public void TestRepoShouldBeCalledOnceIfMachineWatchIsNotEmptyOrNull()
        {
            //Given
            var mockRepo = new Mock <IWatchRepository>();
            var service  = new WatchService(mockRepo.Object);

            MachineWatch mw = new MachineWatch {
                Machine = new Core.Entity.DB.Machine {
                    MachineId = "1"
                },
                WatchId = "1"
            };

            //When
            mockRepo.Setup(mr => mr.SubscribeToMachine(It.IsAny <MachineWatch>()));


            service.SubscribeToMachine(mw);

            //Then
            mockRepo.Verify(mr => mr.SubscribeToMachine(It.IsAny <MachineWatch>()), Times.Once);
        }