tests-extra: Duplicate RDATA differing only in case

tests-extra/data/records.zone

@@ -114,7 +114,6 @@ dUpL		MX	10 sOMe.doMAin
 bad-order	NS      B.foo.
 bad-order	NS      a.foo.
 
-
 ; CNAME loop
 *.loop1 CNAME a.loop2
 *.loop2 CNAME a.loop1

tests-extra/tests/records/duplicates/data/duplicates.zone

+$ORIGIN duplicates.
+$TTL 3600
+
+@	SOA	dns1 hostmaster 2010111213 10800 3600 1209600 7200
+	NS	dns1
+
+dns1	A	192.0.2.1
+	AAAA	2001:DB8::1
+
+; Duplicate RDATA differing only in case
+dupl            MX      10 some.domain.
+dupl            MX      10 Some.Domain.
+DuPl            MX      10 some.domain.
+dUpL            MX      10 sOMe.doMAin.
+

tests-extra/tests/records/duplicates/test.py

+#!/usr/bin/env python3
+
+''' Test for loading records with RDATA and owners differing only in case '''
+
+from dnstest.utils import *
+from dnstest.test import Test
+
+t = Test()
+
+knot = t.server("knot")
+zone = t.zone("duplicates.", storage=".")
+t.link(zone, knot)
+
+t.start()
+
+knot.zones_wait(zone)
+
+# Request AXFR from both Knot
+resp = knot.dig("duplicates.", "AXFR")
+
+# If Knot has not properly handled the case, there will be some redundant record
+count = 0
+for msg in resp.resp:
+	count += len(msg.answer)
+
+compare(count, 6, "AXFR record count")
+	
+t.end()