public ViewResult Checkout(Cart cart, ShippingDetails shippingDetails)
        {
            if (!cart.Lines.Any())
                ModelState.AddModelError("", "Извините, ваша корзина пуста!");

            if (ModelState.IsValid)
            {
                _orderProcessor.ProcessOrder(cart, shippingDetails);
                cart.Clear();

                return View("Completed");
            }

            return View(shippingDetails);
        }
        public void Can_Clear_Cart()
        {
            var game1 = new Game {GameId = 1, Name = "Игра1", Price = 100};
            var game2 = new Game {GameId = 2, Name = "Игра2", Price = 55};

            var cart = new Cart();

            cart.AddItem(game1, 1);
            cart.AddItem(game2, 1);
            cart.AddItem(game1, 5);
            cart.Clear();

            Assert.AreEqual(cart.Lines.Count(), 0);
        }