follow_redirect

# File actionpack/lib/action_controller/test_process.rb, line 408
    def follow_redirect
      redirected_controller = @response.redirected_to[:controller]
      if redirected_controller && redirected_controller != @controller.controller_name
        raise "Can't follow redirects outside of current controller (from #{@controller.controller_name} to #{redirected_controller})"
      end

      get(@response.redirected_to.delete(:action), @response.redirected_to.stringify_keys)
    end