[Housekeeping] Fix Unit Test Failure: Catastrophic failure: System.ArgumentOutOfRangeException

[TheCodeTraveler]

Description of Change

This PR fixes the ArgumentOutOfRangeException occurring in the Run All Unit Tests step of our Build Library (windows-latest) pipeline:

[xUnit.net 00:00:29.07] Catastrophic failure: System.ArgumentOutOfRangeException : Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')

The exception was happening because both MockPopup and MockPopupHandler were both calling HandlerCompleteTCS.SetResult(); in OnClosed causing a race condition where our test would sometimes fail and sometimes pass.

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard

Additional information

This PR updates the PopupTests to use Assert.ThrowsAnyAsync<OperationCanceledException>() which will pass when either an OperationCanceledException is thrown or an TaskCanceledException is thrown since TaskCanceledException derives from OperationCanceledException; Assert.ThrowsAnyAsync<T>() allows for derived types, whereas Assert.ThrowsAsync<T>() does not allow derived types.

This PR fixes an edge case where await popupDismissedTaskCompletionSource.Task.WaitAsync(token) does not throw a TaskCanceledException despite the token being canceled when HandlerCompleteTCS.Task had already completed; the fix is to manually add token.ThrowIfCancellationRequested(); in Popup.OnClosed().

This PR changes readonly IPopup poup -> readonly MockPopup popup because of the discrepancy between void IPopup.OnDismissedByTappingOutsideOfPopup() and the awaitable Task MockPopup.OnDismissedByTappingOutsideOfPopup(). I also added the missing await keyword when the tests call MockPopup.OnDismissedByTappingOutsideOfPopup().

This PR adds readonly MockPopupHandler popupHandler to PopupTests, and assigns this handler to readonly MockPopup popup in the constructor: popupHandler = CreateElementHandler<MockPopupHandler>(popup);

This PR also adds GitHubActionsTestLogger to provide us with more comprehensive logs when tests fail. This will help us solve test errors in the future.

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

[TheCodeTraveler]

@dotnet-policy-service agree

[ne0rrmatrix]

Looks like this solves a huge bug. Good job! It is nice to see this bug getting quashed. I had no idea what had been causing my builds to fail.