freeze-thaw: added function test

tests-extra/tests/events/freeze_thaw/data/example.zone

+$ORIGIN example.
+$TTL 1200
+
+@ SOA ns admin 1 25 25 80 600
+  NS ns
+ns AAAA ::0

tests-extra/tests/events/freeze_thaw/data/example.zone.1

+$ORIGIN example.
+$TTL 1200
+
+@ SOA ns admin 2 35 35 113 600
+  NS ns
+ns AAAA ::0
+added A 1.2.3.4

tests-extra/tests/events/freeze_thaw/data/example.zone.2

+$ORIGIN example.
+$TTL 1200
+
+@ SOA ns admin 3 35 35 113 600
+  NS ns
+ns AAAA ::0
+added A 1.2.3.4
+more A 1.2.3.5

tests-extra/tests/events/freeze_thaw/test.py

+#!/usr/bin/env python3
+
+'''Test of freeze-thaw feature'''
+
+from dnstest.test import Test
+
+t = Test(tsig=False)
+
+master = t.server("knot")
+slave = t.server("knot")
+
+zone = t.zone("example.", storage=".")
+t.link(zone, master, slave)
+
+t.start()
+
+master.zone_wait(zone)
+slave.zone_wait(zone)
+
+slave.ctl("zone-freeze")
+
+master.update_zonefile(zone, version=1)
+master.reload()
+master.zone_wait(zone, serial=2, equal=True)
+t.sleep(1)
+
+# check that slave freezed transfer after obtained notify
+resp = slave.dig("added.example.", "A")
+resp.check(rcode="NXDOMAIN", nordata="1.2.3.4")
+
+slave.ctl("zone-refresh")
+
+# check that slave transfered when invoked from ctl
+slave.zone_wait(zone, serial=2, equal=True)
+resp = slave.dig("added.example.", "A")
+resp.check(rcode="NOERROR", rdata="1.2.3.4")
+
+# check that update is refused
+up = slave.update(zone)
+up.add("noddns", 3600, "A", "1.2.3.6")
+up.send("REFUSED")
+t.sleep(2)
+resp = slave.dig("noddns.example.", "A")
+resp.check(rcode="NXDOMAIN", nordata="1.2.3.6")
+
+master.update_zonefile(zone, version=2)
+master.reload()
+master.zone_wait(zone, serial=3, equal=True)
+t.sleep(1)
+
+slave.ctl("zone-thaw")
+
+# check that slave retransfered immediately after thaw
+slave.zone_wait(zone, serial=3, equal=True)
+resp = slave.dig("more.example.", "A")
+resp.check(rcode="NOERROR", rdata="1.2.3.5")
+
+# check that update works now
+up = slave.update(zone)
+up.add("ddns", 3600, "A", "1.2.3.7")
+up.send("NOERROR")
+t.sleep(2)
+resp = slave.dig("ddns.example.", "A")
+resp.check(rcode="NOERROR", rdata="1.2.3.7")
+
+t.stop()