public ActionResult CheckOut(Carrito carrito)
        {
            if (carrito.GetItems().Count == 0)
            {
                ModelState.AddModelError(string.Empty, "No tiene compras efectuadas!!!");
            }

            var carritoVm = _mapper.Map <CarritoListViewModel>(carrito);

            return(View(carritoVm));
        }
        // GET: Carrito
        public ActionResult Index(Carrito carrito, string returnUrl)
        {
            List <ItemCarritoListViewModel> listaItems = _mapper.Map <List <ItemCarritoListViewModel> >(carrito.GetItems());

            return(View(new CarritoListViewModel
            {
                Items = listaItems,
                ReturnUrl = returnUrl
            }));
        }