public void Carrito_se_limpia_al_llamar_clear()
        {
            //Arrange
            var carrito = new Cart();
            var p = new Product() {ProductID = 1};
            carrito.Add(p,3);
            const int items = 0;

            //Act
            carrito.Clear();

            //Assert
            Assert.AreEqual(carrito.Lines.Count(),items);
        }
        public ActionResult Checkout(Cart cart,ShippingDetails detalles)
        {
            if (!cart.Lines.Any())
                ModelState.AddModelError("", "Tu carrito esta vacío.");

            if (ModelState.IsValid)
            {
                //Process
                _orderProcessor.Process(cart, detalles);
                cart.Clear();
                return View("Completed");
            }
            return View(detalles);
        }