cmd := testenv.Command(t, testenv.GoToolPath(t), args...)
	cmd.Dir = dir
	if *dryrun {
		fmt.Printf("%s\n", asCommandLine("", cmd))
		return ""
	}
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		t.Fatalf("error running cmd (%s): %v\nstdout:\n%sstderr:\n%s\n", asCommandLine("", cmd), err, stdout.String(), stderr.String())
	}

	if s := stderr.String(); s != "" {

	if testing.Verbose() {
		fmt.Printf("About to run %s\n", asCommandLine("", cmd))
	}

	var stdout, stderr strings.Builder
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		t.Fatalf("error running cmd %s: %v\nstdout:\n%sstderr:\n%s\n", asCommandLine("", cmd), err, stdout.String(), stderr.String())
	}

	if s := stderr.String(); s != "" {

	if s == "" || strings.ContainsAny(s, "\\ ;#*&$~?!|[]()<>{}`") {
		s = "'" + s + "'"
	}
	return s
}

// asCommandLine renders cmd as something that could be copy-and-pasted into a command line
func asCommandLine(cwd string, cmd *exec.Cmd) string {
	s := "("
	if cmd.Dir != "" && cmd.Dir != cwd {
		s += "cd" + escape(cmd.Dir) + ";"
	}
	for _, e := range cmd.Env {

    public static <T> List<T> nonEmptyOrNull(Iterable<T> iterable) {
        ImmutableList<T> list = ImmutableList.copyOf(iterable);
        return list.isEmpty() ? null : list;
    }

    public static String asCommandLine(Iterable<String> arguments) {
        return Joiner.on(" ").join(collect(arguments, InternalTransformers.asSafeCommandLineArgument()));
    }

        logDeprecation(7);
        ImmutableList<T> list = ImmutableList.copyOf(iterable);
        return list.isEmpty() ? null : list;
    }

    public static String asCommandLine(Iterable<String> arguments) {
        logDeprecation(7);
        return Joiner.on(" ").join(collect(arguments, Transformers.asSafeCommandLineArgument()));
    }