Basic setup for a Ruby-based TDD Code Kata

In the last weeks with the guys of the Firenze Ruby Social Club we started to think about organizing some Code Katas to play with test-driven development and yesterday we met to play with The Game of Life.

We used Ruby and RSpec with a simple setup that I want to report here if you’d like to play with some katas.

Although probably a Kata exercise won’t need many gems, in ruby projects I like to always use a Gemfile with the required gems:

ruby '2.1.2'
source ''
gem 'rspec'

After a bundle install you’re ready to start writing some code (if you don’t have the bundle command, install the bundler gem with gem install bundler).

A basic example to begin TDD with the Game of Life could be this:


require './game_of_life'

describe GameOfLife::Universe do
  it "should have an initial size" do
    u =
    expect(u.size).to eq(36)


module GameOfLife
  class Universe
    attr_reader :size
    def initialize(side)
      @size = side**2

With this minimalistic setup, the test passes:

~$ bundle exec rspec --color game_of_life_spec.rb

Finished in 0.00095 seconds (files took 0.0966 seconds to load)
1 example, 0 failures

You’re now ready to start playing with TDD in Ruby :)