public void should_calculate_discounted_price_of_a_single_item_when_offer_can_be_applied()
{
var data = new List <Product>
{
new Product('A', 50m, new PercentageOffer(0.9m))
};
var pricingRepository = new InMemoryRepository(data);
var checkout = new Checkout(pricingRepository);
var discountedPrice = checkout.CalculatePriceFor("A");
Assert.Equal(45m, discountedPrice);
}