From 5eb9c25574671a8a4bdd4901343fbb938d0ddb6a Mon Sep 17 00:00:00 2001
From: Ben Adams <thundercat@illyriad.co.uk>
Date: Mon, 13 Nov 2017 12:14:12 +0000
Subject: [PATCH] AggregateException

---
 src/Ben.Demystifier/ExceptionExtentions.cs    |  9 ++
 .../AggregateException.cs                     | 88 +++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 test/Ben.Demystifier.Test/AggregateException.cs

diff --git a/src/Ben.Demystifier/ExceptionExtentions.cs b/src/Ben.Demystifier/ExceptionExtentions.cs
index f14ee45..b4ab1b9 100644
--- a/src/Ben.Demystifier/ExceptionExtentions.cs
+++ b/src/Ben.Demystifier/ExceptionExtentions.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Ben A Adams. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic.Enumerable;
 using System.Reflection;
 
 namespace System.Diagnostics
@@ -20,6 +21,14 @@ namespace System.Diagnostics
                     stackTraceString.SetValue(exception, stackTrace.ToString());
                 }
 
+                if (exception is AggregateException aggEx)
+                {
+                    foreach (var ex in EnumerableIList.Create(aggEx.InnerExceptions))
+                    {
+                        ex.Demystify();
+                    }
+                }
+
                 exception.InnerException?.Demystify();
             }
             catch
diff --git a/test/Ben.Demystifier.Test/AggregateException.cs b/test/Ben.Demystifier.Test/AggregateException.cs
new file mode 100644
index 0000000..a33d319
--- /dev/null
+++ b/test/Ben.Demystifier.Test/AggregateException.cs
@@ -0,0 +1,88 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Demystify
+{
+    public class AggregateException
+    {
+        [Fact]
+        public void DemystifiesAggregateExceptions()
+        {
+            Exception demystifiedException = null;
+
+            try
+            {
+                var tasks = new List<Task>
+                {
+                    Task.Run(async () => await Throw1()),
+                    Task.Run(async () => await Throw2()),
+                    Task.Run(async () => await Throw3())
+                };
+
+                Task.WaitAll(tasks.ToArray());
+            }
+            catch (Exception ex)
+            {
+                demystifiedException = ex.Demystify();
+            }
+
+            // Assert
+            var stackTrace = demystifiedException.ToString();
+            stackTrace = ReplaceLineEndings.Replace(stackTrace, "");
+            var trace = string.Join("", stackTrace.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries)
+                // Remove items that vary between test runners
+                .Where(s =>
+                    s != "   at Task Demystify.DynamicCompilation.DoesNotPreventStackTrace()+()=>{}" &&
+                    !s.Contains("System.Threading.Tasks.Task.WaitAll")
+                )
+                .Skip(1)
+                .ToArray())
+                // Remove Full framework back arrow
+                .Replace("<---", "");
+
+            var expected = string.Join("", new[] {
+                    "   at async Task Demystify.AggregateException.Throw1()",
+                    "   at async void Demystify.AggregateException.DemystifiesAggregateExceptions()+(?)=>{}",
+                    "   --- End of inner exception stack trace ---",
+                    "   at void Demystify.AggregateException.DemystifiesAggregateExceptions()",
+                    "---> (Inner Exception #0) System.ArgumentException: Value does not fall within the expected range.",
+                    "   at async Task Demystify.AggregateException.Throw1()",
+                    "   at async void Demystify.AggregateException.DemystifiesAggregateExceptions()+(?)=>{}",
+                    "---> (Inner Exception #1) System.NullReferenceException: Object reference not set to an instance of an object.",
+                    "   at async Task Demystify.AggregateException.Throw2()",
+                    "   at async void Demystify.AggregateException.DemystifiesAggregateExceptions()+(?)=>{}",
+                    "---> (Inner Exception #2) System.InvalidOperationException: Operation is not valid due to the current state of the object.",
+                    "   at async Task Demystify.AggregateException.Throw3()",
+                    "   at async void Demystify.AggregateException.DemystifiesAggregateExceptions()+(?)=>{}"});
+
+            Assert.Equal(expected, trace);
+        }
+
+        async Task Throw1()
+        {
+            await Task.Delay(1).ConfigureAwait(false);
+            throw new ArgumentException();
+        }
+
+        async Task Throw2()
+        {
+            await Task.Delay(1).ConfigureAwait(false);
+            throw new NullReferenceException();
+        }
+
+        async Task Throw3()
+        {
+            await Task.Delay(1).ConfigureAwait(false);
+            throw new InvalidOperationException();
+        }
+
+
+        private Regex ReplaceLineEndings = new Regex(" in [^\n\r]+");
+    }
+}