Bug: quickfiler-tests-depend-on-wall-clock-timing

[drmoisan]

• Work Mode: full-bug

Summary

Several QuickFiler.Test tests fail intermittently under load because they wait on real wall-clock time. Seen during parallel run bugs-2026-09-28:

• QfcDatamodelLivenessTests, including RemainingLoadActive_AcrossAsyncVoidFirstAwait_StaysTrueWhileLoaderProduces. Two failures stopped Bug: engine-toggle-prime-marker-registration-races-removal #944's P3-T8 gate, and one failure occurred during Bug: package-manifest-consistency-residuals #929's local run.
• QfcItemController.UiThreadDispatcherFixtureTests.Transaction_SecondCallerCannotInstallUntilTheFirstRestores, which failed once in CI on an earlier Bug: package-manifest-consistency-residuals #929 head.

Environment

• OS/version: Windows 11 (local, with concurrent coverage runs) and windows-latest (CI)
• Python version: n/a (C# / MSTest, parallel Workers=0, Scope=ClassLevel)
• Command/flags used: Invoke-MSTestWithCoverage.ps1, and the CI MSTest-with-coverage required check
• Data source or fixture: n/a

Steps to Reproduce

1. Run QuickFiler.Test under the parallel regime while the machine is loaded, for example with a second coverage run.
2. Observe intermittent failures in the tests named above.

Expected Behavior

The tests are deterministic regardless of machine load.

Actual Behavior

• QuickFiler.Test/Controllers/QfcDatamodelLivenessTests.cs uses SpinWait.SpinUntil(condition, TimeSpan.FromSeconds(5)) (line ~56) and .Task.Wait(TimeSpan.FromSeconds(5)) (lines ~103 and ~173). A slow scheduler turns these into assertion failures.
• QuickFiler.Test/Controllers/QfcItemController.UiThreadDispatcherFixtureTests.cs:206 fails intermittently. Its cause is not yet established.

Logs / Screenshots

• Attached minimal logs or screenshot
• Snippet: Bug: engine-toggle-prime-marker-registration-races-removal #944 evidence for P3-T8, first run; Bug: package-manifest-consistency-residuals #929 PR fix(929): remove altcover imports, correct SVGControl binding redirects, pass client-id to the repair workflow token step #949 CI history.

Impact / Severity

• Blocker
• High
• Medium
• Low

Source

From: docs/features/potential/2026-09-30-quickfiler-tests-depend-on-wall-clock-timing.md

[drmoisan]

Restoring sections dropped by the promotion tooling.

Suspected Cause / Notes

Real-time bounded waits violate the repository determinism rules: no wall-clock waits in tests, and use of FakeTimeProvider or a controllable scheduler.

• QfcDatamodelLivenessTests.cs uses SpinWait.SpinUntil(..., TimeSpan.FromSeconds(5)) (line ~56) and .Task.Wait(TimeSpan.FromSeconds(5)) (lines ~103 and ~173).
• The transaction test (QfcItemController.UiThreadDispatcherFixtureTests.cs:206) may be a different root cause. Triage it first, and split it into its own issue if its cause is not timing.

This hits a required check. #944 needed a one-time gate re-run because of it.

Proposed Fix / Validation Ideas

• Replace the bounded waits with deterministic completion signals (TaskCompletionSource or awaited handles) or an injected TimeProvider.
• Use no retries, [DoNotParallelize], Workers=1 or longer timeouts, and find any raced static state.
• Negative control: show that each rewritten test fails when the awaited signal is never set.