ARID ( ActiveResourceIntegrationDsl ) is a Ruby on Rails plugin offering easy to use methods for writing integration tests on RESTful Rails apps. With ARID you write simple statements like user.builds_article(:params => {:article => {:subject => 'Hey!', :content => 'Hello World!'}}) which will GET your new_article_path, check that it has a properly formatted form with fields for all the given params, and then will POST the params to articles_path and assert the expected response. You can even pass a block to the above call to perform additional tests. And YES, ARID tests AJAX calls.
More info and installation instructions at http://arid.rubyforge.org.
