stubbing devise authentication

controller_helpers.rb

  module ControllerHelpers
    def sign_in(user = double('user'))
      if user.nil?
        allow(request.env['warden']).to receive(:authenticate!).and_throw(:warden, {:scope => :user})
        allow(controller).to receive(:current_user).and_return(nil)
      else
        allow(request.env['warden']).to receive(:authenticate!).and_return(user)
        allow(controller).to receive(:current_user).and_return(user)
      end
    end
  end

  RSpec.configure do |config|
    config.include Devise::TestHelpers, :type => :controller
    config.include ControllerHelpers, :type => :controller
  end