How unit indicates which tables (part of schema) should be created for
They don't - all tables are made available to the tests.
Also, I guess that for many tests empty schema is not
enough, one probably should provide some pre-defined values for table
row fields. @group Database is not enough for that.
This is possible, in which case your particular test first needs to populate the db. Be sure to use the proper abstraction layers for this - I've seen people write tests that break encapsulation badly and then break as soon as you change a bit around somewhere.
Jeroen De Dauw
Don't panic. Don't be evil.