This is a variation of a popular kata described in http://codekata.com/kata/kata01-supermarket-pricing/. The aim of the exercise is to build an automated teller that can check out articles from a shopping cart.

The supermarket has a catalog with different types of products (rice, apples, milk, toothbrushes,...). Each product has a price, and the total price of the shopping cart is the total of all the prices.

But the supermarket also runs special deals, e.g.

• Buy two toothbrushes, get one free
• 10% discount on rice
• 20% discount on apples if you buy more than 10
• Bags of 1 kg of oranges $4 instead of $5.

These are just examples: the actual special deals changes each week, so needs to be easily configurable.

The goal of the exercise is to implement a teller that can handle the following scenarios (and more - use your imagination!)

• The teller should be able to handle a shopping cart with no special deals

• The client should get a receipt with the list of purchases and the total price.

• The teller should be able to handle the following scenarios

  • Buy 2 get one free
  • Buy 4 get one free
  • 10% discount on a certain product (e.g. 10% discount on 1kg packets of rice)
  • 20% discount on a certain product if you buy more than 10 (e.g 20% discount on apples for 11 or more apples)
  • Fixed discounts (e.g. bag of 1kg of oranges costs $4 instead of $5).

• The teller should be able to handle combinations of the above scenarios, when there is more than one special deal in the shopping cart items.

There is a simple failing test in WhenCheckingOutArticlesAtTheSupermarket to get you started.