ブロックの中身をテストするときのRSpecの書き方

block_spec.rb

class Sample
  def foo(x)
    ho = hoge(x) do |y|
      piyo(y)
    end
    ho + 'foo'
  end

  def hoge(x)
    yield x + 'hoge'
  end

  def piyo(y)
    y + 'piyo'
  end
end


describe Sample do
  it 'yields block of hoge method by passing block to stub' do
    allow(subject).to receive(:hoge).with('start') do |x, &block|
      expect(block.call(x)).to eq('startpiyo')
      'startpiyo'
    end
    subject.foo('start')
  end

  it 'yields block of hoge method by using `and_yield`' do
    allow(subject).to receive(:hoge).with('start').and_yield('yielded_arg')
    expect(subject.foo('start')).to eq('yielded_argpiyofoo')
  end
end

上記2つのどちらかの方法でテストする。

参考