public async void AddModelAsync_Returns_Model_Guid() { Guid guid = Guid.NewGuid(); var modelr = new Mock <IVehicleModel>(); modelr.Setup(s => s.Id).Returns(guid); repoMock.Setup(s => s.AddAsync(It.IsAny <IVehicleModel>())).Returns(Task.FromResult(modelr.Object)); uowMock.SetupGet(s => s.Models).Returns(repoMock.Object); var modelService = new VehicleModelService(uowMock.Object); var model = await modelService.AddModelAsync(modelr.Object); //Assert Assert.NotNull(model); Assert.Equal(guid, model.Id); }