Here is my solution for the greed problem from the edgecase Koans https://github.com/edgecase/ruby_koans

greed_scorer.rb

class GreedScorer
  def initialize(dice)
    @dice = dice
  end
  
  def score
    the_1000_point_score + other_triple_score + score_for_ones + score_for_fives
  end
  
  private
  def the_1000_point_score
    the_triple == 1 ? 1000 : 0
  end
  
  def other_triple_score
    the_triple > 1 ? the_triple * 100 : 0
  end
  
  def score_for_ones
    @dice.count(1)%3 * 100
  end
  
  def score_for_fives
    @dice.count(5)%3 * 50
  end
  
  def the_triple
    value, = @dice.group_by{|i| i}.find {|value, rolls| rolls.size >= 3}
    value || 0
  end
end

greed_scorer_test.rb

class GreedScorerTest < Test::Unit::TestCase
  
  def test_three_ones_1000_points
    assert_equal 1000, GreedScorer.new([2,1,2,1,1]).score
  end
  
  def test_three_of_any_number_yields_100_times_that_number_points
    assert_equal 200, GreedScorer.new([2,2,2,4,4]).score
    assert_equal 300, GreedScorer.new([3,3,3,4,4]).score
    assert_equal 400, GreedScorer.new([4,4,4,2,2]).score
    assert_equal 500, GreedScorer.new([5,5,5,4,4]).score
    assert_equal 600, GreedScorer.new([6,6,6,4,4]).score
  end
  
  def test_a_one_is_worth_one_hundred_points
    assert_equal 100, GreedScorer.new([2,1,2,4,4]).score
    assert_equal 200, GreedScorer.new([2,1,1,4,4]).score
    assert_equal 1100, GreedScorer.new([2,1,1,1,1]).score
    assert_equal 1200, GreedScorer.new([1,1,1,1,1]).score
  end
  
  def test_a_five_is_worth_fifty_points
    assert_equal 50, GreedScorer.new([2,5,2,4,4]).score
    assert_equal 100, GreedScorer.new([2,5,5,4,4]).score
    assert_equal 550, GreedScorer.new([2,5,5,5,5]).score
    assert_equal 600, GreedScorer.new([5,5,5,5,5]).score
  end
  
  def test_mix_of_scoring_outcomes
    assert_equal 700, GreedScorer.new([1,1,5,5,5]).score
    assert_equal 250, GreedScorer.new([5,1,6,6,1]).score
    assert_equal 1150, GreedScorer.new([5,1,1,1,1]).score
  end
end