Adding first unit tests with mocks

chrome/browser/resources/google_now/background_test_util.js

 // Copyright 2013 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.
 
 // Mocks for globals needed for loading background.js.
 
 function emptyMock() {}
 function buildTaskManager() {
   return {instrumentApiFunction: emptyMock};
 }
 var instrumentApiFunction = emptyMock;
 var buildAttemptManager = emptyMock;
 var emptyListener = {addListener: emptyMock};
 chrome['location'] = {onLocationUpdate: emptyListener};
 chrome['notifications'] = {
   onButtonClicked: emptyListener,
   onClicked: emptyListener,
   onClosed: emptyListener
 };
 chrome['omnibox'] = {onInputEntered: emptyListener};
 chrome['runtime'] = {
   onInstalled: emptyListener,
   onStartup: emptyListener
 };
+
 var storage = {};
+
+/**
+ * Syntactic sugar for use with will() on a Mock4JS.Mock.
+ * Creates an action for will() that invokes a callback that the tested code
+ * passes to a mocked function.
+ * @param {SaveMockArguments} savedArgs Arguments that will contain the
+ *     callback once the mocked function is called.
+ * @param {number} callbackParameter Index of the callback parameter in
+ *     |savedArgs|.
+ * @param {...Object} var_args Arguments to pass to the callback.
+ * @return {CallFunctionAction} Action for use in will().
+ */
+function invokeCallback(savedArgs, callbackParameter, var_args) {
+  var callbackArguments = Array.prototype.slice.call(arguments, 2);
+  return callFunction(function() {
+    savedArgs.arguments[callbackParameter].apply(null, callbackArguments);
+  });
+}
+
+/**
+  * Mock4JS matcher object that matches the actual agrument and the expected
+  * value iff their JSON represenations are same.
+  * @param {Object} expectedValue Expected value.
+  * @constructor
+  */
+function MatchJSON(expectedValue) {
+  this.expectedValue_ = expectedValue;
+}
+
+MatchJSON.prototype = {
+  /**
+    * Checks that JSON represenation of the actual and expected arguments are
+    * same.
+    * @param {Object} actualArgument The argument to match.
+    * @return {boolean} Result of the comparison.
+    */
+  argumentMatches: function(actualArgument) {
+    return (

[arv (Not doing code reviews), 2013/07/12 14:18:34]

Or

    return JSON.stringify(this.expectedValue_) ===
        JSON.stringify(actualArgument);

[vadimt, 2013/07/12 18:22:35]

Done.

+      JSON.stringify(this.expectedValue_) === JSON.stringify(actualArgument));
+  },
+
+  /**
+    * Describes the matcher.
+    * @return {string} Description of this Mock4JS matcher.
+    */
+  describe: function() {
+    return 'eqJSON(' + JSON.stringify(this.expectedValue_) + ')';
+  }
+};
+
+/**
+  * Builds a MatchJSON agrument matcher for a given expected value.
+  * @param {Object} expectedValue Expected value.
+  * @return {MatchJSON} Resulting Mock4JS matcher.
+  */
+function eqJSON(expectedValue) {
+  return new MatchJSON(expectedValue);
+}