Added observe exceptions extensions for tasks

Author: jamesmcroft

src/MADE.Threading/TaskExtensions.cs

@@ -0,0 +1,52 @@
+// MADE Apps licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace MADE.Threading
+{
+    using System;
+    using System.Threading.Tasks;
+
+    /// <summary>
+    /// Defines a collection of extensions for tasks.
+    /// </summary>
+    public static class TaskExtensions
+    {
+        /// <summary>
+        /// Observes the exceptions of faulted tasks.
+        /// </summary>
+        /// <param name="task">The task to observe for exceptions.</param>
+        /// <param name="onException">An action invoked when an exception is caught.</param>
+        /// <returns>An asynchronous operation.</returns>
+        public static Task AndObserveExceptions(this Task task, Action<Exception> onException = null)
+        {
+            task?.ContinueWith(
+                t =>
+                {
+                    AggregateException aggregateException = t.Exception?.Flatten();
+                    onException?.Invoke(aggregateException);
+                },
+                TaskContinuationOptions.OnlyOnFaulted);
+
+            return task;
+        }
+
+        /// <summary>
+        /// Observes the exceptions of faulted tasks.
+        /// </summary>
+        /// <param name="task">The task to observe for exceptions.</param>
+        /// <param name="onException">An action invoked when an exception is caught.</param>
+        /// <returns>An asynchronous operation.</returns>
+        public static Task<T> AndObserveExceptions<T>(this Task<T> task, Action<Exception> onException = null)
+        {
+            task?.ContinueWith(
+                t =>
+                {
+                    AggregateException aggregateException = t.Exception?.Flatten();
+                    onException?.Invoke(aggregateException);
+                },
+                TaskContinuationOptions.OnlyOnFaulted);
+
+            return task;
+        }
+    }
+}