From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 11 Dec 2025 18:02:36 +0000 (+0000)
Subject: runtime/trace: fix broken TestSubscribers
X-Git-Tag: go1.26rc1~1^2~17
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=89614ad264803558cfa36d460d431f7cbd4bae47;p=gostls13.git

runtime/trace: fix broken TestSubscribers

Currently we don't break out of the loop on a failure. This is
leading to timeouts trying to parse a broken trace over and over,
forever.

But there's another issue where when we try to dump the trace, we pass
only the unread portion of the bytes.Buffer.

Change-Id: I1a338eea08eaf7f592fb7dd2a736a6fe0728c62d
Reviewed-on: https://go-review.googlesource.com/c/go/+/729320
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/runtime/trace/subscribe_test.go b/src/runtime/trace/subscribe_test.go
index 6378c3401a..869ab0e75b 100644
--- a/src/runtime/trace/subscribe_test.go
+++ b/src/runtime/trace/subscribe_test.go
@@ -16,15 +16,15 @@ import (
 )
 
 func TestSubscribers(t *testing.T) {
-	validate := func(t *testing.T, source string, tr *bytes.Buffer) {
+	validate := func(t *testing.T, source string, tr []byte) {
 		defer func() {
 			if t.Failed() {
-				testtrace.Dump(t, "trace", tr.Bytes(), *dumpTraces)
+				testtrace.Dump(t, "trace", tr, *dumpTraces)
 			}
 		}()
 
 		// Prepare to read the trace snapshot.
-		r, err := inttrace.NewReader(tr)
+		r, err := inttrace.NewReader(bytes.NewReader(tr))
 		if err != nil {
 			t.Errorf("unexpected error creating trace reader for %s: %v", source, err)
 			return
@@ -45,9 +45,11 @@ func TestSubscribers(t *testing.T) {
 			}
 			if err != nil {
 				t.Errorf("unexpected error reading trace for %s: %v", source, err)
+				break
 			}
 			if err := v.Event(ev); err != nil {
 				t.Errorf("event validation failed: %s", err)
+				break
 			}
 			if ev.Kind() == inttrace.EventSync {
 				syncs = append(syncs, evs)
@@ -64,8 +66,8 @@ func TestSubscribers(t *testing.T) {
 	}
 
 	validateTraces := func(t *testing.T, trace, frTrace *bytes.Buffer) {
-		validate(t, "tracer", trace)
-		validate(t, "flightRecorder", frTrace)
+		validate(t, "tracer", trace.Bytes())
+		validate(t, "flightRecorder", frTrace.Bytes())
 	}
 	startFlightRecorder := func(t *testing.T) *trace.FlightRecorder {
 		fr := trace.NewFlightRecorder(trace.FlightRecorderConfig{})