public async Task GetTrolleyTotal() { // Arrange var trolleyRequest = new TrolleyRequest { Products = new List <ProductRequest> { new ProductRequest { Name = "Test A", Price = 14 } }, Specials = new List <SpecialRequest> { new SpecialRequest { Quantities = new List <QuantityRequest> { new QuantityRequest { Name = "Test B", Quantity = 1 } } } }, Quantities = new List <QuantityRequest> { new QuantityRequest { Name = "Test C" , Quantity = 1 } } }; _trolleyService.GetTrolleyTotalAsync(trolleyRequest).Returns(Task.FromResult(14m)); // Act var actionResult = await _controller.GetTrolleyTotal(trolleyRequest); var result = actionResult.Result as OkObjectResult; var total = (decimal)result.Value; // Assert Assert.IsAssignableFrom <decimal>(total); Assert.Equal(14, total); }