The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.
OALDERS / HTML-Restrict-2.2.1 / t / declaration.t 
#!/usr/bin/env perl

use warnings;
use strict;

use HTML::Restrict;
use Test::More;

my $hr = HTML::Restrict->new;

my $text  = '<!DOCTYPE HTML> ';
$hr->debug( 1 );

is $hr->process( $text ), '', 'declaration not preserved';
$hr->allow_declaration( 1 );
is $hr->process( $text ), '<!DOCTYPE HTML>', 'declaration is preserved';

$text = '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">';
is $hr->process( $text ), $text, 'declaration preserved';

done_testing();