public void SetOutputDeviceTest() { //Arrange _persistanceManager.Setup(x => x.Save(It.IsAny <string>(), It.IsAny <string>())).Verifiable(); //Act _soundService.SetOutputDevice(Guid.Empty); //Assert _persistanceManager.Verify(x => x.Save(It.IsAny <string>(), It.IsAny <string>()), Times.Once); }