Berlin Uhr - http://content.codersdojo.org/code-kata-catalogue/berlin-clock/

00:00:00.txt

Y
OOOO
OOOO
OOOOOOOOOOO
OOOO

13:17:01.txt

O
RROO
RRRO
YYROOOOOOOO
YYOO

23:59:59.txt

O
RRRR
RRRO
YYRYYRYYRYY
YYYY

24:00:00.txt

Y
RRRR
RRRR
OOOOOOOOOOO
OOOO

berlin_uhr.rb

class BerlinUhr

  attr_reader :h, :m, :s

  def initialize(timestamp)
    @timestamp = timestamp
    @h, @m, @s= timestamp.split(':').map(&:to_i)
  end

  def to_s
    [seconds, hours, minutes].flatten.join("\n")
  end

  private
  def hours
    m, r = h.divmod(5)

    [
      ('R' * m).ljust(4, 'O'),
      ('R' * r).ljust(4, 'O')
    ]
  end

  def minutes
    d, r = m.divmod(5)

    [
      'YYRYYRYYRYY'.slice(0,d).ljust(11, 'O'),
      ('Y' * r).ljust(4, 'O')
    ]
  end

  def seconds
    s.even? ? 'Y' : 'O'
  end
end

berlin_uhr_spec.rb

require './berlin_uhr'

describe BerlinUhr do

  fixtures = Dir[File.expand_path('../*', __FILE__)].map do |file|
    [File.basename(file, '.txt'), File.read(file)]
  end

  fixtures.each do |time, output|
    it "returns the proper output for #{time.inspect}" do
      expect(described_class.new(time).to_s).to eq output.strip
    end
  end


end