Rspec：如何测试控制器的around_action过滤器？

Question

My controller has an around_action filter on its update action, to trigger specific behavior if a particular attribute is updated. Something like below:

class EventsController < ApplicationController
  around_action :contact_added_users

  def contact_added_users
    @event = Event.find(params[:id])
    existing_users = @event.users
    yield
    added_users = @event.users.reject{|u| existing_users.include? u }
    added_users.each { |u| u.contact }
  end
end

I've verified that it works manually, but how can I test my around_action filter in Rspec? I've tried something like:

describe EventsController do
  describe "PUT update" do
    let(:event) { FactoryGirl.create(:event) }
    let(:old_u) { FactoryGirl.create(:user) }
    let(:new_u) { FactoryGirl.create(:user) }
    before(:each) { event.users = [ old_u ]
                    event.save }

    context "when adding a user" do
      it "contacts newly added user" do
        expect(new_u).to receive(:contact)
        expect(old_u).not_to receive(:contact)

        event_params = { users: [ old_u, new_u ] }
        put :update, id: event.id, event: event_params
      end
    end

...but it fails. Also tried adding

    around(:each) do |example|
      EventsController.contact_added_users(&example)
    end

but still no dice. How can I test this correctly?

Answer 1

I'd suggest stubbing the call to Event and returning a double that can respond to :users with the results you need for the spec to pass. The trick is that :users must be called twice with different results. RSpec allows you to pass a list of values that will be returned for successive calls:

let(:existing_users) { [user_1, user_2] }
let(:added_users) { [user_3] }
let(:event) { double('event') {

before(:each) do
  Event.stub(:find).with(params[:id]) { event }
  event.should_receive(:users).exactly(2).times.and_return(existing_users, added_users)
end