Currently, I am in the process of developing an Angular application. My application is up and running with a few controllers and services. Now, my focus has shifted to starting unit testing for these services and controllers. Unfortunately, I have encountered some challenges as I am unable to properly execute a test even for a single service. Whenever I attempt to run a test using Karma by executing:
karma start karma.conf.js

An error message surfaces:

Firefox 38.0.0 (Windows 7 0.0.0) service: MyCategoryService should send a request to MyCategoryService FAILED
    minErr/<@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/bower_components/angular/angular.js:68:12
    loadModules/<@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/bower_components/angular/angular.js:4458:15
    forEach@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/bower_components/angular/angular.js:340:11
    loadModules@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/bower_components/angular/angular.js:4419:5
    createInjector@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/bower_components/angular/angular.js:4344:11
    workFn@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/js/libs/angular-mocks.js:2797:44
    angular.mock.inject@c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/js/libs/angular-mocks.js:2777:30
    @c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/js/tests/services/preferenceCategoryService.test.js:18:9
    TypeError: $httpBackend is undefined in c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/js/tests/services/preferenceCategoryServi
ce.test.js (line 33)
    @c:/Users/bgurung2/workspace/admintoolui/src/main/webapp/js/tests/services/preferenceCategoryService.test.js:33:9
Firefox 38.0.0 (Windows 7 0.0.0): Executed 13 of 13 (1 FAILED) (0.016 secs / 0.039 secs)

The source of the problem eludes me at the moment. Although I attempted to follow guidance from this StackOverflow post, I seem lost.

I would greatly appreciate any help or suggestions!

Below, you will find snippets of my app structure:

'use strict';

/* App Module */

var app = angular.module('myApp', [ 
'ngRoute', // uri routing
'controllers', // controllers
'services', // services
'ngMock'

]);

// module controllers
var appCtrl = angular.module('controllers', []);

// module services
var appServices = angular.module('services', [ 'ngResource' ]);

Here is the implementation of my service:

'use strict';

appServices.factory('MyCategoryService', ['$resource', 'REST_RESOURCE',
function ($resource, REST_RESOURCE) {
    return $resource(REST_RESOURCE.PREFERENCE, {}, {
        query: {
            method: 'GET',
            params: {},
            isArray: false
        }
    });
}]);

Now, let's examine the Service Spec:

describe('service: MyCategoryService', function () {
    var $httpBackend;
    var $rootScope;
    var MyCategoryService;
    var REST_RESOURCE;

    beforeEach(function () {
        angular.mock.module('myApp');
        angular.mock.inject(function ($injector) {
            $httpBackend = $injector.get('$httpBackend');
            $rootScope = $injector.get('$rootScope');
            MyCategoryService= $injector.get('MyCategoryService');
            REST_RESOURCE = $injector.get('REST_RESOURCE');
        });
    });

    it('should send a request to MyCategoryService', function () {
        //TODO
        var mockdata = {
            items: {
            }
        };

        $httpBackend.expect('GET', REST_RESOURCE.PREFERENCE).respond(200, mockdata);

        MyCategoryService.query(function (response) {
            $rootScope.data = response.items;
        });
        $httpBackend.flush();

        expect($rootScope.data).toEqual(mockdata);
    });

});

Lastly, here's a glance at my karma.conf.js file:

module.exports = function(config) {
  config.set({

    // base path that will be used to resolve all patterns (eg. files, exclude)
    basePath: '',


    // frameworks to use
    // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
    frameworks: ['jasmine'],


    // list of files / patterns to load in the browser
    files: [
      //dependencies
      'bower_components/angular/angular.js',
      'bower_components/angular-mocks/angular-mocks.js',
      'bower_components/angular-route/angular-route.js',
      'bower_components/angular-bootstrap/ui-bootstrap.js',
      'bower_components/angular-bootstrap/ui-bootstrap-tpls.js',
      'bower_components/angular-cookies/angular-cookies.js',
      'js/app.js',
      'js/libs/*.js',
      'js/directives/*.js',
      'js/routes.js',
      'js/resource_uri.js',
      'js/services/*.js',
      'js/controllers/*.js',
      //test files
      'js/tests/*.test.js',
      'js/tests/*/*.test.js'
    ],


    // list of files to exclude
    exclude: [
    ],


    // preprocess matching files before serving them to the browser
    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
    },


    // test results reporter to use
    // possible values: 'dots', 'progress'
    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
    reporters: ['progress'],


    // web server port
    port: 9876,


    // enable / disable colors in the output (reporters and logs)
    colors: true,


    // level of logging
    // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
    logLevel: config.LOG_INFO,

   
    autoWatch: true,

  
    browsers: ['Firefox'],

    
    singleRun: false,

   
    concurrency: Infinity
    });
};