I fundamentally don’t think it’s a good pattern to have tests rely on your seed data, so I don’t want to sugar coat a path to encourage that. Of course, everyone can run their tests as they see fit, but Rails is not going to pave the road for you on approaches that aren’t deemed to be in the general interest.
So I don’t see us making changes either to the default test_helper.rb or providing something like fixtures_from_seeds. This smells like something that should live in an external gem.