public void ReadAllDronesIncludeManufacturersEnsureRepositoryIsCalled() { var droneRepo = new Mock <IDroneRepository>(); IDroneService service = new DroneService(droneRepo.Object); var isCalled = false; droneRepo.Setup(x => x.GetAllDronesIncludeManufacturers()).Callback(() => isCalled = true).Returns(new FilteredList <Drone>()); service.GetAllDronesIncludeManufacturers(); Assert.True(isCalled); }