[MD settings] settings toggle control browser test addtion

chrome/test/data/webui/settings/settings_toggle_button_tests.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** @fileoverview Suite of tests for settings-toggle-button. */
 cr.define('settings_toggle_button', function() {
   function registerTests() {
     suite('SettingsToggleButton', function() {
       /**
        * Toggle button created before each test.
        * @type {SettingsCheckbox}
        */
       var testElement;
 
-      /**
-       * Pref value used in tests, should reflect the 'checked' attribute.
-       * @type {SettingsCheckbox}
-       */
-      var pref = {
-        key: 'test',
-        type: chrome.settingsPrivate.PrefType.BOOLEAN,
-        value: true
-      };
-
       // Initialize a checked control before each test.
       setup(function() {
+        /**
+         * Pref value used in tests, should reflect the 'checked' attribute.
+         * Create a new pref for each test() to prevent order (state)
+         * dependencies between tests.
+         * @type {chrome.settingsPrivate.PrefObject}
+         */
+        var pref = {
+          key: 'test',
+          type: chrome.settingsPrivate.PrefType.BOOLEAN,
+          value: true
+        };
         PolymerTest.clearBody();
         testElement = document.createElement('settings-toggle-button');
         testElement.set('pref', pref);
         document.body.appendChild(testElement);
       });
 
       test('responds to checked attribute', function() {
         assertTrue(testElement.checked);
 
         testElement.removeAttribute('checked');
         assertFalse(testElement.checked);
-        assertFalse(pref.value);
+        assertFalse(testElement.pref.value);
 
         testElement.setAttribute('checked', '');
         assertTrue(testElement.checked);
-        assertTrue(pref.value);
+        assertTrue(testElement.pref.value);
+      });
+
+      test('value changes on tap', function() {
+        assertTrue(testElement.checked);
+        assertTrue(testElement.pref.value);
+
+        MockInteractions.tap(testElement.$.control);
+        assertFalse(testElement.checked);
+        assertFalse(testElement.pref.value);
+
+        MockInteractions.tap(testElement.$.control);
+        assertTrue(testElement.checked);
+        assertTrue(testElement.pref.value);
       });
 
       test('fires a change event', function(done) {
         testElement.addEventListener('change', function() {
           assertFalse(testElement.checked);
           done();
         });
+        assertTrue(testElement.checked);
         MockInteractions.tap(testElement.$.control);
       });
 
       test('does not change when disabled', function() {
         testElement.checked = false;
         testElement.setAttribute('disabled', '');
         assertTrue(testElement.disabled);
         assertTrue(testElement.$.control.disabled);
 
         MockInteractions.tap(testElement.$.control);
@@ skipping 19 matching lines @@
         assertTrue(testElement.checked);
         assertEquals(1, prefNum.value);
       });
     });
   }
 
   return {
     registerTests: registerTests,
   };
 });