- Add Library._make_table() override to automatically migrate genres when database schema is updated
- Migration splits comma/semicolon/slash-separated genre strings into genres list
- Writes changes to both database and media files with progress reporting
- Remove lazy migration from correct_list_fields() - now handled at database level
- Remove migration-specific tests (migration is now automatic, not lazy)
- Update changelog to reflect automatic migration behavior
Related PR review comment changes:
- Replace _is_valid with _filter_valid method in lastgenre plugin
- Use unique_list and remove genre field from Beatport plugin
- Simplify LastGenre tests - remove separator logic
- Document separator deprecation in lastgenre plugin
- Add deprecation warning for genre parameter in Info.__init__()
External Python packages interfacing beets may want to use an in-memory
beets library instance for testing beets-related code.
The `TestHelper` class is very helpful for this purpose.
Previously `TestHelper` was located in the `test/` directory.
Now it is part of `beets` itself (`beets.test.helper.TestHelper`) and
can be easily imported.
