Add unit tests and release note for dns_publish_fixed_ip

Follow-up to https://review.opendev.org/#/c/679834/ which
added the options and lacked both a release note and
minimal option-handling unit tests.

Change-Id: Ibb2820add9b2fedaf5a8b1a77babf043f6641724
Signed-off-by: Dean Troyer <dtroyer@gmail.com>

openstackclient/tests/unit/network/v2/test_subnet.py

@@ -460,6 +460,44 @@ class TestCreateSubnet(TestSubnet):
         self.assertEqual(self.columns, columns)
         self.assertItemEqual(self.data, data)
 
+    def _test_create_with_dns(self, publish_dns=True):
+        arglist = [
+            "--subnet-range", self._subnet.cidr,
+            "--network", self._subnet.network_id,
+            self._subnet.name,
+        ]
+        if publish_dns:
+            arglist += ['--dns-publish-fixed-ip']
+        else:
+            arglist += ['--no-dns-publish-fixed-ip']
+        verifylist = [
+            ('name', self._subnet.name),
+            ('subnet_range', self._subnet.cidr),
+            ('network', self._subnet.network_id),
+            ('ip_version', self._subnet.ip_version),
+            ('gateway', 'auto'),
+        ]
+        verifylist.append(('dns_publish_fixed_ip', publish_dns))
+
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+        columns, data = (self.cmd.take_action(parsed_args))
+
+        self.network.create_subnet.assert_called_once_with(
+            cidr=self._subnet.cidr,
+            ip_version=self._subnet.ip_version,
+            name=self._subnet.name,
+            network_id=self._subnet.network_id,
+            dns_publish_fixed_ip=publish_dns,
+        )
+        self.assertEqual(self.columns, columns)
+        self.assertItemEqual(self.data, data)
+
+    def test_create_with_dns(self):
+        self._test_create_with_dns(publish_dns=True)
+
+    def test_create_with_no_dns(self):
+        self._test_create_with_dns(publish_dns=False)
+
     def _test_create_with_tag(self, add_tags=True):
         arglist = [
             "--subnet-range", self._subnet.cidr,

releasenotes/notes/bug-1784879-9b632174d4af853f.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Add ``--dns-publish-fixed-ip`` and ``--no-dns-publish-fixed-ip``
+    options to ``create subnet`` and ``set subnet`` commands to
+    control the publishing of fixed IPs in DNS when the
+    ``subnet_dns_publish_fixed_ip`` Neutron extension is enabled.
+    [Bug `1784879 <https://bugs.launchpad.net/neutron/+bug/1784879>`_]