block4.rb

describe Post do
  let(:api_client) { double(fetch_comments: []) }
  subject(:post) { Post.new(api_client: api_client) }

  def fetch_comments_with(params)
    receive(:fetch_comments).with(a_hash_including(params)).once
  end

  describe '#comments' do
    it 'only fetches the approved comments by default' do
      expect(api_client).to fetch_comments_with(approved: true)

      post.comments
    end

    it 'only fetches the unread comments by default' do
      expect(api_client).to fetch_comments_with(status: :unread)

      post.comments
    end
  end
end