From 42307e821d33eeba2cecc08127f402db0aa66a8c Mon Sep 17 00:00:00 2001
From: Brad Wilson <dotnetguy@gmail.com>
Date: Sun, 24 Jul 2022 17:28:08 -0700
Subject: [PATCH] Fixes #2556: Xunit.Sdk.MultipleException Empty

---
 src/common/ExceptionUtility.cs | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/common/ExceptionUtility.cs b/src/common/ExceptionUtility.cs
index df3f03ead..a602127b1 100644
--- a/src/common/ExceptionUtility.cs
+++ b/src/common/ExceptionUtility.cs
@@ -1,5 +1,8 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
 using Xunit.Abstractions;
 
 #if XUNIT_FRAMEWORK
@@ -33,6 +36,23 @@ public static string CombineStackTraces(IFailureInformation failureInfo)
             return GetStackTrace(failureInfo, 0);
         }
 
+#if XUNIT_FRAMEWORK
+        static readonly ConcurrentDictionary<Type, PropertyInfo> innerExceptionsPropertyByType = new();
+
+        static IEnumerable<Exception> GetInnerExceptions(Exception ex)
+        {
+            if (ex is AggregateException aggEx)
+                return aggEx.InnerExceptions;
+
+            var prop = innerExceptionsPropertyByType.GetOrAdd(
+                ex.GetType(),
+                t => t.GetRuntimeProperties().FirstOrDefault(p => p.Name == "InnerExceptions" && p.CanRead)
+            );
+
+            return prop?.GetValue(ex) as IEnumerable<Exception>;
+        }
+#endif
+
         static bool ExcludeStackFrame(string stackFrame)
         {
             Guard.ArgumentNotNull("stackFrame", stackFrame);
@@ -176,9 +196,9 @@ static void ConvertExceptionToFailureInformation(Exception ex, int parentIndex,
             indices.Add(parentIndex);
 
 #if XUNIT_FRAMEWORK
-            var aggEx = ex as AggregateException;
-            if (aggEx != null)
-                foreach (var innerException in aggEx.InnerExceptions)
+            var innerExceptions = GetInnerExceptions(ex);
+            if (innerExceptions != null)
+                foreach (var innerException in innerExceptions)
                     ConvertExceptionToFailureInformation(innerException, myIndex, exceptionTypes, messages, stackTraces, indices);
             else
 #endif
@@ -193,6 +213,5 @@ class FailureInformation : IFailureInformation
             public string[] StackTraces { get; set; }
             public int[] ExceptionParentIndices { get; set; }
         }
-
     }
 }