public void GetItemTotalPriceTest()
{
_itemOrder.AddToOrder("item0");
_itemOrder.UpdateQuantity(0, 5);
Assert.AreEqual(_itemInfo.GetItemPrice("item0") * 5, _itemOrder.GetItemTotalPrice(0));
Assert.AreEqual(0, _itemOrder.GetItemTotalPrice(-1));
Assert.AreEqual(0, _itemOrder.GetItemTotalPrice(1));
}