After setting up the correct package imports and exports in the manifest (if you haven't already), the easiest thing to start with would probably be using my quickstart [1] as a basis for testing various search features. Make the entity indexed, add commands to get stimulate adequate coverage of "core" features, etc. That will typically start you down the rabbit hole of necessary fixes.

The biggest challenge always seems to be ClassLoader issues, but address those as they come up.

Let me know what you'd like help with! I've considered pulling the Arquillian tests out of ORM all together and instead setting up an "Hibernate OSGi Integration Test Suite" project for ORM, Search, Validator, etc., hooked up to CI. Once we progress, it might be worth discussing.