Serenity Dojo Katas

This repository contains training materials used as part of the Serenity Dojo mentoring programme.

The Supermarket Checkout Kata in TypeScript

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 checkout that can scan articles from a shopping cart and produce a receipt.

The supermarket has a catalogue 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, for example:

• 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 change each week, so need to be easily configurable.

Goal

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

• The checkout 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 special deals:
  • 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 system can be configured with multiple different special deals, so the teller should be able to correctly detect and apply all the special deals applicable to a given shopping cart. To keep things simple you can assume that there will be up to one deal per product category.

There is a simple failing test in spec/checking_out.spec.ts to get you started.

Running the tests

The tests that you'll find under spec directory are written using Mocha test framework and Chai assertion library. They are configured to use Chai's expect assertion style and can be executed as follows:

• to run the tests once and generate the test coverage report (coverage/index.html), run the following command:

npm test

• to re-run the tests automatically as soon as you save your changes, run:

npm run test:watch