public void SingleMultibuy() { var basket = new List <BasketItem>() { new BasketItem("A", 3, 50M) }; var promotions = new List <Promotion>() { new Promotion("3A for 130", Promotions.MakeMultibuy("A", 3, 130M)) }; var result = Promotions.TotalAfterPromotions(basket, promotions); result.Should().Be(130); }