t.Fatalf("failed to start tracing: %v", err)
	}
	if err := Start(buf); err == nil {
		t.Fatalf("succeed to start tracing second time")
	}
	Stop()
	Stop()
}

func saveTrace(t *testing.T, buf *bytes.Buffer, name string) {
	if !*saveTraces {
		return
	}
	if err := os.WriteFile(name+".trace", buf.Bytes(), 0600); err != nil {
		t.Errorf("failed to write trace file: %s", err)
	}

	if testing.Short() {
		t.Skip("skipping due to -short")
	}
	// Note the HasCGO() test below; this is to prevent the test
	// running if CGO_ENABLED=0 is in effect.
	haverace := platform.RaceDetectorSupported(runtime.GOOS, runtime.GOARCH)
	if haverace && testenv.HasCGO() {
		bmodes = append(bmodes, "-race")
	}
	for _, bmode := range bmodes {
		scenarios := []struct {
			mode     string
			expected string
			musthave []string