我是Angular JS的新手，正尝试以适当的TDD方式从中提取出一些东西，但是在测试时却遇到此错误：

喷油器已创建，无法注册模块！

这就是我正在谈论的服务。

bookCatalogApp.service('authorService', ["$resource", "$q", function($resource, $q){

    var Author =$resource('/book-catalog/author/all',{},{
        getAll : { method: 'GET', isArray: true}
    });

    var authorService = {};

    authorService.assignAuthors = function(data){
        authorService.allAuthors = data;
    };

    authorService.getAll = function(){
        if (authorService.allAuthors)
            return {then: function(callback){callback(authorService.allAuthors)}}

        var deferred = $q.defer();
        Author.getAll(function(data){
            deferred.resolve(data);
            authorService.assignAuthors(data);
        });
        return deferred.promise;
    };

    return authorService;
}]);

这是对以上服务的测试

describe("Author Book Service",function(){
    var authorService;
    beforeEach(module("bookCatalogApp"));
    beforeEach(inject(function($injector) {
        authorService = $injector.get('authorService');
    }));

    afterEach(function() {
        httpBackend.verifyNoOutstandingExpectation();
        httpBackend.verifyNoOutstandingRequest();
    });

    describe("#getAll", function() {
        it('should get all the authors for the first time', function() {
            var authors = [{id:1 , name:'Prayas'}, {id:2 , name:'Prateek'}];

            httpBackend.when('GET', '/book-catalog/author/all').respond(200, authors);

            var promise = authorService.getAll();

            httpBackend.flush();
            promise.then(function(data){
                expect(data.length).toBe(2)
            });
        });

        it('should get all the authors as they have already cached', function() {
            authorService.allAuthors = [{id:1 , name:'Prayas'}, {id:2 , name:'Prateek'}];

            var promise = authorService.getAll();

            promise.then(function(data){
                expect(data.length).toBe(2)
            });
        });

    });
})

任何帮助将不胜感激。