[MD settings] scroll to section find host

chrome/test/data/webui/settings/basic_page_browsertest.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 the Settings basic page. */
 
 GEN_INCLUDE(['settings_page_browsertest.js']);
 
 /**
  * @constructor
  * @extends {SettingsPageBrowserTest}
 */
 function SettingsBasicPageBrowserTest() {}
 
 SettingsBasicPageBrowserTest.prototype = {
   __proto__: SettingsPageBrowserTest.prototype
 };
 
 // Times out on debug builders and may time out on memory bots because
 // the Settings page can take several seconds to load in a Release build
 // and several times that in a Debug build. See https://crbug.com/558434.
 GEN('#if defined(MEMORY_SANITIZER) || !defined(NDEBUG)');
 GEN('#define MAYBE_Load DISABLED_Load');
 GEN('#else');
 GEN('#define MAYBE_Load Load');
 GEN('#endif');
 
 TEST_F('SettingsBasicPageBrowserTest', 'MAYBE_Load', function() {

[michaelpg, 2016/06/06 20:13:04]

Load is no longer an appropriate name for this test.

   // Assign |self| to |this| instead of binding since 'this' in suite()
   // and test() will be a Mocha 'Suite' or 'Test' instance.
   var self = this;
 
   // Register mocha tests.
   suite('SettingsPage', function() {
     test('load page', function() {
       // This will fail if there are any asserts or errors in the Settings page.
     });
 
     test('basic pages', function() {
       var page = self.getPage('basic');
       var sections = ['appearance', 'onStartup', 'people', 'search'];
       expectTrue(!!self.getSection(page, 'appearance'));
       if (!cr.isChromeOS)
         sections.push('defaultBrowser');
       else
         sections = sections.concat(['internet', 'device']);
 
       for (var i = 0; i < sections.length; i++) {
         var section = self.getSection(page, sections[i]);
         expectTrue(!!section);
         self.verifySubpagesHidden(section);
       }
     });
+
+    // This test checks for a regression that occurred with scrollToSection_
+    // failing to find its host element.
+    test('scroll to section', function() {
+      // Setting the page and section will cause a scrollToSection_.
+      self.getPage('basic').currentRoute = {

[michaelpg, 2016/06/06 20:13:03]

Since this is a test of the entire page, why not trigger the actual interaction
being tested (tapping an item in the settings-menu)?

+        page: 'basic',
+        section: 'onStartup',
+        subpage: [],
+      };
+
+      return new Promise(function(resolve, reject) {
+        var intervalId = window.setInterval(function() {
+          var page = self.getPage('basic');
+          if (self.getSection(page, page.currentRoute.section)) {

[michaelpg, 2016/06/06 20:13:04]

Why not actually *check* page.scroller.scrollTop to confirm the page has
scrolled?

+            window.clearInterval(intervalId);
+            resolve();
+          }
+        }, 55);

[michaelpg, 2016/06/06 20:13:03]

This is an unnecessary use of setInterval when setTimeout with a 0 timeout would
suffice.

+      }.bind(self));
+    });
   });
 
   // Run all registered tests.
   mocha.run();
 });