Check for duplicate tag IDs

[petdance]

It is not allowed to have duplicate IDs in your HTML. Check for this.

[petdance]

sub html_lacks_duplicate_ids {
    my $self = shift;
    my $msg = shift // 'list of duplicate ids should be empty: ';

    my @dupes;

    if ( $self->content() ) {
        if ( my @ids = $self->content =~ /id="([^"]+)/g ) {
            my %seen;
            foreach my $id ( @ids ) {
                if ( exists $seen{$id} ) {
                    push @dupes, $id;
                }
                ++$seen{ $id };
            }
        }
    }

    $msg .= join(', ', @dupes) if @dupes;
    my $ok = ok( !@dupes, $msg );
    return $ok;
}

[petdance]

Note: That is NOT how we want to implement. It's just @moregan's scratch implementation.

[kryde]

cf my ticket #20
though maybe the patch I submitted there will have bit rotted in the interim ...