bla_controller.rb

class BlaController < ApplicationController                                                                                                                                                                                                    
                                                                                                                                                                                                                                               
  skip_before_filter :authenticate_user!                                                                                                                                                                                                       
                                                                                                                                                                                                                                               
  def index                                                                                                                                                                                                                                    
    render :nothing => true, :status => 200                                                                                                                                                                                                    
  end                                                                                                                                                                                                                                          
                                                                                                                                                                                                                                               
end

bla_controller_spec.rb

require 'spec_helper'                                                                                                                                                                                                                          
                                                                                                                                                                                                                                               
describe BlaController do                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
                                                                                                                                                                                                                                               
  it "should be able to puts response" do                                                                                                                                                                                                      
    get :index                                                                                                                                                                                                                                 
    puts response                                                                                                                                                                                                                              
  end                                                                                                                                                                                                                                          
end

test output.txt

...
200
{"Content-Type"=>"text/html; charset=utf-8"}
200
{"Content-Type"=>"text/html; charset=utf-8"}
200
{"Content-Type"=>"text/html; charset=utf-8"}
200
{"Content-Type"=>"text/html; charset=utf-8"}
200
{"Content-Type"=>"text/html; charset=utf-8"}
200
{"Content-Type"=>"text/html; charset=utf-8"}
  should be able to puts response (FAILED - 1)

Failures:

  1) BlaController should be able to puts response
     Failure/Error: Unable to find matching line from backtrace
     SystemStackError:
       stack level too deep
     # /usr/local/bin/ruby-1.9.3-p0/lib/ruby/gems/1.9.1/gems/activesupport-3.2.5/lib/active_support/core_ext/object/blank.rb:105

Finished in 2.54 seconds
1 example, 1 failure

Failed examples:

rspec ./spec/controllers/bla_controller_spec.rb:7 # BlaController should be able to puts response