public void TestComboOfferCalculation_extraItems()
{
Product productA = new Product();
productA.productName = "A";
productA.productPrice = 50;
productA.productType = "clothing";
productA.discountList = new List <string>();
ComboOffer productA_Combo = new ComboOffer(productA, 3, 130);
float Price = productA_Combo.calculatePrice(5);
Assert.AreEqual(230, Price);
}