Make available the XPath path of the node where a SyntaxError occurred during Schema validation

ext/nokogiri/xml_syntax_error.c

@@ -44,6 +44,7 @@ noko__error_raise(void *ctx, xmlErrorConstPtr error)
 VALUE
 noko_xml_syntax_error__wrap(xmlErrorConstPtr error)
 {
+  xmlChar *c_path ;
   VALUE msg, e, klass;
 
   klass = cNokogiriXmlSyntaxError;
@@ -61,16 +62,21 @@ noko_xml_syntax_error__wrap(xmlErrorConstPtr error)
       );
 
   if (error) {
+    c_path = xmlGetNodePath(error->node);
+
     rb_iv_set(e, "@domain", INT2NUM(error->domain));
     rb_iv_set(e, "@code", INT2NUM(error->code));
     rb_iv_set(e, "@level", INT2NUM((short)error->level));
     rb_iv_set(e, "@file", RBSTR_OR_QNIL(error->file));
     rb_iv_set(e, "@line", INT2NUM(error->line));
+    rb_iv_set(e, "@path", RBSTR_OR_QNIL(c_path));
     rb_iv_set(e, "@str1", RBSTR_OR_QNIL(error->str1));
     rb_iv_set(e, "@str2", RBSTR_OR_QNIL(error->str2));
     rb_iv_set(e, "@str3", RBSTR_OR_QNIL(error->str3));
     rb_iv_set(e, "@int1", INT2NUM(error->int1));
     rb_iv_set(e, "@column", INT2NUM(error->int2));
+
+    xmlFree(c_path);
   }
 
   return e;

lib/nokogiri/xml/syntax_error.rb

@@ -24,6 +24,15 @@ def aggregate(errors)
       attr_reader :level
       attr_reader :file
       attr_reader :line
+
+      # The XPath path of the node that caused the error when validating a `Nokogiri::XML::Document`.
+      #
+      # This attribute will only be non-nil when the error is emitted by `Schema#validate` on
+      # Document objects. It will return `nil` for DOM parsing errors and for errors emitted during
+      # Schema validation of files.
+      #
+      # ⚠ `#path` is not supported on JRuby, where it will always return `nil`.
+      attr_reader :path
       attr_reader :str1
       attr_reader :str2
       attr_reader :str3

test/html4/test_document.rb

@@ -813,6 +813,7 @@ def test_silencing_nonparse_errors_during_attribute_insertion_1262
                   Nokogiri::HTML4.parse(input, nil, nil, parse_options)
                 end
                 assert_match(/Parser without recover option encountered error or warning/, exception.to_s)
+                assert_nil(exception.path)
               end
             end
 
@@ -835,6 +836,7 @@ def test_silencing_nonparse_errors_during_attribute_insertion_1262
                   Nokogiri::HTML4.parse(input, nil, "UTF-8", parse_options)
                 end
                 assert_match(/Parser without recover option encountered error or warning/, exception.to_s)
+                assert_nil(exception.path)
               end
             end
 

test/xml/test_document.rb

@@ -1087,9 +1087,10 @@ def test_can_be_closed
               let(:parse_options) { xml_strict }
 
               it "raises exception on parse error" do
-                assert_raises Nokogiri::SyntaxError do
+                error = assert_raises Nokogiri::SyntaxError do
                   Nokogiri::XML.parse(input, nil, nil, parse_options)
                 end
+                assert_nil(error.path)
               end
             end
 

test/xml/test_schema.rb

@@ -159,6 +159,17 @@ class TestNokogiriXMLSchema < Nokogiri::TestCase
 
         assert(errors = xsd.validate(doc))
         assert_equal(2, errors.length)
+        if Nokogiri.uses_libxml?
+          assert_equal(
+            ["/purchaseOrder/billTo/state", "/purchaseOrder/shipTo/state"],
+            errors.map(&:path).sort,
+          )
+        else
+          assert_equal(
+            [nil, nil],
+            errors.map(&:path).sort,
+          )
+        end
       end
 
       it "validate_invalid_file" do
@@ -171,6 +182,10 @@ class TestNokogiriXMLSchema < Nokogiri::TestCase
 
         assert(errors = xsd.validate(tempfile.path))
         assert_equal(2, errors.length)
+        assert_equal(
+          [nil, nil],
+          errors.map(&:path).sort,
+        )
       end
 
       it "validate_non_document" do

test/xml/test_syntax_error.rb

@@ -58,5 +58,6 @@
       assert_nil error.column
       assert_nil error.level
     end
+    assert_nil error.path
   end
 end