Tengo un ParseService, del que me gustaría burlarme para probar todos los controladores que lo usan, he estado leyendo sobre espías de jazmín, pero aún no está claro. ¿Alguien podría darme un ejemplo de cómo simular un servicio personalizado y usarlo en la prueba del controlador?

Ahora mismo tengo un controlador que usa un servicio para insertar un libro:

BookCrossingApp.controller('AddBookCtrl', function ($scope, DataService, $location) {

    $scope.registerNewBook = function (book) {
        DataService.registerBook(book, function (isResult, result) {

            $scope.$apply(function () {
                $scope.registerResult = isResult ? "Success" : result;
            });
            if (isResult) {
                //$scope.registerResult = "Success";
                $location.path('/main');
            }
            else {
                $scope.registerResult = "Fail!";
                //$location.path('/');
            }

        });
    };
});

El servicio es así:

angular.module('DataServices', [])

    /**
     * Parse Service
     * Use Parse.com as a back-end for the application.
     */
    .factory('ParseService', function () {
        var ParseService = {
            name: "Parse",

            registerBook: function registerBook(bookk, callback) {

                var book = new Book();

                book.set("title", bookk.title);
                book.set("description", bookk.Description);
                book.set("registrationId", bookk.RegistrationId);
                var newAcl = new Parse.ACL(Parse.User.current());
                newAcl.setPublicReadAccess(true);
                book.setACL(newAcl);

                book.save(null, {
                    success: function (book) {
                        // The object was saved successfully.
                        callback(true, null);
                    },
                    error: function (book, error) {
                        // The save failed.
                        // error is a Parse.Error with an error code and description.
                        callback(false, error);
                    }
                });
            }
        };

        return ParseService;
    });

Y mi prueba hasta ahora se parece a esto:

describe('Controller: AddBookCtrl', function() {

    //  // load the controller's module
    beforeEach(module('BookCrossingApp'));


    var AddBookCtrl, scope, book;

    // Initialize the controller and a mock scope
    beforeEach(inject(function($controller, $rootScope) {
        scope = $rootScope;
        book = {title: "fooTitle13"};
        AddBookCtrl = $controller('AddBookCtrl', {
            $scope: scope
        });
    }));

    it('should call Parse Service method', function () {

        //We need to get the injector from angular
        var $injector = angular.injector([ 'DataServices' ]);
        //We get the service from the injector that we have called
        var mockService = $injector.get( 'ParseService' );
        mockService.registerBook = jasmine.createSpy("registerBook");
        scope.registerNewBook(book);
        //With this call we SPY the method registerBook of our mockservice
        //we have to make sure that the register book have been called after the call of our Controller
        expect(mockService.registerBook).toHaveBeenCalled();
    });
    it('Dummy test', function () {
        expect(true).toBe(true);
    });
});

En este momento la prueba está fallando:

   Expected spy registerBook to have been called.
   Error: Expected spy registerBook to have been called.

¿Que estoy haciendo mal?