runtime/pprof: print stderr on test failure

Print Stderr on test failure to track down the intermittent
test failure reported in issue #62352.

Change-Id: I547a3220dc07d05578dac093d6c028a9103b552a
Reviewed-on: https://go-review.googlesource.com/c/go/+/524156
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/runtime/pprof/vminfo_darwin_test.go b/src/runtime/pprof/vminfo_darwin_test.go
index c476110b09f65361680680bd7ff5b62f4a98eb11..b2b025668e04b9610a1ef455592f7478a743b932 100644 (file)
--- a/src/runtime/pprof/vminfo_darwin_test.go
+++ b/src/runtime/pprof/vminfo_darwin_test.go
@@ -12,6 +12,7 @@ import (
        "internal/abi"
        "internal/testenv"
        "os"
+       "os/exec"
        "strconv"
        "strings"
        "testing"
@@ -54,9 +55,14 @@ func TestVMInfo(t *testing.T) {
 func useVMMap(t *testing.T) (hi, lo uint64) {
        pid := strconv.Itoa(os.Getpid())
        testenv.MustHaveExecPath(t, "vmmap")
-       out, err := testenv.Command(t, "vmmap", pid).Output()
+       cmd := testenv.Command(t, "vmmap", pid)
+       out, err := cmd.Output()
        if err != nil {
-               t.Fatal(err)
+               t.Logf("vmmap failed: %s", out)
+               if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
+                       t.Fatalf("%v: %v\n%s", cmd, err, ee.Stderr)
+               }
+               t.Fatalf("%v: %v", cmd, err)
        }
        return parseVmmap(t, out)
 }