テスト駆動開発入門をRubyで写経してみた。10

10章で実施したこと

• *()メソッドをMoneyクラスに移動

結局Pythonの__repr__()メソッドに相当するメソッドが分かりませんでした。to_s()メソッドがクラスの文字列表現らしいのですが、うまく出力してくれませんでした。

money.rb

#!/usr/bin/ruby
#coding: utf-8
# テスト駆動開発入門10章 興味深い時(times)
class Money
  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 self.franc(amount)
    return Franc.new(amount, "CHF")
  end

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

class Dollar < Money
end

class Franc < Money
end

money_test.rb

#!/usr/bin/ruby
#coding: utf-8
# テスト駆動開発入門10章 興味深い時(times)
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.franc(5)  == Money.franc(5))
    assert(Money.franc(5)  != Money.franc(6))
    assert(Money.dollar(5) != Money.franc(5))
  end

  def test_Franc_multiplication
    five = Money.franc(5)
    assert_equal(Money.franc(10), five * 2)
    assert_equal(Money.franc(15), five * 3)
  end

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

  def test_different_class_equarity
    assert(Money.new(10, "CHF") == Franc.new(10, "CHF") )
  end
end