From 63baea9922c48954b9286ab99470fae94f4a4d08 Mon Sep 17 00:00:00 2001
From: Brian Robbins <brianrob@microsoft.com>
Date: Sat, 21 Feb 2026 20:21:36 -0800
Subject: [PATCH] Fix Debug.Assert failures exposed by ThrowingTraceListener in
 SpeedScope tests

Two issues caused Debug.Assert failures when ThrowingTraceListener was active:

1. DynamicTraceEventParser.EnumerateTemplates produced duplicate templates when
   both registeredParser and eventPipeTraceEventParser knew about the same event,
   causing Subscribe to assert on the duplicate with mayHaveExistedBefore=false.
   Fix: filter eventPipeTraceEventParser templates against registeredParser.

2. ApplicationServerTraceEventParser is auto-generated and has many events sharing
   the same task name, producing duplicate computed event names that
   ConfirmAllEventsAreInEnumeration cannot handle.
   Fix: skip this parser from the validation.

Also remove the listener-clearing hack in SpeedScope tests since the underlying
asserts are now fixed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../DebugAssertionTests.cs                       |  3 +++
 .../ThrowingTraceListener.cs                     | 12 +++++++++++-
 src/TraceEvent/DynamicTraceEventParser.cs        | 12 ++++++++++--
 .../Speedscope/SpeedScopeExporterTests.cs        | 16 ----------------
 src/TraceEvent/TraceEvent.cs                     |  7 ++++++-
 5 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/src/PerfView.TestUtilities/DebugAssertionTests.cs b/src/PerfView.TestUtilities/DebugAssertionTests.cs
index c561d9f4b..710abc8e7 100644
--- a/src/PerfView.TestUtilities/DebugAssertionTests.cs
+++ b/src/PerfView.TestUtilities/DebugAssertionTests.cs
@@ -11,6 +11,9 @@
     /// <remarks>
     /// <para>This file can be linked into any project which needs to validate that assertions are behaving correctly
     /// for the purpose of unit testing.</para>
+    /// <para>On .NET Framework, assertion failures throw via <see cref="ThrowingTraceListener"/> registered in
+    /// app.config. On .NET 5+, the DefaultTraceListener already throws on assertion failures, so no
+    /// additional listener configuration is needed.</para>
     /// </remarks>
     public class DebugAssertionTests
     {
diff --git a/src/PerfView.TestUtilities/ThrowingTraceListener.cs b/src/PerfView.TestUtilities/ThrowingTraceListener.cs
index b57b69fed..52eb976ee 100644
--- a/src/PerfView.TestUtilities/ThrowingTraceListener.cs
+++ b/src/PerfView.TestUtilities/ThrowingTraceListener.cs
@@ -5,7 +5,10 @@
 
 namespace PerfView.TestUtilities
 {
-    // To enable this for a process, add the following to the app.config for the project:
+    // This listener converts Debug.Assert/Trace.Assert failures into xUnit test failures
+    // by throwing from the Fail() method.
+    //
+    // On .NET Framework (net462), this must be registered via app.config <system.diagnostics>:
     //
     // <configuration>
     //  <system.diagnostics>
@@ -17,6 +20,13 @@ namespace PerfView.TestUtilities
     //    </trace>
     //  </system.diagnostics>
     //</configuration>
+    //
+    // On .NET 5+, the app.config <system.diagnostics> section is NOT
+    // processed, so this listener is never registered. However, the DefaultTraceListener
+    // on .NET 5+ already throws on assert failures, so no additional configuration is
+    // needed — Debug.Assert and Trace.Assert will throw without this listener.
+    // Should this behavior change, the ThrowingTraceListener tests will fail, which will tell us we
+    // need to do something to re-enable this listener.
     public sealed class ThrowingTraceListener : TraceListener
     {
         public override void Fail(string message, string detailMessage)
diff --git a/src/TraceEvent/DynamicTraceEventParser.cs b/src/TraceEvent/DynamicTraceEventParser.cs
index 34a60e7a7..7415c4637 100644
--- a/src/TraceEvent/DynamicTraceEventParser.cs
+++ b/src/TraceEvent/DynamicTraceEventParser.cs
@@ -279,8 +279,16 @@ protected internal override void EnumerateTemplates(Func<string, string, EventFi
             // also enumerate any events from the registeredParser.  
             registeredParser.EnumerateTemplates(eventsToObserve, callback);
 
-            // also enumerate any events from the eventPipeTraceEventParser
-            eventPipeTraceEventParser.EnumerateTemplates(eventsToObserve, callback);
+            // also enumerate any events from the eventPipeTraceEventParser.
+            // Filter out any duplicates that the registeredParser already knows about,
+            // similar to how manifest-based templates are filtered above.
+            eventPipeTraceEventParser.EnumerateTemplates(eventsToObserve, delegate (TraceEvent template)
+            {
+                if (!registeredParser.HasDefinitionForTemplate(template))
+                {
+                    callback(template);
+                }
+            });
         }
 
         private class PartialManifestInfo
diff --git a/src/TraceEvent/TraceEvent.Tests/Speedscope/SpeedScopeExporterTests.cs b/src/TraceEvent/TraceEvent.Tests/Speedscope/SpeedScopeExporterTests.cs
index 3402f08bd..fbe9d7643 100644
--- a/src/TraceEvent/TraceEvent.Tests/Speedscope/SpeedScopeExporterTests.cs
+++ b/src/TraceEvent/TraceEvent.Tests/Speedscope/SpeedScopeExporterTests.cs
@@ -4,7 +4,6 @@
 using Microsoft.Diagnostics.Tracing.Stacks;
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.IO;
 using System.IO.Compression;
 using System.Linq;
@@ -12,13 +11,6 @@
 
 using static Microsoft.Diagnostics.Tracing.Stacks.StackSourceWriterHelper;
 
-// For Debug.Listeners
-#if NETCOREAPP3_0_OR_GREATER
-using Trace = System.Diagnostics.Trace;
-#else
-using Trace = System.Diagnostics.Debug;
-#endif
-
 namespace TraceEventTests
 {
     public class SpeedScopeStackSourceWriterTests
@@ -343,10 +335,6 @@ public void ValidationAllowsForCompleteResults()
         [InlineData("only_managed_samples.nettrace.zip")]
         public void CanConvertProvidedTraceFiles(string zippedTraceFileName)
         {
-            var debugListenersCopy = new TraceListener[Trace.Listeners.Count];
-            Trace.Listeners.CopyTo(debugListenersCopy, index: 0);
-            Trace.Listeners.Clear();
-
             string fileToUnzip = Path.Combine("inputs", "speedscope", zippedTraceFileName);
             string unzippedFile = Path.ChangeExtension(fileToUnzip, string.Empty);
 
@@ -402,10 +390,6 @@ public void CanConvertProvidedTraceFiles(string zippedTraceFileName)
                 {
                     File.Delete(unzippedFile);
                 }
-                if (debugListenersCopy.Length > 0)
-                {
-                    Trace.Listeners.AddRange(debugListenersCopy);
-                }
             }
         }
 
diff --git a/src/TraceEvent/TraceEvent.cs b/src/TraceEvent/TraceEvent.cs
index e6045231b..921f3747c 100644
--- a/src/TraceEvent/TraceEvent.cs
+++ b/src/TraceEvent/TraceEvent.cs
@@ -2882,7 +2882,12 @@ protected TraceEventParser(TraceEventSource source, bool dontRegister = false)
             }
 
 #if DEBUG
-            if (GetProviderName() != null && !m_ConfirmedAllEventsAreInEnumeration && !(this is PredefinedDynamicTraceEventParser))
+            // ApplicationServerTraceEventParser is auto-generated and has many events sharing the same
+            // task name, producing duplicate computed event names that ConfirmAllEventsAreInEnumeration
+            // cannot handle.
+            if (GetProviderName() != null && !m_ConfirmedAllEventsAreInEnumeration &&
+                !(this is PredefinedDynamicTraceEventParser) &&
+                !(this is Parsers.ApplicationServerTraceEventParser))
             {
                 ConfirmAllEventsAreInEnumeration();
                 m_ConfirmedAllEventsAreInEnumeration = true;