runtime/pprof: TestVMInfo reworked to avoid test flakiness.

Fixes #62352.

Change-Id: Ib137a5f39d4630c4737badfabe8e6740593ecbcf
Reviewed-on: https://go-review.googlesource.com/c/go/+/527276
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>

diff --git a/src/runtime/pprof/vminfo_darwin_test.go b/src/runtime/pprof/vminfo_darwin_test.go
index b2b025668e04b9610a1ef455592f7478a743b932..1a3b67a0bf1e3dc3475f093addf4381cc7cd34c8 100644 (file)
--- a/src/runtime/pprof/vminfo_darwin_test.go
+++ b/src/runtime/pprof/vminfo_darwin_test.go
@@ -9,6 +9,7 @@ package pprof
 import (
        "bufio"
        "bytes"
+       "fmt"
        "internal/abi"
        "internal/testenv"
        "os"
@@ -56,19 +57,30 @@ func useVMMap(t *testing.T) (hi, lo uint64) {
        pid := strconv.Itoa(os.Getpid())
        testenv.MustHaveExecPath(t, "vmmap")
        cmd := testenv.Command(t, "vmmap", pid)
-       out, err := cmd.Output()
+       out, cmdErr := cmd.Output()
+       if cmdErr != nil {
+               t.Logf("vmmap output: %s", out)
+               if ee, ok := cmdErr.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
+                       t.Logf("%v: %v\n%s", cmd, cmdErr, ee.Stderr)
+               }
+               t.Logf("%v: %v", cmd, cmdErr)
+       }
+       // Always parse the output of vmmap since it may return an error
+       // code even if it successfully reports the text segment information
+       // required for this test.
+       hi, lo, err := parseVmmap(out)
        if err != nil {
-               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)
+               if cmdErr != nil {
+                       t.Fatalf("failed to parse vmmap output, vmmap reported an error: %v", err)
                }
-               t.Fatalf("%v: %v", cmd, err)
+               t.Logf("vmmap output: %s", out)
+               t.Fatalf("failed to parse vmmap output, vmmap did not report an error: %v", err)
        }
-       return parseVmmap(t, out)
+       return hi, lo
 }
 
 // parseVmmap parses the output of vmmap and calls addMapping for the first r-x TEXT segment in the output.
-func parseVmmap(t *testing.T, data []byte) (hi, lo uint64) {
+func parseVmmap(data []byte) (hi, lo uint64, err error) {
        // vmmap 53799
        // Process:         gopls [53799]
        // Path:            /Users/USER/*/gopls
@@ -119,13 +131,12 @@ func parseVmmap(t *testing.T, data []byte) (hi, lo uint64) {
                                locs := strings.Split(p[1], "-")
                                start, _ := strconv.ParseUint(locs[0], 16, 64)
                                end, _ := strconv.ParseUint(locs[1], 16, 64)
-                               return start, end
+                               return start, end, nil
                        }
                }
                if strings.HasPrefix(l, banner) {
                        grabbing = true
                }
        }
-       t.Fatal("vmmap no text segment found")
-       return 0, 0
+       return 0, 0, fmt.Errorf("vmmap no text segment found")
 }