Add --exit option to migration generator

[zimt28]

Would make sense to add an --exit option to Mix.Tasks.AshPostgres.GenerateMigrations? It could then be used in CIs and fail if resources and migrations don't fit together. The big issue I see here is that the CI would have to be changed every time there's a new api.

[zimt28]

--exit might not be the best name though. Maybe --enforce-latest-migrations?
This is how other libraries do it:

[
  "format --check-formatted",
  "credo --strict",
  "sobelow --exit",
  "dialyzer --halt-exit-status"
]

[zachdaniel]

Yeah, I think ash_postgres.generate_migrations --check-generated would be a good name for the flag. We'd then just have to add a check after we've generated a full list of "operations" and if there are any, check the --check-generated flag and bail if that is set.

[zachdaniel]

A good idea :)

[zimt28]

This has been added via #43 ✅