2011/7/9 TDDBC Tokyo で高井さんに教えてもらいながら一緒に書いたコード

money.rb

# -*- coding: utf-8 -*-

class Money
  def initialize amount = 0
    @amount = amount
  end

  def to_i
    @amount
  end

  YEN_10000 = Money.new 10000
  YEN_5000  = Money.new 5000
  YEN_2000  = Money.new 2000
  YEN_1000  = Money.new 1000
  YEN_500   = Money.new 500
  YEN_100   = Money.new 100
  YEN_50    = Money.new 50
  YEN_10    = Money.new 10
  YEN_5     = Money.new 5
  YEN_1     = Money.new 1

end

class VendingMachine
  attr_reader :posted_total
  attr_accessor :randomizer

  def initialize
    @posted_total = 0
    @stock = Hash.new
    @randomizer = -> { rand(100) <= 5 }
  end

  def post money
    case money.to_i
    when 1, 5, 2000, 5000, 10000
      raise
    else
      @posted_total += money.to_i
    end
  end

  def add_stock item, num
    @stock[item.id] = [item, num]
  end

  def purchasable_ids
    ret = []
    @stock.each do |id, pair|
      item, num = pair
      if @posted_total > item.price
        ret << item.id
      end
    end
    ret
  end

  def sell_item id
    item, num = @stock[id]
    sn = unless num == 1
           @randomizer.call ? 2 : 1
         else
           1
         end

    if (num - sn) >= 0
      @stock[id] = [item, num - sn]
    else
      raise
    end
  end

  def num_stock
    @stock.inject(0) do |r, ary|
      r += ary.last.last
    end
  end
end

class Item
  attr_accessor :id
  attr_accessor :name
  attr_accessor :price

  def initialize id, name, price
    @id = id
    @name = name
    @price = price
  end

end

money_spec.rb

# -*- coding: utf-8 -*-

require 'vending_machine'

describe Money do
  context "1000円札" do # thousand_yen_bill
    describe "#initialize" do

      it "初期化" do
        Money::YEN_1000.should be_kind_of Money
        Money::YEN_1000.to_i.should eql 1000
      end

    end
  end
end

describe VendingMachine do
  context "自動販売機" do
    before do
      @vm = VendingMachine.new
    end
    describe "#posted_total" do
      it "投入金額が返ること" do
        @vm.posted_total.should eql 0
      end
    end
    describe "#post" do
      it "お金を投入できる" do
        tyb = Money::YEN_1000
        @vm.post(tyb)
        @vm.posted_total.should eql 1000
      end
      it "1円を投入できない" do
        oyc = Money::YEN_1
        lambda{@vm.post(oyc)}.should raise_exception
      end
      it "5円を投入できない" do
        fyc = Money::YEN_5
        lambda{@vm.post(fyc)}.should raise_exception
      end
    end

    describe "#num_stock" do
      it "在庫数が算出される" do
        @vm.num_stock.should eql 0
      end
    end
    context "在庫が１この場合" do
      before do
        cola = Item.new(1, 'コーラ',120)
        @vm.add_stock(cola, 1)
      end
      it "あたりが出ない" do
        @vm.randomizer = -> {true}
        @vm.post Money::YEN_1000
        @vm.sell_item 1
        @vm.num_stock.should eql 0
     end
    end
    context "在庫が5個ある場合" do
      before do
        cola = Item.new(1, 'コーラ',120)
        @vm.add_stock(cola, 5)
      end
      describe "#add_stock" do
        it "在庫が追加できる" do
          @vm.num_stock.should eql 5
        end
      end
      describe "#purchasable_ids" do
        it "現在買える商品のIDのリストが返る" do
          @vm.purchasable_ids.should eql []
          @vm.post Money::YEN_100
          @vm.purchasable_ids.should eql []
          @vm.post Money::YEN_100
          @vm.purchasable_ids.should eql [1]
        end
      end
      describe "#sell_item" do
        it "商品を買える" do
          @vm.randomizer = -> {false}
          @vm.post Money::YEN_1000
          @vm.sell_item 1
          @vm.num_stock.should eql 4
        end
        it "あたりがでる" do
          @vm.randomizer = -> {true}
          @vm.post Money::YEN_1000
          @vm.sell_item 1
          @vm.num_stock.should eql 3
         end
      end
    end

    describe "#change_total" do
      it "お釣り用の総額を"
    end

  end

end