AdventureWorks.UILogic.ViewModels.ShoppingCartPageViewModel.UpdateShoppingCartAsync C# (CSharp) Метод

        public async void UpdateShoppingCartAsync(object notUsed)
        {
            await UpdateShoppingCartInfoAsync();
        }

        public void CheckoutCommand_NotExecutable_IfNoItemsInCart()
        {
            var navigationService = new MockNavigationService();
            var shoppingCartRepository = new MockShoppingCartRepository();
            shoppingCartRepository.GetShoppingCartAsyncDelegate = () => Task.FromResult<ShoppingCart>(null);
            var eventAggregator = new MockEventAggregator();
            eventAggregator.GetEventDelegate = type => new MockShoppingCartUpdatedEvent();
            var target = new ShoppingCartPageViewModel(shoppingCartRepository, navigationService, null, null, null, null, null, null, eventAggregator);
            target.UpdateShoppingCartAsync(null);
            
            Assert.IsFalse(target.CheckoutCommand.CanExecute());

            shoppingCartRepository.GetShoppingCartAsyncDelegate = 
                () => Task.FromResult(new ShoppingCart(new Collection<ShoppingCartItem>()){Currency = "USD", FullPrice = 0, TaxRate = 0, TotalDiscount = 0, TotalPrice = 0});
            target.UpdateShoppingCartAsync(null);
            
            Assert.IsFalse(target.CheckoutCommand.CanExecute());

            shoppingCartRepository.GetShoppingCartAsyncDelegate =
                () => Task.FromResult(new ShoppingCart(new Collection<ShoppingCartItem> { new ShoppingCartItem{Product = new Product(), Currency = "USD", Quantity = 0} }) 
                { Currency = "USD", FullPrice = 0, TaxRate = 0, TotalDiscount = 0, TotalPrice = 0 });
            target.UpdateShoppingCartAsync(null);

            Assert.IsTrue(target.CheckoutCommand.CanExecute());

        }