private void AddButton_Click(object sender, RoutedEventArgs e)
        {
            int price = 0;

            try
            {
                price = Int32.Parse(Price.Text);
            }
            catch (Exception ex)
            {
                price = 0;
            }
            int count = 0;

            try
            {
                count = Int32.Parse(Count.Text);
            }
            catch (Exception ex)
            {
                count = 0;
            }

            Supply supply = new Supply()
            {
                Product = new TradePointProduct()
                {
                    Product    = ProductComboBox.SelectedItem as Product,
                    Supplier   = SupplierComboBox.SelectedItem as Supplier,
                    TradePoint = TradePointComboBox.SelectedItem as TradePoint,
                    Price      = price,
                    Count      = count
                },
                Order = OrderComboBox.SelectedItem as Order,
                Date  = DateTime.Today
            };

            SuppliesController.GetInstance().AddSupply(supply);
        }
        public async Task Post_BadParamsInvalid_BadRequest()
        {
            //Arrange
            ISupplyService supplyServiceStub =
                Substitute.For <ISupplyService>();

            SupplyCreateModel supplyCreateModel = new SupplyCreateModel()
            {
                Provider    = null,
                ProvideDate = DateTimeOffset.Now
            };

            SuppliesController suppliesController = new SuppliesController(supplyServiceStub);

            suppliesController.ModelState.AddModelError("Name", "Required");


            //Act
            IActionResult badRequestObjectResult = await suppliesController.Post(supplyCreateModel);


            //Assert
            Assert.IsType <BadRequestObjectResult>(badRequestObjectResult);
        }