Jpa: Generating test data from entities

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

I'm looking to see how I can test this generated code. Immediate idea is to populate some test data and launch these CRUD operations. But being new to jpa/hiberate, I have no clue how I can populate test data. I neither know the table name nor the fields. All I have is the dao library (I don't know the entity names either as they are generated dynamically). Any approach on testing would be much appreciated. TIA