fix: include line numbers in HTML parser error messages (GH #233)

lib/XML/LibXML/Error.pm

@@ -221,6 +221,8 @@ sub as_string {
              and
              $self->{line})  {
         $where="Entity: line $self->{line}";
+    } elsif ($self->{line}) {
+        $where="line $self->{line}";
     }
     if ($self->{nodename}) {
         $where.=": element ".$self->{nodename};

t/46err_html_line.t

@@ -0,0 +1,89 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+# GH #233: HTML parser errors should include line numbers in as_string output
+# https://github.com/cpan-authors/XML-LibXML/issues/233
+
+use Test::More;
+
+if (! XML::LibXML::HAVE_STRUCT_ERRORS()) {
+    plan skip_all => 'XML::LibXML does not have structured errors';
+}
+else {
+    plan tests => 6;
+}
+
+use XML::LibXML;
+use XML::LibXML::Error;
+
+my $p = XML::LibXML->new();
+
+my $html = "<html>\n<body>\n<p>text\n</p>\n<div><b>bad</i></div>\n</body>\n</html>";
+
+my @warnings;
+{
+    local $SIG{__WARN__} = sub { push @warnings, $_[0] };
+    eval { $p->parse_html_string($html, { recover => 1 }) };
+}
+
+SKIP:
+{
+    if (! @warnings) {
+        skip('No warnings captured from HTML parse - possibly old libxml2', 6);
+    }
+
+    my $err = $warnings[0];
+
+    skip('Warning is not an XML::LibXML::Error object', 6)
+        if (! ref($err) or ! $err->isa('XML::LibXML::Error'));
+
+    # Walk the chain to find the innermost (first) error
+    my $first = $err;
+    while ($first->_prev && ref($first->_prev)) {
+        $first = $first->_prev;
+    }
+
+    # TEST
+    is($first->{domain}, XML::LibXML::Error::XML_ERR_FROM_HTML(),
+        'Error domain is HTML parser');
+
+    # TEST
+    ok(defined $first->line(), 'HTML error has a line number');
+
+    # TEST
+    ok($first->line() > 0, 'HTML error line number is positive');
+
+    my $str = $first->as_string();
+
+    # TEST
+    like($str, qr/line \d+/, 'as_string includes line number for HTML errors');
+
+    # TEST
+    like($str, qr/HTML parser/, 'as_string identifies HTML parser domain');
+
+    # XML parser errors preserve existing "Entity: line N" format
+    my @xml_warns;
+    {
+        local $SIG{__WARN__} = sub { push @xml_warns, $_[0] };
+        eval { $p->parse_string("<root>\n<x>\n</y>\n</root>", { recover => 1 }) };
+    }
+
+    my $xml_err;
+    if (@xml_warns && ref($xml_warns[0]) && $xml_warns[0]->isa('XML::LibXML::Error')) {
+        $xml_err = $xml_warns[0];
+        while ($xml_err->_prev && ref($xml_err->_prev)) {
+            $xml_err = $xml_err->_prev;
+        }
+    }
+
+    SKIP:
+    {
+        skip('No XML warnings to compare', 1) if (! $xml_err);
+
+        my $xml_str = $xml_err->as_string();
+        # TEST
+        like($xml_str, qr/:\d+:/, 'XML parser error retains file:line format');
+    }
+}