public void Discount_WhenZeroAmount_ThenPriceStaysTheSame()
{
var price = 4.5M.ToPrice();
var discount = new TwoPlusOneFreeDiscountPolicy(amount: 0);
var priceAfterDiscount = discount.CalculatePrice(price);
Assert.That(priceAfterDiscount, Is.EqualTo(price));
}
public void Discount_WhenAmountGraterOrEqualThree_ThenApplyDiscount(int amount, decimal priceValue, decimal expectedDiscount)
{
var price = new Price(priceValue);
var discount = new TwoPlusOneFreeDiscountPolicy(amount);
var priceAfterDiscount = discount.CalculatePrice(price);
Assert.That(priceAfterDiscount, Is.EqualTo(expectedDiscount.ToPrice()));
}