func EscapeArg(s string) string {
	if len(s) == 0 {
		return `""`
	}
	for i := 0; i < len(s); i++ {
		switch s[i] {
		case '"', '\\', ' ', '\t':
			// Some escaping required.
			b := make([]byte, 0, len(s)+2)
			b = appendEscapeArg(b, s)
			return string(b)
		}
	}
	return s
}

// appendEscapeArg escapes the string s, as per escapeArg,

	for _, cmd := range cmds {
		compareCommandLineToArgvWithSyscall(t, "test"+cmd)
		compareCommandLineToArgvWithSyscall(t, `"cmd line"`+cmd)
		compareCommandLineToArgvWithSyscall(t, exe+cmd)

		// test both syscall.EscapeArg and os.commandLineToArgv
		args := os.CommandLineToArgv(exe + cmd)
		out, err := testenv.Command(t, args[0], args[1:]...).CombinedOutput()
		if err != nil {
			t.Fatalf("running %q failed: %v\n%v", args, err, string(out))