It isn't used in the committed tests. I've used it locally to run the CDI integration tests in form of a JAR on Weld (because they'll fail on AS). I've created a "weld" profile in the tck-runner project for that locally. It didn't make really much sense to commit the weld profile, though, since it can't be used with the web archives we normally create for the tests. Bottom-line is, this builder can help in certain situations, but is not actively used in the tests right now.