A relatively involved code test I completed in 2013 for an e-commerce company.

bundle 
rake spec
rake cucumber

Here is a sample of some of the products available on our site:

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 your purchase If you buy 2 or more travel card holders 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.

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