ExecuteAsync_WhenFirstRefreshThrowsNonCancellationException_DoesNotFault
BackgroundService cancelled the service immediately after StartAsync, so
under parallel load the first RefreshAsync could be skipped (RefreshCallCount
0) and `await executeTask` rethrew TaskCanceledException before the IsFaulted
assertion. The test now waits for a TaskCompletionSource signal that the
first refresh was attempted before cancelling, and uses Task.WhenAny so a
Canceled ExecuteTask does not rethrow. Confirmed stable across full-suite
runs (408/408).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
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