ruby-tests-directory-structure

Create a new directory
> mkdir foo
> cd foo

Install bundler
> gem install bundler

Create a gem file and add the following gem
> vi Gemfile

source 'https://rubygems.org'
gem 'minitest', '~> 5.3.4'

> bundle install

Create the following directory structure
> mkdir lib test

Create a class
> vi lib/meme.rb

class Meme
  def i_can_has_cheezburger?
    "OHAI!"
  end

  def will_it_blend?
    "YES!"
  end
end

Create a minitest
> vi test/test_meme.rb

require "minitest/autorun"
require_relative '../lib/meme'

class TestMeme < Minitest::Test
  def setup
    @meme = Meme.new
  end

  def test_that_kitty_can_eat
    assert_equal "OHAI!", @meme.i_can_has_cheezburger?
  end

  def test_that_it_will_not_blend
    refute_match /^no/i, @meme.will_it_blend?
  end

  def test_that_will_be_skipped
    skip "test this later"
  end
end

or BDD style

require 'minitest/autorun'
require_relative '../lib/meme'

describe Meme do
  before do
    @meme = Meme.new
  end

  describe 'when asked about cheeseburgers' do
    it 'must respond positively' do
      @meme.i_can_has_cheezburger?.must_equal 'OHAI!'
    end
  end

end

Run the test
> ruby test/test_meme.rb

3 runs, 3 assertions, 0 failures, 0 errors, 1 skips

Voila!

Links that help
http://ruby.learncodethehardway.org/book/ex46.html
http://www.airpair.com/testing/learn-ruby-test-driven-development
https://github.com/seattlerb/minitest
http://bundler.io/