registrations_controller.rb

class RegistrationsController < Devise::RegistrationsController
  before_filter :check_presence_of_plan_id_and_campaign_id, :only => [ :new, :create ]

  protected

    def check_presence_of_plan_id_and_campaign_id
      redirect_to plans_url if cookies[:plan_id].blank? || cookies[:campaign_id].blank?
    end
end

registrations_controller_spec.rb

require 'spec_helper'

describe RegistrationsController, 'create the first user account' do
  context "when there isn't plan_id in the cookies" do
    it 'should redirect to the plans page' do
      cookies[:campaign_id] = '1'
      get :new

      response.should redirect_to(plans_url)
    end
  end
end

routes.rb

Pfr::Application.routes.draw do
  resources :campaigns
  resources :plans

  devise_for :users, :controllers => { :registrations => 'registrations' }, :skip => [ :sessions ]

  as :user do
    get     "/sign_in"  => "devise/sessions#new", :as => :new_user_session
    post    "/sign_in"  => "devise/sessions#create", :as => :user_session
    delete  "/sign_out" => "devise/sessions#destroy", :as => :destroy_user_session
    get     "/users/cancel" => "devise/registrations#cancel", :as => :cancel_user_registrations
    post    "/users" => "registrations#create", :as => :user_registration
    get     "/sign_up" => "registrations#new", :as => :new_user_registration
    get     "/users/edit" => "devise/registrations#edit", :as => :edit_user_registration
    put     "/users" => "devise/registrations#update"
    delete  "/users" => "devise/registrations#destroy"
  end

  root :to => "home#index"
end

spec_helper.rb

require 'rubygems'
require 'spork'
require 'devise/test_helpers'

RSpec.configure do |config|
  config.before(:suite) do
    DatabaseCleaner.strategy = :truncation
  end

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end

  config.include Devise::TestHelpers, :type => :controller
end

ENV["RAILS_ENV"] ||= 'test'
require File.expand_path("../../config/environment", __FILE__)
require 'rspec/rails'

# Requires supporting ruby files with custom matchers and macros, etc,
# in spec/support/ and its subdirectories.
#Dir[Rails.root.join("spec/support/**/*.rb")].each {|f| require f}

RSpec.configure do |config|
  config.mock_with :rspec
end

ActiveSupport::Dependencies.clear
ActiveRecord::Base.instantiate_observers

FactoryGirl.factories.clear
Pfr::Application.reload_routes!