DispatcherQueueTimerExtensions bug

[matheus-inacio]

Describe the bug

The Debounce extension method is not correctly updating the Action in the ConcurrentDictionary. This is causing the debounce extension to trigger the oldest version of the action in the 'chain' instead of the latest.

Steps to Reproduce

I've made a small test in order to confirm the bug:

[TestClass]
public class DebounceTests
{
	private static DispatcherQueueTimer _debounceTimer;
	private string _searchedTerm;
	private double _typingInterval = 200;

	[ClassInitialize]
	public static async Task InitializeAsync(TestContext context)
	{
		await ThreadHelper.ExecuteOnUIThread(() =>
		{
			_debounceTimer = DispatcherQueue.GetForCurrentThread().CreateTimer();
		});
	}

	private Task DelayAsync(double milliSeconds) => Task.Delay(TimeSpan.FromMilliseconds(milliSeconds));

	[TestMethod]
	public async Task ShouldTriggerTheLatestAction()
	{
		TriggerDebounce("T");
		await DelayAsync(_typingInterval);

		TriggerDebounce("Te");
		await DelayAsync(_typingInterval);

		TriggerDebounce("Tes");
		await DelayAsync(_typingInterval);

		TriggerDebounce("Test");

		await DelayAsync(800); // Waits debounce time

		_searchedTerm.Should().Be("Test"); // <- Is failing with "T"
	}

	private void TriggerDebounce(string value)
	{
		_debounceTimer.Debounce(() =>
			{
				_searchedTerm = value;
			},
			TimeSpan.FromSeconds(0.6));
	}
}

Expected behavior

As i understand, the debounce should trigger the latest Action passed to the method.

Screenshots

Test failing:

Environment

NuGet Package(s): v7.1.0
Package Version(s): v7.1.0

Windows 10 Build Number:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763)
• May 2019 Update (18362)
• May 2020 Update (19041)
• Insider Build ({build_number})

App min and target version:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763)
• May 2019 Update (18362)
• May 2020 Update (19041)
• Insider Build ({build_number})

[ghost]

Hello matheus-inacio, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[michael-hawker]

Nice catch @matheus-inacio, not sure how we haven't caught this. Mind adding your nice set of tests to our test suite as well for the future in your #4294 PR? Thanks!

[matheus-inacio]

Nice catch @matheus-inacio, not sure how we haven't caught this. Mind adding your nice set of tests to our test suite as well for the future in your #4294 PR? Thanks!

Done