fix: route around coveragepy#2124 flake in aio finalizer test - #3
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CI's pytest(3.11) job intermittently failed the 100%-coverage gate on the same two lines, reproduced live on GitHub Actions (~1-in-4 runs). Traced to an upstream coverage.py bug on Python 3.11 that loses trace lines right after awaiting a coroutine that cancels a task internally, which is exactly what grpc.aio's Server.stop() does. Adds a throwaway scheduling checkpoint so the tracer's blind spot lands there instead of the assertions under test.
The asyncio.sleep(0) checkpoint from the previous commit didn't work: it just relocated the tracer's blind spot onto the checkpoint line itself (confirmed by reproducing the flake again on CI), since the blind spot's width varies rather than being fixed at one line. Switch to marking the affected lines with pragma: no cover, which coverage.py resolves via static parsing rather than runtime tracing, so it's unaffected by the race.
13 consecutive clean pytest(3.11) runs on PR #3 after the pragma-exclusion fix, versus the original ~1-in-4 failure rate.
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Summary
pytest (3.11)job intermittently failed the 100%-coverage gate (~1-in-4 runs, reproduced live on GitHub Actions), always on the same two lines oftest_aio_app_finalizer_runs_on_root_close, despite all tests passing.CancelledError.grpc.aio'sServer.stop()does exactly that to its own background tasks.await asyncio.sleep(0)checkpoint right afterserver.stop(0)so the tracer's blind spot lands there instead of on the assertions under test.planning/changes/2026-07-13.01-aio-coverage-flake.mdandplanning/decisions/2026-07-13-coveragepy-2124-flake.mdfor full investigation and rejected alternatives.Test plan
just test-ci— 100% coverage, 27 passed, locallyjust lint-ci— clean