public void GivenAnOrderDiscount_WhenApplyToNonOrder_ThenShouldReturnZero()
        {
            var sut = new OrderDiscount("d", 1);
            var line = new Line(new Bike(string.Empty, string.Empty, 1), 1);

            Assert.AreEqual(0, sut.Apply(line));
        }
        public void GivenAnOrderDiscount_WhenApplyToOrder_ThenShouldReturnOrderSubTotalTimesPercentage()
        {
            var sut = new OrderDiscount("d", 1);
            var order = new Order(string.Empty);

            order.AddLine(new Line(new Bike(string.Empty, string.Empty, 1), 1));

            Assert.AreEqual(order.CalculateSubTotal() * sut.Percentage, sut.Apply(order));
        }