public void DecreaseUnits_ExecutesUnderlyingMethodInTheBasket() { //Arrange var basketService = new Mock <IProductBasketService>(); basketService.Setup(m => m.DecreaseUnits(It.IsAny <string>())); //Act var controller1 = new BasketController(basketService.Object); controller1.DecreaseUnits("s"); //Assert basketService.Verify(m => m.DecreaseUnits(It.IsAny <string>()), Times.Once); }