Angularjs unit testing service with promise

I'm trying to unit test a service that uses a repository which in turn returns a promise to the consumer.
I'm having trouble testing the promise, or I should say I don't know how test the promise.
Any help would be appreciated!

Test.js

var describe = window.describe,
    beforeEach = window.beforeEach,
    afterEach = window.afterEach,
    it = window.it,
    expect = window.expect,
    inject = window.inject,
    module = window.module,
    angular = window.angular,
    sessionLimitServiceResponse;

describe('Jasmine - SessionLimitService', function () {

    beforeEach(module('sessionlimit.module'));

    var sessionLimitServiceMock, q;

    beforeEach(inject(function (_SessionLimitService_, _SessionLimitResository_, $q) {
        sessionLimitServiceMock = _SessionLimitService_;

        spyOn(_SessionLimitResository_, "getData").and.returnValue(function () {
            var deferred = $q.defer();
            deferred.resolve("Remote call result");
            return deferred.promise;
        });

        q = $q;

    }));

    beforeEach(function () {
        sessionLimitServiceMock = {
            content: [],

            getData: function() {
                // mock promise
                var deferred = q.defer();
                deferred.resolve('foo');
                return deferred.promise;
            }
        };

        spyOn(sessionLimitServiceMock, 'getData').and.callThrough();
    });

    it("Content array must be empty", function () {
        expect(sessionLimitServiceMock.content.length).toEqual(0);
    });

    it('Ensure that the method was invoked', function () {
        sessionLimitServiceMock.getData(); // UNSURE OF THIS AS WELL
        expect(sessionLimitServiceMock.getData).toHaveBeenCalled();
    });

    it('Content array must have a value', function() {
        sessionLimitServiceMock.getData().then(function(value) {
            expect(value).toEqual('foo'); // NOTHING HAPPENS
        });
    });
});

Service.js

(function (ng, app) {

    var sessionLimitRepository = function ($http) {
        var repository = {};

        repository.getData = function () {
            var url = '/' + Techsson.Core.Global.Language + '/api/sessionlimit/getdata';
            var result = $http.get(url);
            return result;
        }

        return repository;
    };

    app.factory('SessionLimitResository', ['$http', sessionLimitRepository]);
}(window.angular, angular.module('sessionlimit.module')));

(function (ng, app) {
    var sessionLimitService = function(sessionLimitRepository, $q) {
        var service = {};
        service.content = [];

        service.getData = function () {
            var deferred = $q.defer();

            if (service.content.length > 0) {
                deferred.resolve();
                return deferred.promise;
            };

            var promise = sessionLimitRepository.getData();
            promise.success(function(payload) {
                service.content.push(payload);
                deferred.resolve();
            }).error(function() {
                deferred.reject();
            });

            return deferred.promise;
        };

        return service;
    };

    app.factory('SessionLimitService', ['SessionLimitResository', '$q', sessionLimitService]);
}(window.angular, angular.module('sessionlimit.module')));