public void Add_ReturnsBadRequest()
        {
            // Arrange
            var nameMissingItem = new InventoryItem()
            {
                Manufacturer = "Man",
                Price        = 100
            };

            _controller.ModelState.AddModelError("Name", "Required");
            // Act
            var badResponse = _controller.Post(nameMissingItem).Result;

            // Assert
            Assert.IsType <BadRequestResult>(badResponse);
        }