public void TestClearPurchases()
        {
            //arrange
            Catering catering = new Catering(fa);

            CateringItem[] items = catering.GetInventory();
            string         code  = items[0].ProductCode; //first item

            catering.AddMoney("20");
            catering.MakePurchase(code, "1");

            //act
            CateringItem[] purchases = catering.GetPurchases();

            //assert
            Assert.AreEqual(1, purchases.Length);

            //act
            catering.ClearPurchases();
            purchases = catering.GetPurchases();

            //assert
            Assert.AreEqual(0, purchases.Length);
        }