public void TestIsSoldOut()
{
//arrange
Catering catering = new Catering(fa);
CateringItem[] items = catering.GetInventory();
string code = items[0].ProductCode; //first item
catering.AddMoney("2000");
//act
catering.MakePurchase(code, "50");
//assert
Assert.IsTrue(catering.IsSoldOut(code));
}