public void GetItemTotalPriceByIdTest()
{
string id = "item0";
_itemOrder.AddToOrder(id);
_itemOrder.UpdateQuantity(0, 5);
Assert.AreEqual(_itemInfo.GetItemPrice(id) * 5, _itemOrder.GetItemTotalPriceById(id));
Assert.AreEqual(0, _itemOrder.GetItemTotalPriceById("notExitId"));
}