parseGroup: stop misattributing body fields after nested groups

Author: agmt

message.go

@@ -310,6 +310,7 @@ func parseGroup(mp *msgParser, tags []Tag) {
 	dm := mp.msg.fields[mp.fieldIndex : mp.fieldIndex+1]
 	fields := getGroupFields(mp.msg, tags, mp.appDataDictionary)
 
+parseLoop:
 	for {
 		mp.fieldIndex++
 		mp.parsedFieldBytes = &mp.msg.fields[mp.fieldIndex]
@@ -350,16 +351,15 @@ func parseGroup(mp *msgParser, tags []Tag) {
 				fields = getGroupFields(mp.msg, searchTags, mp.appDataDictionary)
 				continue
 			}
-			if len(tags) > 1 {
-				searchTags = tags[:len(tags)-1]
-			}
-			// Did this tag occur after a nested group and belongs to the parent group.
-			if isNumInGroupField(mp.msg, searchTags, mp.appDataDictionary) {
-				// Add the field member to the group.
-				dm = append(dm, *mp.parsedFieldBytes)
-				// Continue parsing the parent group.
-				fields = getGroupFields(mp.msg, searchTags, mp.appDataDictionary)
-				continue
+			// The tag isn't a member of the current group. Walk up: if an
+			// ancestor group includes it, resume there; otherwise it's body-level.
+			for len(tags) > 1 {
+				tags = tags[:len(tags)-1]
+				fields = getGroupFields(mp.msg, tags, mp.appDataDictionary)
+				if isGroupMember(mp.parsedFieldBytes.tag, fields) {
+					dm = append(dm, *mp.parsedFieldBytes)
+					continue parseLoop
+				}
 			}
 			// Add the repeating group.
 			mp.msg.Body.add(dm)

message_test.go

@@ -143,16 +143,13 @@ func (s *MessageSuite) TestParseGroup_BodyFieldAfterNestedGroup() {
 	// NoQuoteSets count (group delimiter) lands in Body as expected.
 	s.True(s.msg.Body.Has(Tag(296)))
 
-	// ToDo: should be correct — QuoteStatus (297) must be a top-level body
-	// field per FIX 4.4. Current parseGroup logic silently absorbs 297 into
-	// the NoQuoteSets group buffer because it only checks whether the
-	// parent tag is a NumInGroup, not whether 297 is a member of the
-	// parent group template.
-	s.False(s.msg.Body.Has(Tag(297)),
-		"BUG: QuoteStatus (297) is absent from Body.FieldMap — parser "+
-			"mis-attributed it to the parent NoQuoteSets group. This "+
-			"assertion documents the bug; flip to s.True(...) when "+
-			"parseGroup is fixed.")
+	// QuoteStatus (297) must be a top-level body field per FIX 4.4.
+	s.True(s.msg.Body.Has(Tag(297)),
+		"QuoteStatus (297) must land at the body level; it is a body field "+
+			"in MassQuoteAcknowledgement, not a member of NoQuoteSets.")
+	val, verr := s.msg.Body.GetInt(Tag(297))
+	s.Nil(verr)
+	s.Equal(1, val)
 }
 
 func (s *MessageSuite) TestBuild() {