public void GetAsync_Return_Empty_List() { //Arrange CityDomainModel cityDomainModel = new CityDomainModel { Id = 123, CinemasList = new List <CinemaDomainModel>(), Name = "Zrenjanin" }; int expectedStatusCode = 200; IEnumerable <CityDomainModel> cityDomainModelsIEn = null; Task <IEnumerable <CityDomainModel> > responseTask = Task.FromResult(cityDomainModelsIEn); _cityService = new Mock <ICityService>(); _cityService.Setup(x => x.GetAllAsync()).Returns(responseTask); CitiesController citiesController = new CitiesController(_cityService.Object); //Act var result = citiesController.GetAsync().ConfigureAwait(false).GetAwaiter().GetResult().Result; var objectResult = ((OkObjectResult)result).Value; List <CityDomainModel> cityDomainModelResultList = (List <CityDomainModel>)objectResult; //Assert Assert.IsNotNull(objectResult); Assert.IsInstanceOfType(result, typeof(OkObjectResult)); Assert.AreEqual(expectedStatusCode, ((OkObjectResult)result).StatusCode); }