tennis_game_kata.rb

# Kata description: http://codingdojo.org/cgi-bin/index.pl?KataTennis

module Tennis
  class Player
    attr_reader :name, :points_won

    def initialize(name)
      @name = name
      @points_won = 0
    end
  
    def win_point
      @points_won += 1
    end
  end

  class Game
    SCORE_NAMES = %w(Love Fifteen Thirty Forty)

    def initialize(player_1, player_2)
      @player_1 = player_1
      @player_2 = player_2
    end
  
    def score
      if @player_1.points_won >= 3 && @player_1.points_won == @player_2.points_won
        return "Deuce" 
      end

      if @player_1.points_won >= 4 || @player_2.points_won >= 4
        if (@player_1.points_won - @player_2.points_won).abs >=2
          return "#{leader.name} won the game!" 
        else
          return "Advantage #{leader.name}" 
        end
      end

      "#{SCORE_NAMES[@player_1.points_won]}, #{SCORE_NAMES[@player_2.points_won]}"
    end


  private

    def leader
      @player_1.points_won > @player_2.points_won ? @player_1 : @player_2
    end
  end
end

describe Tennis::Player do
  subject { Tennis::Player.new("Pete Sampras") }
  its (:name) { should eq "Pete Sampras" }
  its (:points_won) { should eq 0 }
  describe "#win_point" do
    before do
      subject.win_point
    end

    its (:points_won) { should eq 1 }

    context "after winning two more points" do
      before do
        2.times { subject.win_point }
      end

      its (:points_won) { should eq 3 }
    end
  end
end

describe Tennis::Game do
  subject { Tennis::Game.new(@player_1, @player_2) }
  before do
    @player_1 = Tennis::Player.new("Pete Sampras")
    @player_2 = Tennis::Player.new("Andre Agassi")
  end

  its (:score) { should eq "Love, Love" }

  context "when player 1 wins one point" do
    before do
      @player_1.win_point
    end
  
    its (:score) { should eq "Fifteen, Love" }
  end

  context "when player 2 wins three point" do
    before do
      3.times { @player_2.win_point }
    end
  
    its (:score) { should eq "Love, Forty" }
  end

  context "when player 1 wins 4 straight point" do
    before do
      4.times { @player_1.win_point }
    end
  
    its (:score) { should eq "Pete Sampras won the game!" }
  end

  context "when player 2 wins 4 straight point" do
    before do
      4.times { @player_2.win_point }
    end
  
    its (:score) { should eq "Andre Agassi won the game!" }
  end

  context "when each player wins three points" do
    before do
      3.times { @player_1.win_point }
      3.times { @player_2.win_point }
    end
  
    its (:score) { should eq "Deuce" }
  end

  context "when player 1 wins 3 points and player 2 wins 4 points" do
    before do
      3.times { @player_1.win_point }
      4.times { @player_2.win_point }
    end
  
    its (:score) { should eq "Advantage Andre Agassi" }
  
    context "after player 2 wins one more point" do
      before do
        @player_2.win_point
      end
  
      its (:score) { should eq "Andre Agassi won the game!" }
    end
  end
end