rps.rb

require 'minitest/autorun'

def rock(other)
  case other
  when :rock then 0
  when :paper then :paper
  when :scissors then :rock
  else
    raise "unknown value: #{other}"
  end
end

def paper(other)
  case other
  when :rock then :paper
  when :paper then 0
  when :scissors then :scissors
  else
    raise "unknown value: #{other}"
  end
end

def scissors(other)
  case other
  when :rock then :rock
  when :paper then :scissors
  when :scissors then 0
  else
    raise "unknown value: #{other}"
  end
end

def winner(left, right)
  send(left, right)
end

describe "winner" do
  it "must" do
    winner(:rock, :rock).must_equal 0
    winner(:rock, :paper).must_equal :paper
    winner(:rock, :scissors).must_equal :rock
    winner(:paper, :rock).must_equal :paper
    winner(:paper, :paper).must_equal 0
    winner(:paper, :scissors).must_equal :scissors
    winner(:scissors, :rock).must_equal :rock
    winner(:scissors, :paper).must_equal :scissors
    winner(:scissors, :scissors).must_equal 0
  end
end