Jpa: generating test data from objects

We have dynamically generated dao classes for all tables in the database. Basically they do the same CRUD operations on their respective tables.

I want to see how I can test this generated code. The immediate idea is to populate some test data and run these CRUD operations. But being new to jpa / hiberate, I don't know how I can populate test data. I don't know the name of the table and fields. All I have is the dao library (I don't know the entity names as they are generated dynamically). Any testing approach would be much appreciated. TIA