The previous test used a _SharedCache simulation that proved the atomic
swap pattern works but didn't exercise the real app.py code. This rewrite
imports app.py with AUTH_ENABLED=true, mocks SessionLocal and logger,
creates a real AuthManager user, and calls the actual _refresh_token_cache()
while concurrent readers access the actual _token_cache global.
7 tests: single row, multiple prefixes, empty DB, app.state sync, dirty
flag cleared, 4 concurrent readers x 100 refreshes (zero empty reads),
and 50 create/revoke churn cycles with concurrent readers.
Exercises the concurrent reader/writer scenario that the atomic swap
fix in app.py addresses. Uses a _SharedCache helper that mirrors the
module-level _token_cache global — both reader and writer access the
same .current reference, so the GIL-atomic swap is properly tested.
6 tests: swap correctness, concurrent readers (4 threads x 100 refreshes,
zero empty reads), app.state sync, multiple prefixes, empty DB, and
concurrent refresh from 4 threads.
isharak7m