As described in the last bullet of section "Making Changes" in the HowToContribute doc ( http://wiki.apache.org/pig/HowToContribute ), Pig does (or is supposed to ) support the following command for running an individual testcase class,
ant test -Dtestcase=<ClassName> (For example ant test -Dtestcase=TestPigFile)
although it was not working last I checked. Personally, I would prefer it this way since this command conforms to what Hadoop uses to achieve the same purpose. To make work, what we need to do is just port the same functionality from Hadoop's build.xml to Pig's build.xml.
So if there is no objections, either Stefan (since Stefan has been doing a great job on this already) or myself can start making the above command work as expected.