Fix the Debounce component (#2759)

Author: dvoituron

src/Core/Utilities/InternalDebounce/DispatcherTimerExtensions.cs

@@ -35,22 +35,19 @@ public static TaskCompletionSource Debounce(this System.Timers.Timer timer, Func
         // If we're not in immediate mode, then we'll execute when the current timer expires.
         timer.Elapsed += Timer_Elapsed;
 
-        // Store/Update function
-        TimerDebounceItem updateValueFactory(System.Timers.Timer k, TimerDebounceItem v)
-        {
-            v.Status.SetCanceled();
-            v.Status = new TaskCompletionSource();
-            return v.UpdateAction(action);
-        }
-
         var item = _debounceInstances.AddOrUpdate(
                         key: timer,
                         addValue: new TimerDebounceItem()
                         {
                             Status = new TaskCompletionSource(),
                             Action = action,
                         },
-                        updateValueFactory: updateValueFactory);
+                        updateValueFactory: (k, v) =>
+                        {
+                            v.Status.SetCanceled();
+                            v.Status = new TaskCompletionSource();
+                            return v.UpdateAction(action);
+                        });
 
         // Start the timer to keep track of the last call here.
         timer.Start();
@@ -73,8 +70,27 @@ private static void Timer_Elapsed(object? sender, System.Timers.ElapsedEventArgs
 
             if (_debounceInstances.TryRemove(timer, out var item))
             {
-                _ = (item?.Action.Invoke());
-                item?.Status.SetResult();
+                if (item == null)
+                {
+                    return;
+                }
+
+                var task = item.Action.Invoke();
+                task.ContinueWith(t =>
+                {
+                    if (t.IsFaulted)
+                    {
+                        item.Status.SetException(t.Exception);
+                    }
+                    else if (t.IsCanceled)
+                    {
+                        item.Status.SetCanceled();
+                    }
+                    else
+                    {
+                        item.Status.SetResult();
+                    }
+                });
             }
         }
     }

tests/Core/Utilities/DebounceTests.cs

@@ -197,15 +197,35 @@ public async Task Debounce_Busy()
     [Fact]
     public async Task Debounce_Exception()
     {
-        // Act
-        Debounce.Run(50, async () =>
+        await Assert.ThrowsAsync<AggregateException>(async () =>
         {
-            await Task.CompletedTask;
-            throw new InvalidProgramException("Error");     // Simulate an exception
+            // Act
+            Debounce.Run(50, async () =>
+            {
+                await Task.CompletedTask;
+                throw new InvalidProgramException("Error");     // Simulate an exception
+            });
+
+            // Wait for the debounce to complete
+            await Debounce.CurrentTask;
         });
 
-        // Wait for the debounce to complete
-        await Debounce.CurrentTask;
+        // Assert
+        Assert.False(Debounce.Busy);
+    }
+
+    [Fact]
+    public async Task Debounce_AsyncException()
+    {
+        await Assert.ThrowsAsync<AggregateException>(async () =>
+        {
+            // Act
+            await Debounce.RunAsync(50, async () =>
+            {
+                await Task.CompletedTask;
+                throw new InvalidProgramException("Error");     // Simulate an exception
+            });
+        });
 
         // Assert
         Assert.False(Debounce.Busy);