带Karma的AngularJS测试控制器

angular.module('mean').controller('ItemsController',['$scope',function ($scope) {
  $scope.contentTemplate = '/views/items/index.html';
  $scope.subMenu = [
    {name: 'Create Item',location: '/items/create'}
  ];
}]);

我的测试非常简单：

describe('ItemsController',function () {
    var scope;

    beforeEach(module('mean'));

    beforeEach(inject(function($controller,$rootScope) {
      scope = $rootScope.new();
      $controller('ItemsController',{
        $scope: scope
      });

    }));


    it('should have sub menu items loaded properly',function () {
      expect(scope.subMenu.length).toBe(1);
    });

  });

我想要的是测试有一个subMenu项目.相反,我得到的错误是：

PhantomJS 1.9.7 (Mac OS X) ItemsController should have sub menu items
loaded properly FAILED TypeError: ‘undefined’ is not a function
(evaluating ‘$rootScope.new()’)

是不是注入了$rootScope？那为什么它未定义？