Adds a new controlledBySW method

src/browser/sw-utils.js

@@ -208,6 +208,31 @@ class SWUtils {
     });
   }
 
+  /**
+   * <p>Register a service worker with a unique scope and
+   * create an iframe that can be controlled by that service worker, then
+   * wait until the service worker takes control.</p>
+   *
+   * <p>Useful for testing behavior that assumes the page is already controlled
+   * by a service worker.</p>
+   *
+   * @param  {String} swUrl The url to a service worker file to register
+   * @return {Promise.<HTMLElement>} Resolves with the iframe once the service
+   * worker has taken control.
+   */
+  controlledBySW(swUrl) {
+    return this.activateSW(swUrl).then(iframe => new Promise(resolve => {
+      var iframeSW = iframe.contentWindow.navigator.serviceWorker;
+      if (iframeSW.controller) {
+        resolve(iframe);
+      } else {
+        iframeSW.addEventListener('controllerchange',
+          () => resolve(iframe),
+          {once: true});
+      }
+    }));
+  }
+
   /**
    * <p>Helper method that checks a cache with a specific name exists before
    * retrieving all the cached responses inside of it.</p>

test/browser-tests/index.html

@@ -47,6 +47,7 @@
   <script src="/test/browser-tests/window-utils/get-iframe.js"></script>
   <script src="/test/browser-tests/window-utils/install-sw.js"></script>
   <script src="/test/browser-tests/window-utils/activate-sw.js"></script>
+  <script src="/test/browser-tests/window-utils/controlled-by-sw.js"></script>
   <script src="/test/browser-tests/window-utils/get-all-cached-assets.js"></script>
   <script src="/test/browser-tests/window-utils/run-sw-mocha-tests.js"></script>
 

test/browser-tests/window-utils/controlled-by-sw.js

@@ -0,0 +1,64 @@
+/*
+  Copyright 2016 Google Inc. All Rights Reserved.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+// This is a test and we want descriptions to be useful, if this
+// breaks the max-length, it's ok.
+
+/* eslint-disable max-len, no-unused-expressions */
+/* eslint-env browser, mocha */
+
+'use strict';
+
+describe('Test swUtils.controlledBySW()', function() {
+  const SERVICE_WORKER_PATH = '/test/browser-tests/window-utils/serviceworkers';
+
+  it('should reject when called with no arguments', function(done) {
+    return window.goog.swUtils.controlledBySW()
+    .then(() => done(new Error('Should have rejected')))
+    .catch(() => done());
+  });
+
+  it('should reject when called with an array argument', function(done) {
+    return window.goog.swUtils.controlledBySW([])
+    .then(() => done(new Error('Should have rejected')))
+    .catch(() => done());
+  });
+
+  it('should reject called with an object argument', function(done) {
+    return window.goog.swUtils.controlledBySW({})
+    .then(() => done(new Error('Should have rejected')))
+    .catch(() => done());
+  });
+
+  it('should reject when used with an invalid service worker path', function(done) {
+    return window.goog.swUtils.controlledBySW(SERVICE_WORKER_PATH + '/sw-doesnt-exist.js')
+    .then(() => done(new Error('Should have rejected')))
+    .catch(() => done());
+  });
+
+  it('should reject when used with a service worker that fails to install', function(done) {
+    return window.goog.swUtils.controlledBySW(SERVICE_WORKER_PATH + '/sw-broken-install.js')
+    .then(() => done(new Error('Should have rejected')))
+    .catch(() => done());
+  });
+
+  it('should resolve once the service worker controls the iframe', function() {
+    return window.goog.swUtils.controlledBySW(SERVICE_WORKER_PATH + '/immediate-control.js')
+    .then(iframe => {
+      chai.expect(iframe.contentWindow.navigator.serviceWorker.controller).to.exist;
+    });
+  });
+});

test/browser-tests/window-utils/serviceworkers/immediate-control.js

@@ -0,0 +1,2 @@
+self.addEventListener('install', () => self.skipWaiting());
+self.addEventListener('activate', () => self.clients.claim());