pg_cron: say where an undeclared queue came from

[marcgibbons]

When a schedule's queue is not declared, the message names a queue the user may never have typed:

queue 'reports' is not declared.

validate_declared_queue resolves the effective queue — the explicit override if given, else the task's own queue_name — then reports whichever it landed on. In the admin create form queue is not a field (it is resolved from the task), so the error is re-homed onto the form as a non-field error. The result is a form with no queue input, failing over a queue name that came from a decorator the message never mentions, with no statement of what to do about it.

This is the common case, not an edge one: any task whose queue_name falls outside a narrowed QUEUES hits it — see tests/pg_cron/test_admin/test_scheduledtask.py:211.

Ship

Make the message carry provenance and a resolution, distinguishing the two paths that reach it:

• explicit override (queue given on the schedule) — the user chose it; the current wording is fine
• derived from the task — say so, and name the fix: declare the queue in OPTIONS["QUEUES"], or set an override

Both callers benefit: ScheduledTask.clean (via validate_queue_against_backend) and the absurd.E007 schedule check at django_absurd/checks.py:323. Keep this project's msg/hint split on the check path — the problem in msg, the resolution in hint.

Source: django_absurd/pg_cron/validators.py:52.

Note for whoever picks it up

Several tests assert the current text and will need updating — tests/pg_cron/test_pg_cron_checks.py (including queue '' is not declared for an empty override), test_scheduler_app_checks.py:83, test_admin/test_scheduledtask.py:233 and :258, validators/test_declared_queue.py:20. That empty-override case is worth its own wording: queue '' is not declared reads as a bug in the message rather than a statement about the config.

Supersedes the original scope of this issue (a check for a backend declaring no queues), which needed a deliberate QUEUES: [] plus the pg_cron app — too narrow to warrant a check ID, while the misleading message affects every undeclared-queue case.