MD Settings: Checks the event target in the language tap event handler

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

 // Copyright 2016 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-languages-page. */
 
 /** @const {string} Path to root from chrome/test/data/webui/settings/. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 36 matching lines @@
 
 // Runs languages page tests.
 TEST_F('SettingsLanguagesPageBrowserTest', 'MAYBE_LanguagesPage', function() {
   suite('languages page', function() {
     testing.Test.disableAnimationsAndTransitions();
 
     var advanced = this.getPage('advanced');
 
     var languagesSection;
     var languagesPage;
+    var languageHelper;
     suiteSetup(function() {
       advanced.set('pageVisibility.languages', true);
       Polymer.dom.flush();
 
       languagesSection = this.getSection(advanced, 'languages');
       assertTrue(!!languagesSection);
       languagesPage = languagesSection.querySelector('settings-languages-page');
       assertTrue(!!languagesPage);
 
-      return LanguageHelperImpl.getInstance().whenReady();
+      languageHelper = LanguageHelperImpl.getInstance();
+      return languageHelper.whenReady();
     }.bind(this));
 
     teardown(function(done) {
       // Close the section if we're in a sub-page.
       if (settings.getCurrentRoute().isSubpage()) {
         settings.navigateTo(settings.Route.ADVANCED);
         setTimeout(done);
       } else {
         done();
       }
     });
 
     test('manage languages', function() {
       var manageLanguagesButton =
           languagesPage.$.languagesCollapse.querySelector(
               '.list-button:last-of-type');
       MockInteractions.tap(manageLanguagesButton);
       assertTrue(!!languagesPage.$$('settings-manage-languages-page'));
     });
 
+    test('Should not set UI language', function() {
+      var languagesCollapse = languagesPage.$.languagesCollapse;
+      var languageOptionsDropdownTrigger = languagesCollapse.querySelector(
+          'paper-icon-button');
+      assertTrue(!!languageOptionsDropdownTrigger);
+
+      // This shouldn't get called.
+      languageHelper.setUILanguage = assertNotReached;
+
+      MockInteractions.tap(languageOptionsDropdownTrigger);
+    });
+
     test('language detail', function() {
       var languagesCollapse = languagesPage.$.languagesCollapse;
       var languageDetailMenuItem = languagesCollapse.querySelectorAll(
           '.dropdown-content .dropdown-item')[2];
       assertTrue(!!languageDetailMenuItem);
       MockInteractions.tap(languageDetailMenuItem);
 
       var languageDetailPage =
           languagesPage.$$('settings-language-detail-page');
       assertTrue(!!languageDetailPage);
@@ skipping 26 matching lines @@
         assertTrue(!!languagesPage.$$('settings-edit-dictionary-page'));
       }
     });
   }.bind(this));
 
   // TODO(michaelpg): Test more aspects of the languages UI.
 
   // Run all registered tests.
   mocha.run();
 });