as I can remember the problem was with environment, as I can remember the default persistence.xml profile for unittests is production, and if you changed something in the development - that wouldn't be available at tests. look at the build.xml and change it to deploying your current
workingprofile, or simply move your configuration across of profiles.
That didn't work out at all, the reference to entityManager is not bound however the reference to the DefaultDS exists. I have tried to update the test configuration to match Dan's proposal but still I got the exception others have gone through.