设我们有

# app/controllers/posts_controller.rb
class PostsController
  def create
  end

  def index
  end
end

# spec/controllers/posts_controller_spec.rb
describe PostsController do
  describe :index do
    before do
      post :create content: 'Lorem lipsm'
      get :index
    end

    expect(respond).to be_success
  end
end

若观察 log/test.rb, 会发现 GET posts#index的参数里有POST posts#create时的content, 原因是什么呢？