public void TestChangeOrder() { CurrentOrder <SushiItem> myOrder = new CurrentOrder <SushiItem>(); double price = 12.8; SushiItem item = new SushiItem("name", price); uint quantity = 12; myOrder.OrderSomething(item, quantity); uint newQuantity = quantity + 1; myOrder.ChangeOrder(new OrderEntity <SushiItem>(item, quantity), newQuantity); Assert.AreEqual(myOrder.TotalSum, item.Price * newQuantity); }