Testing with Jasmine an AngularJS factory method that returns a $timeout promise

(function() {
  'use strict';
  
  angular.module('MyApp', []);

  angular.module('MyApp')
    .constant("ROUTES", {
      get: "real-get-path"
    });
  
  angular.module('MyApp')
    .factory('MyFactory', ['$http', '$timeout', 'ROUTES', MyFactory]);
    
  function MyFactory($http, $timeout, ROUTES) {
    return {
      myGet: function(id) {
        var random = Math.random() * 1000;
        return $timeout(function () {
            return $http.get(ROUTES.get, {
              params: { id: id }
            })
              .then(function(response) {
                return response.data;
              });
        }, random);
      }
    };
  }
})();

<!DOCTYPE html>
<html ng-app="MyApp">
  <head>
    <meta charset="utf-8" />
    <title>Jasmine test</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.5.2/jasmine.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.5.2/jasmine-html.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.5.2/boot.js"></script>
    
    <script src="https://code.jquery.com/jquery-2.0.3.min.js"></script>
    <script src="https://code.angularjs.org/1.5.8/angular.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.8/angular-mocks.js"></script>

    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.5.2/jasmine.min.css" />

    <!-- The application code -->
    <script src="app.js"></script>
    <!-- The test specs -->
    <script src="app.spec.js"></script>
  </head>
  <body>
    <div id="HTMLReporter" class="jasmine_reporter"></div>
  </body>
</html>

// suggested by: http://stackoverflow.com/a/40155728/4784342
describe('simple directive', function() {
  var $http, $timeout, scope, MyFactory, $httpBackend;

  var ROUTES = {
      get: 'mocked-get-path'
  };

  beforeEach(module('MyApp', function ($provide) {
      $provide.constant('ROUTES', ROUTES);
  }));

  beforeEach(module('MyApp'));

  beforeEach(inject(function(_$rootScope_, _$http_, _$timeout_, _MyFactory_, _$httpBackend_) {
    $httpBackend = _$httpBackend_;
    scope = _$rootScope_.$new();
    $http = _$http_;
    $timeout = _$timeout_;
    MyFactory = _MyFactory_;
  }));

  it('should use ROUTES.get on method myGet', function(done) {
    spyOn(Math, "random").and.returnValue(0.01);
    spyOn($http, "get").and.callThrough();
    
    MyFactory.myGet('elem1')
      .then(function(res) {
        expect($http.get).toHaveBeenCalledWith(ROUTES.get, {params: {id: 'elem1'}});
        done();
      });
    
$httpBackend
    .when('GET', "mocked-get-path?id=elem1")
    .respond(200, { foo: 'bar' });
      
   $timeout.flush(100);
   $timeout.verifyNoPendingTasks();
           $httpBackend.flush();

  });
});