer, CHR
       await remoteBrowser.disconnect();
     });
   });
+
+  describe('Browser.isConnected', () => {
+    it('should set the browser connected state', async({browser}) => {
+      const browserWSEndpoint = browser.wsEndpoint();
+      const newBrowser = await puppeteer.connect({browserWSEndpoint});
+      expect(newBrowser.isConnected()).toBe(true);
+      await newBrowser.disconnect();
+      expect(newBrowser.isConnected()).toBe(false);
+    });
+  });
 };