bowling_game_spec.rb

# coding: utf-8

class Game

  def initialize
    @rolls = []
  end

  def roll(pins)
    @rolls << pins
  end

  def score
    roll_idx = 0
    score = 0
    10.times do |frame|
      if strike?(roll_idx)
        score += strike_bonus(roll_idx)
        roll_idx += 1
      elsif spare?(roll_idx)
        score += spare_bonus(roll_idx)
        roll_idx += 2
      else
        score += score_of_rame(roll_idx)
        roll_idx += 2
      end
    end
    score
  end

  private

  def strike?(roll_idx)
    @rolls[roll_idx] == 10
  end

  def spare?(roll_idx)
    @rolls[roll_idx] + @rolls[roll_idx+1] == 10
  end

  def score_of_rame(roll_idx)
    @rolls[roll_idx] + @rolls[roll_idx + 1]
  end

  def strike_bonus(roll_idx)
    10 + @rolls[roll_idx + 1] + @rolls[roll_idx + 2]
  end

  def spare_bonus(roll_idx)
    10 + @rolls[roll_idx + 2]
  end

end

describe Game do
  before :each do
    @game = Game.new
  end

  specify "すべてガターの場合スコアは0点" do
    20.times { @game.roll 0 }
    @game.score.should == 0
  end
end

private

def roll_gutter
  game.roll 0
end

def roll_strike
  game.roll 10
end

def roll_spare
  game.roll 5; game.roll 5
end

public


describe Game do
  let(:game) { Game.new }

  context "すべて1ピンの場合" do
    before do
      20.times { game.roll 1 }
    end

    it "スコアは20点" do
      game.score.should == 20
    end
  end

  subject { game.score }

  context "ストライクの場合" do
    before do
      roll_strike
      game.roll 3
      game.roll 4 # 24
      18.times { roll_gutter }
    end

    it "スコアは24点" do
      should == 24
    end
  end

  context "パーフェクトゲームの場合" do
    before do 12.times { roll_strike } end
    it { should == 300 }
  end

  context "スペアの場合" do
    before do
      roll_spare
      game.roll 4
      game.roll 3 # 21
      16.times { roll_gutter }
    end

    it { should == 21 }
  end

  context "Uncle Bobの受け入れゲームの場合" do
    # [1,4,4,5,6,4,5,5,10,0,1,7,3,6,4,10,2,8,6] => 133
    before do
      [1,4,4,5,6,4,5,5,10,0,1,7,3,6,4,10,2,8,6].each { |pins| game.roll pins }
    end

    it { should == 133 }
  end
end