my $res = $s->gets(13);
if( !is $res, "hello, world!", "puts() and gets() ok") {
    (my $s = $res) =~ s!([^\w])!sprintf '\\x%02x', ord($1)!ge;
    diag $s;
    ($s = "hello, world!") =~ s!([^\w])!sprintf '\\x%02x', ord($1)!ge;
    diag $s;
};