The PR #909 data-safe-update tests passed in isolation but failed only in
full-suite CI order. Two independent, order-dependent leaks were at play:
1. Module-identity leak (the #878/#894 class). The `isolated_db`/`fresh_app`/
`fresh_resolver` fixtures in tests/backend/** purge `core.*`/`services.*`
from `sys.modules` and never restore them, so `sys.modules["core.db"]`
afterward is a DIFFERENT object than the one the migration-safety tests
imported at collection. `monkeypatch.setattr("core.db.DB_PATH", ...)`
re-resolved the dotted string to the re-imported module, while
`_run_alembic_upgrade`/`init_db` (bound at collection) kept reading the
ORIGINAL module's globals — so the patch missed and the upgrade ran against
the ambient session DB. Result: no backup at the asserted path, and the
mid-flight-failure injection never hit the expected DB (DID NOT RAISE).
The same divergence hit the lazy `from core import db_backup` inside
`_run_alembic_upgrade`, so patching `MAX_BACKUP_DB_BYTES` was silently lost.
2. Logger-disable leak. Alembic's env.py called `fileConfig(...)` with the
default `disable_existing_loggers=True`, which disabled the already-created
`omnivoice.db.backup` logger the first time any earlier test ran a real
`alembic upgrade` — so the oversized-DB "Skipping pre-migration DB backup"
line was never emitted and the caplog assertion failed. This also silently
mutes the live app's logging after a real startup migration.
Fixes:
- env.py: `fileConfig(..., disable_existing_loggers=False)` so a migration
never mutes the app's (or another test's) loggers.
- core/db.py: import `db_backup`/`APP_VERSION` at module level so
`_run_alembic_upgrade` uses a stable reference immune to a `sys.modules`
purge, matching what tests patch at collection.
- test_db_migration_safety.py: patch DB_PATH on the imported `core.db` module
object rather than the re-resolvable dotted string — the correct,
self-contained seam.
Verified: the four migration-safety tests + the oversized-backup test pass in
full-suite order and in isolation; full `pytest tests/` is green
(2206 passed, 0 failed).
Co-authored-by: mergetest <test@local>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
