weather_bot.rb

class WeatherBot
  def name; self.class.name; end
  def play(last=nil)
    if !last or last == '' then 'r'
    else @always_play ||= beats(last) end
  end
  def beats(play)
    if paper?(play) then 's'
    elsif rock?(play) then 'p'
    else 'r' end
  end
  %w(paper rock scissors).each do |e|
    define_method("#{e}?"){|i| (e[0,1] == i[0,1].downcase)}
  end
end

if __FILE__ == $0
  require 'test/unit'
  class WeatherBotTest < Test::Unit::TestCase
    def test_beats
      assert_equal 'r', w.beats('s')
      assert_equal 'p', w.beats('r')
      assert_equal 's', w.beats('p')
    end
    def test_play
      assert_equal 'r', w.play
      assert_equal 'r', w.play('')
      assert_equal 's', w.play('p')
      assert_equal 's', w.play('r')
      assert_equal 's', w.play('r')
      assert_equal 's', w.play('s')
    end
    def test_check_methods
      assert w.paper?('Paper')
      assert !w.paper?('r')
      assert w.rock?('r')
      assert !w.rock?('Scissors')
      assert w.scissors?('scisors')
      assert !w.scissors?('P')
    end
    def w; @w ||= WeatherBot.new; end
  end
end