I’m working on a project right now where I’m running Cucumber tests. As part of my Cucumber features I’m checking the validity of the XHTML markup with a special step definition sprinkled throughout my scenarios. As part of that the markup_validity gem is included to perform the actual validation. When I started adding RDFa to my pages the markup of course no longer validated. I had the choice of either forgoing validating as part of my Cucumber tests and testing markup validity some other way or adding RDFa support to markup_validity. It was simple enough to fork the markup_validity github project, add support for XHTML+RDFa, and get my tests passing again. After a few corrections, Aaron Patterson (of Nokogiri fame) accepted my changes into trunk, re-released the gem and added me as a collaborator on the github project.

If you need to validate your XHTML+RDFa markup as part of your test/unit or rspec tests, please give it a try and let me know if it works for you:

gem install markup_validity

If you uninstall the sources gem that rubygems relies on you’ll get an awful error if you try to run gem. And since sources-0.0.1 is probably best installed as a gem well… you get the picture.
If you accidentally uninstall the sources gem, create a file named sources.rb and place the following inside:

module Gem
@sources = ["http://gems.rubyforge.org"]
def self.sources
@sources
end
end

I was then able to reinstall the sources gem and be back in business.