Kata Roman Numbers TDD

TDD experienced with the kata Roman Numbers

This project aims to record my steps when working on the kata Roman Numbers following the Test Driven Development methodology.

Problem description

“As a Roman Bookkeeper I want to add Roman numbers because doing it manually is too tedious.”

Given the Roman numerals, (IVXLCDM which means one, five, ten, fifty, hundred, fivehundred and a thousand respectively), create two numbers and add them. As we are in Rome there is no such thing as decimals or int, we need to do this with the strings. An example would be “XIV” + “LX” = “LXXIV”

There are some rules to a Roman number:

Numerals can be concatenated to form a larger numeral (“XX” + “II” = “XXII”)
If a lesser numeral is put before a bigger it means subtraction of the lesser from the bigger (“IV” means four, “CM” means ninehundred)
If the numeral is I, X or C you can’t have more than three (“II” + “II” = “IV”)
If the numeral is V, L or D you can’t have more than one (“D” + “D” = “M”)

TDD

The 3 rules

No production code, unless if it fix a failing test
No more test code than the minimum to make it fail (don't forget that: not compiling is failing)
No more production code than the minimum to fix the failing test

### Mantra : Fail Fix Refactor

Write failing test
Fix test by writing code
Refactor if needed

Baby steps

One change at a time

Install

git clone

npm install

Run tests

run tests once

npm run test

run tests watching for modifications

npm run test-watch