关于capybara ，rspec 测试rails3.2不能渲染view 的问题
https://www.relishapp.com/rspec/rspec-rails/v/2-8/docs/controller-specs/render-views

http://stackoverflow.com/questions/4706370/rspec-view-testing-with-capybara-and-rails3/4773050#4773050#
http://blog.chrisblunt.com/testing-rendered-views-with-rspec2-capybara-a