问* ActionView::Helpers::ControllerHelper#response异常: RuntimeError委托给controller.response，但控制器为零

EN

*** RuntimeError Exception: ActionView::Helpers::ControllerHelper#response delegated to controller.response, but controller is nil: #<RSpec::Core::ExampleGroup::Nested_1::Nested_1::Nested_1:0x007faeb4852b08

class Api::V1::CatalogController < ApplicationController
  def search
    ...some stuff here...
    render json: {some_response}
  end
end

describe Api::V1::CatalogController do
  describe "searching" do
    before(:all) do
      @title = FactoryGirl.create(:title, {name: "Test Title"})
      @author = FactoryGirl.create(:author, last_name: "Smith")
      @edition = FactoryGirl.create(:edition, title: @title, writer_id: @author.id)
    end
    context "#search" do
      it "should return the given titles for a single word search" do
        get :search, {search_terms: {term: 'smith'}}
        expect(response).status.to eql(200)
        return_value.body.should == {titles: [@title]}
      end
    end
  end
end