MD Settings: Use a browser proxy from the languages page. Re-enable test.

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

Index: chrome/test/data/webui/settings/languages_tests.js
diff --git a/chrome/test/data/webui/settings/languages_tests.js b/chrome/test/data/webui/settings/languages_tests.js
index 7d6f583311f7a1ec97693c1f27466a8741f66c31..cb97715a248d212b2cd609f6ed9e3a0ddf01a558 100644
--- a/chrome/test/data/webui/settings/languages_tests.js
+++ b/chrome/test/data/webui/settings/languages_tests.js
@@ -4,6 +4,55 @@
 
 cr.define('settings-languages', function() {
   /**
+   * @constructor
+   * @implements {settings.LanguagesBrowserProxy}
+   * @extends {settings.TestBrowserProxy}
+   */
+  var TestLanguagesBrowserProxy = function() {
+    var methodNames = [];
+    if (cr.isChromeOS || cr.isWindows)
+      methodNames.push('getProspectiveUILanguage');
+
+    settings.TestBrowserProxy.call(this, methodNames);
+
+    this.languageSettingsPrivate_ = null;

[Dan Beam, 2017/04/19 17:46:52]

this.languageSettingsPrivate_ = new settings.FakeLanguageSettingsPrivate;

[dpapad, 2017/04/19 18:11:30]

See related last comment in this file.

+    this.inputMethodPrivate_ = null;
+  };
+
+  TestLanguagesBrowserProxy.prototype = {
+    __proto__: settings.TestBrowserProxy.prototype,
+
+    /** @override */
+    getLanguageSettingsPrivate: function() {
+      return this.languageSettingsPrivate_;
+    },
+
+    /** @param {!LanguagesSettingsPrivate} private */
+    setLanguageSettingsPrivate: function(private) {
+      this.languageSettingsPrivate_ = private;

[Dan Beam, 2017/04/19 17:46:52]

i would not recommend private as a var name

[dpapad, 2017/04/19 18:11:30]

Done.

+    },
+
+    /** @override */
+    getInputMethodPrivate: function() {
+      return this.inputMethodPrivate_;
+    },
+
+    /** @param {!LanguagesSettingsPrivate} private */
+    setInputMethodPrivate: function(private) {
+      this.inputMethodPrivate_ = private;
+    },
+  };
+
+  if (cr.isChromeOS || cr.isWindows) {
+    /** @override */
+    TestLanguagesBrowserProxy.prototype.getProspectiveUILanguage =
+        function() {
+      this.methodCalled('getProspectiveUILanguage');
+      return Promise.resolve('en-US');
+    };
+  }
+
+  /**
    * Data-binds two Polymer properties using the property-changed events and
    * set/notifyPath API. Useful for testing components which would normally be
    * used together.
@@ -74,8 +123,10 @@ cr.define('settings-languages', function() {
       }
     }
 
+    /** @type {?settings.LanguagesBrowserProxy} */
+    var browserProxy = null;
+
     var languageHelper;
-    var languageSettingsPrivate;
 
     suiteSetup(function() {
       CrSettingsPrefs.deferInitialization = true;
@@ -88,17 +139,17 @@ cr.define('settings-languages', function() {
       settingsPrefs.initialize(settingsPrivate);
       document.body.appendChild(settingsPrefs);
 
-      languageSettingsPrivate = new settings.FakeLanguageSettingsPrivate();
+      // Setup test browser proxy.
+      browserProxy = new TestLanguagesBrowserProxy();
+      settings.LanguagesBrowserProxyImpl.instance_ = browserProxy;
+
+      // Setup fake languageSettingsPrivate API.
+      var languageSettingsPrivate = new settings.FakeLanguageSettingsPrivate();

[Dan Beam, 2017/04/19 17:46:52]

why not just instantiate these directly in TestLanguageBrowserProxy's
constructor?

[dpapad, 2017/04/19 18:11:30]

The next line calls setSettingsPrefs() which is a method only existing on
FakeLanguageSettingsPrivate, but not on the interface LanguageSettingsPrivate
returned by LanguagesBrowserProxy. So technically I think this is more correct.
In practice it does not matter, because we don't currently type check our tests.

Besides type checking, from a design point of view, a test browser proxy is
meant to be a super thin object that does no work in its constructor. Clients of
the test proxy are supposed to configure the proxy by calling set*() methods on
it, in order to force a certain response.

[Dan Beam, 2017/04/19 18:31:55]

i don't see that as a requirement, and am likely not to do this when it
complicates the code

       languageSettingsPrivate.setSettingsPrefs(settingsPrefs);
-      settings.languageSettingsPrivateApiForTest = languageSettingsPrivate;
+      browserProxy.setLanguageSettingsPrivate(languageSettingsPrivate);
 
-      var getProspectiveUILanguageCalled = false;
-      registerMessageCallback('getProspectiveUILanguage', null,
-          function(callbackId) {
-            assertFalse(getProspectiveUILanguageCalled);
-            getProspectiveUILanguageCalled = true;
-            cr.webUIResponse(callbackId, true, 'en-US');
-          });
+      // Setup fake inputMethodPrivate API.
+      browserProxy.setInputMethodPrivate(new settings.FakeInputMethodPrivate());
 
       languageHelper = document.createElement('settings-languages');
 
@@ -107,12 +158,13 @@ cr.define('settings-languages', function() {
 
       document.body.appendChild(languageHelper);
       return languageHelper.whenReady().then(function() {
-        assertEquals(
-            cr.isChromeOS || cr.isWindows, getProspectiveUILanguageCalled);
+        if (cr.isChromeOS || cr.isWindows)
+          return browserProxy.whenCalled('getProspectiveUILanguage');
       });
     });
 
     test('languages model', function() {
+      var languageSettingsPrivate = browserProxy.getLanguageSettingsPrivate();
       for (var i = 0; i < languageSettingsPrivate.languages.length;
            i++) {
         assertEquals(languageSettingsPrivate.languages[i].code,