expectations

Rubyの新しいテスティングフレームワークのひとつ。最小主義なのが特徴でコンパクトでエレガントにテストが記述できる。作者Jay Fields氏のユニットテストの信念がとてもよく現れている。

• ひとつの文法しか用意していない。assertionのメソッドを使い分けなくてすむ。
• 『one assertion per test』という考え方を強制している。ひとつのテストにはひとつのassertion。だからこそ、一度のテストですべてのassertionを実行してくれる。
• setupとteardownがないので初期化や後片付けもテストメソッドの中に記述する。DRY原則…そんなの関係ねぇ！
• Mochaというモックフレームワークとの連携がとれているので、振舞いベースのテストも同じ文法で書ける。
• テストが明確なのでテスト名すらない。

インストール

$ gem install expectations

記述例

READMEより抜粋。

中のexpectメソッドの引数が空気を読んでくれるため、コンパクトに書ける。

require File.dirname(__FILE__) + "/test_helper"

Expectations do
  
  # State based expectation where a value equals another value
  expect 2 do
    1 + 1
  end
  
  # State based expectation where an exception is expected. Simply expect the Class of the intended exception
  expect NoMethodError do
    Object.no_method
  end
  
  # Behavior based test using a traditional mock
  expect mock.to.receive(:dial).with("2125551212").times(2) do |phone|
    phone.dial("2125551212")
    phone.dial("2125551212")
  end

  # Behavior based test using a stub
  expect stub.to.receive(:dial).with("2125551212").times(2) do |phone|
    phone.dial("2125551212")
    phone.dial("2125551212")
  end

  # Behavior based test using a stub_everything
  expect stub_everything.to.receive(:dial).with("2125551212").times(2) do |phone|
    phone.dial("2125551212")
    phone.dial("2125551212")
  end

  # Behavior based test on a concrete mock
  expect Object.to.receive(:deal) do
    Object.deal
  end
  
  # State based test utilizing a stub
  expect 2 do
    stub(:two => 2).two
  end
  
  # State based test utilizing a concrete mock
  expect 2 do
    Object.expects(:bar).returns 2
    Object.bar
  end
  
  # Behavior based test utilizing a stub and a concrete mock
  expect 1 do
    Object.expects(:give_me_three).with(3).returns 1
    Object.give_me_three(stub(:three=>3).three)
  end
  
  # State based test matching a Regexp
  expect /a string/ do
    "a string"
  end
  
  # State based test checking if actual is in the expected Range
  expect 1..5 do
    3
  end
  
  # State based test to determine if the object is an instance of the module
  expect Enumerable do
    []
  end

  # State based test to determine if the object is an instance of the class
  expect String do
    "a string"
  end
  
  # State based test to determine if the modules are the same
  expect Enumerable do
    Enumerable
  end
  
  # State based test to determine if the classes are the same
  expect String do
    String
  end
  
  # State based test with XML strings, whitespace between tags is ignored
  expect xml("<a><foo>bar</foo></a>") do
    "<a>\n\t<foo>bar</foo>  \n</a>"
  end
  
  # State based test with XML strings, whitespace between tags is ignored
  expect xml(<<-eos) do
    <one>
      <two>
        <three>4</three>
        <five> 6 </five>
      </two>
    </one>
    eos
    "<one><two><three>4</three>
      <five> 6 </five>
    </two></one>"
  end

  # this is normally defined in the file specific to the class
  klass = Class.new do
    def save(arg)
      record.save(arg)
    end
  end
  # State based delegation test
  expect klass.new.to.delegate(:save).to(:record) do |instance|
    instance.save(1)
  end
  
  # this is normally defined in the file specific to the class
  klass = Class.new do
    attr_accessor :started
  end
  # State based fluent interface boolean test using to be
  expect klass.new.to.be.started do |process|
    process.started = true
  end
  
  # this is normally defined in the file specific to the class
  klass = Class.new do
    attr_accessor :finished
  end
  # State based fluent interface boolean test using to have
  expect klass.new.to.have.finished do |process|
    process.finished = true
  end
  
end