README.txt

Rock Paper Scissors Lizard Spock is a more convoluted and much geekier version of Rock Paper Scissors.

The rules are:

Rock beats Scissors
Rock crushes Lizard
Paper covers Rock
Paper disproves Spock
Scissors cut Paper
Scissors decapitate Lizard
Lizard poisons Spock
Lizard eats Paper
Spock melts Scissors
Spock vaporizes Rock

Like for Like is a draw

Create the game, which accepts one of the five items as an argument and has the computer pick an item at random, then gives feedback on who won and who lost.

rpsls.rb

class Game
  GESTURE_COMPARISONS = { :paper => [:rock, :spock],
                          :rock => [:scissors, :lizard],
                          :scissors => [:paper, :lizard],
                          :lizard => [:spock, :paper],
                          :spock => [:rock, :scissors] }

  attr_accessor :opponent_gesture

  def initialize

  end

  def play(gesture)
    raise Exception unless valid_gestures.include?(gesture)
    @gesture = gesture
    calculate_winner
  end

  private
    def opponent_gesture
      @opponent_gesture ||= valid_gestures.choice
    end

    def valid_gestures
      GESTURE_COMPARISONS.keys.map { |k| k.to_s.capitalize }
    end

    def calculate_winner
      return "Draw" if @gesture == opponent_gesture

      if user_wins
        "Winner: #{@gesture} beats #{opponent_gesture}"
      else
        "Loser: #{opponent_gesture} beats #{@gesture}"
      end
    end

    def user_wins
      GESTURE_COMPARISONS[@gesture.downcase.to_sym].include? opponent_gesture.downcase.to_sym
    end
end

rpsls_spec.rb

require 'rspec'
require 'rpsls.rb'

describe Game do

  let(:rpsls) { described_class.new }


  it 'only accepts a valid gesture' do
    expect{ rpsls.play('Blah') }.to raise_error
  end

  it 'returns "Loser" if the opponent wins' do
    rpsls.opponent_gesture = "Scissors"
    result = rpsls.play('Paper')
    result.should eq('Loser: Scissors beats Paper')
  end

   it 'returns "Winner"' do
    rpsls.opponent_gesture = "Spock"
    result = rpsls.play('Paper')
    result.should eq('Winner: Paper beats Spock')
  end

  it 'returns a "Draw" if both gestures are the same' do
    rpsls.opponent_gesture = "Spock"
    rpsls.play('Spock').should eq('Draw')
  end
end