TypeError:无法读取属性'那么'在使用Karma测试AngularJS控制器时未定义的

我正试图为一个得到服务承诺的控制器编写单元测试，但在Jasmine中我得到了：

TypeError: Cannot read property 'then' of undefined

在控制器中，我根据服务返回的承诺调用.then()。

有人能帮忙吗？我肯定错过了一些显而易见的东西。

这是一个砰的一声：http://plnkr.co/edit/vJOopys7pWTrTQ2vLgXS?p=preview

'use strict';
describe('Language controller', function() {
    var scope, translationService, createController;
    beforeEach(function() {
        var mockTranslationService = {};
        module('dictApp', function($provide) {
            $provide.value('translationService', mockTranslationService);
        });
        inject(function($q) {
            mockTranslationService.languages = [
                {
                    name: 'slovak'
                },
                {
                    name: 'czech'
                }
            ];
            mockTranslationService.languagesWithWords = [{
                name: 'slovak',
                words: [{
                    key: 'Car',
                    translation: 'Auto',
                    createdOn: 0
                }, {
                    key: 'Flower',
                    translation: 'Kvet',
                    createdOn: 0
                }]
            }, {
                name: 'czech',
                words: {
                    key: 'Plaza',
                    translation: 'Namesti',
                    createdOn: 0
                }
            }];
            mockTranslationService.getLanguages = function() {
                var deferred = $q.defer();
                deferred.resolve(this.languages);
                return deferred.promise;
            };
        });
    });
    beforeEach(inject(function($controller, $rootScope, _translationService_) {
        scope = $rootScope.$new();
        translationService = _translationService_;
        createController = function () {
            return $controller('LanguageCtrl',
                    {$scope: scope, translationService: translationService});
        };
        scope.$digest();
    }));
    it('should get the language array', function() {
        spyOn(translationService, 'getLanguages');
        createController();
        expect(translationService.getLanguages).toHaveBeenCalled();
    });
});

这就是控制器：

   dictControllers.controller('LanguageCtrl', ['$scope', 'translationService', function($scope, translationService){

        $scope.getLanguages = function() {
            translationService.getLanguages().then(function(){
                $scope.languages = translationService.languages;
            });
        };
        $scope.getLanguages();
        $scope.getWords = function(language) {
            translationService.getWords(language);
        };

        $scope.newWord = {};
        $scope.addWord = function(language) {
            translationService.addWord($scope.newWord, language);
            $scope.newWord = {};
            };
    }]);