Introduce flash messages (notice/alert/error) to the session then hit a path and assert it does (not) render the flash messages; capybara/rspec2/rails3.0

cached_pages_do_not_render_flash_spec.rb

#assumes use of capybara for request specs

require 'spec_helper'

describe "StaticPages" do
  class FlashController < ApplicationController
    def set_flash
      flash[:notice] = params[:message]
      flash[:error] = params[:message]
      flash[:alert] = params[:message]
      Rails.application.reload_routes!
      redirect_to params[:path]
    end
  end
  
  def set_flash_notice_and_redirect_to(message, path)
    YourApp::Application.routes.draw do
      match '/~set_flash' => "flash#set_flash", :defaults => {:path => path, :message => message}
    end
    visit "/~set_flash"
  end

  specify "should not render flash notices, since they will get cached" do
    begin
      set_flash_notice_and_redirect_to('foobar', '/')
      page.should_not have_content("foobar")
      set_flash_notice_and_redirect_to('foobar', some_path_which_renders_flash_messages)
      page.should have_content("foobar")
    ensure
      Rails.application.reload_routes!
    end
  end
end