public void SinglePairedBuy()
{
var basket = new List <BasketItem>()
{
new BasketItem("C", 1, 20M),
new BasketItem("D", 1, 15M)
};
var promotions = new List <Promotion>()
{
new Promotion("C + D for 30", Promotions.MakePairedBuy("C", "D", 30M))
};
var result = Promotions.TotalAfterPromotions(basket, promotions);
result.Should().Be(30);
}
