my $string = "TEST\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0";
if (! -s 'a.txt') {
	open my $fh, '>', 'a.txt';
	binmode $fh;
	print $fh $string;
	close $fh;
}

open my $fh2, '<', 'a.txt';
binmode $fh2;
my $data = <$fh2>;
close $fh2;

if (length($string) != length($data)) {
	die "STRANGE!";
}