Our client is an online marketplace, here is a sample of some of the products available on our site:

Product Code	Name	Price
001	Lavender heart	£9.25
002	Personalised cufflinks	£45.00
003	Kids T-shirt	£19.95

This is just an example of products, your system should be ready to accept any kind of product. Our marketing team want to offer promotions as an incentive for our customers to purchase these items. If you spend over £60, then you get 10% off of your purchase. If you buy 2 or more lavender hearts then the price drops to £8.50. Our check-out can scan items in any order, and because our promotions will change, it needs to be flexible regarding our promotional rules. The interface to our checkout looks like this (shown in Ruby):

co = Checkout.new(promotional_rules)
co.scan(item)
co.scan(item)
price = co.total

Implement a checkout system that fulfills these requirements. Do this outside of any frameworks. We’re looking for candidates to demonstrate their knowledge of TDD.

Test data
---------
Basket: 001,002,003
Total price expected: £66.78

Basket: 001,003,001
Total price expected: £36.95

Basket: 001,002,001,003
Total price expected: £73.76