Rewrite the ttl system test to pytest

bin/tests/system/ttl/tests_cache_ttl.py

@@ -0,0 +1,32 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+import pytest
+
+pytest.importorskip("dns")
+import dns.message
+import dns.query
+
+
+@pytest.mark.parametrize(
+    "qname,rdtype,expected_ttl",
+    [
+        ("min-example.", "SOA", 60),
+        ("min-example.", "MX", 30),
+        ("max-example.", "SOA", 120),
+        ("max-example.", "MX", 60),
+    ],
+)
+def test_cache_ttl(qname, rdtype, expected_ttl, named_port):
+    msg = dns.message.make_query(qname, rdtype)
+    response = dns.query.udp(msg, "10.53.0.2", timeout=10, port=named_port)
+    for rr in response.answer + response.authority:
+        assert rr.ttl == expected_ttl