テスト駆動開発入門をRubyで写経してみた。12

12章で実施したこと

• Expressionインタフェースの追加
• +()メソッドの追加
• Bankクラスの仮実装

money.rb

静的型付けであるJavaのコードから写経しているので、不自然な部分が多々あります。、

#!/usr/bin/ruby
#coding: utf-8
# テスト駆動開発入門12章 ついに加法
class Expression
end

class Money < Expression
  attr_accessor :amount, :currency
  protected :amount

  def initialize(amount, currency)
    @amount = amount
    @currency = currency
  end

  def ==(other)
    return @amount == other.amount && \
        @currency == other.currency
  end

  def *(multiplier)
    return Money.new(@amount * multiplier, @currency)
  end

  def +(addend)
    return Money.new(@amount + addend.amount, @currency)
  end

  def self.franc(amount)
    return Money.new(amount, "CHF")
  end

  def self.dollar(amount)
    return Money.new(amount, "USD")
  end
end

class Bank
  def reduce(source, currency_to)
    return Money.dollar(10)
  end
end

money_test.rb

#!/usr/bin/ruby
#coding: utf-8
# テスト駆動開発入門12章 ついに加法
require 'test/unit'
require 'money'

class TestMoney < Test::Unit::TestCase
  def test_multiplication
    five = Money.dollar(5)
    assert_equal(Money.dollar(10), five * 2)
    assert_equal(Money.dollar(15), five * 3)
  end

  def test_equality
    assert(Money.dollar(5) == Money.dollar(5))
    assert(Money.dollar(5) != Money.dollar(6))
    assert(Money.dollar(5) != Money.franc(5))
  end

  def test_currency
    assert_equal("USD", Money.dollar(1).currency)
    assert_equal("CHF", Money.franc(1).currency)
  end

  def testSimpleAddition
    five = Money.dollar(5)
    sum = five + five
    bank = Bank.new()
    reduced = bank.reduce(sum, "USD")
    assert_equal(Money.dollar(10), reduced)
  end
end

money_test1.9.rb

minitest/unitバージョンも書いてみました。
違いといえば、MiniTest::Unit.autorunの追加と継承するクラスが違うくらいですかね。シンプルな使い方しかしていないので、書き方にあまり差異がありません。

#!/usr/bin/ruby
#coding: utf-8
# テスト駆動開発入門12章 ついに加法
require 'minitest/unit'
require 'money'

MiniTest::Unit.autorun

class TestMoney < MiniTest::Unit::TestCase
  def test_multiplication
    five = Money.dollar(5)
    assert_equal(Money.dollar(10), five * 2)
    assert_equal(Money.dollar(15), five * 3)
  end

  def test_equality
    assert(Money.dollar(5) == Money.dollar(5))
    assert(Money.dollar(5) != Money.dollar(6))
    assert(Money.dollar(5) != Money.franc(5))
  end

  def test_currency
    assert_equal("USD", Money.dollar(1).currency)
    assert_equal("CHF", Money.franc(1).currency)
  end

  def testSimpleAddition
    five = Money.dollar(5)
    sum = five + five
    bank = Bank.new()
    reduced = bank.reduce(sum, "USD")
    assert_equal(Money.dollar(10), reduced)
  end
end