public void DegradeNormalItem() { var item = new Item { Name = "normal", SellIn = 1, Quality = 5 }; var app = new GildedRose(null); // check decreases by 1 app.DegradeNormalItem(item); Assert.AreEqual(4, item.Quality); Assert.AreEqual(0, item.SellIn); // check decreases by 2 when past sell by app.DegradeNormalItem(item); Assert.AreEqual(2, item.Quality); Assert.AreEqual(-1, item.SellIn); }