In case you want to use the PATCH verbin Rack::Test and you get errors when you try it with the current gem release you will have to use the git version in your Gemfile:
group :test do
gem 'rack-test', :git => "https://github.com/brynary/rack-test.git"
While the PATCH verb has been included in a recent patch it's not yet in the gem release. Using the :git repo lets you test also PATCH routes for your rack app.