Add ip version filter to subnet list

This patch will add argument ip-version to command
subnet list

Change-Id: If7458d4979e53aec7e2633c4f1779c3810f9a3f1
Closes-Bug: #1581179

doc/source/command-objects/subnet.rst

@@ -147,6 +147,10 @@ List subnets
 
     List additional fields in output
 
+.. option:: --ip-version {4, 6}
+
+    List only subnets of given IP version in output
+
 subnet set
 ----------
 

openstackclient/network/v2/subnet.py

@@ -296,10 +296,22 @@ class ListSubnet(command.Lister):
             default=False,
             help=_("List additional fields in output")
         )
+        parser.add_argument(
+            '--ip-version',
+            type=int,
+            choices=[4, 6],
+            metavar='<ip-version>',
+            dest='ip_version',
+            help=_("List only subnets of given IP version in output"
+                   "Allowed values for IP version are 4 and 6."),
+        )
         return parser
 
     def take_action(self, parsed_args):
-        data = self.app.client_manager.network.subnets()
+        filters = {}
+        if parsed_args.ip_version:
+            filters['ip_version'] = parsed_args.ip_version
+        data = self.app.client_manager.network.subnets(**filters)
 
         headers = ('ID', 'Name', 'Network', 'Subnet')
         columns = ('id', 'name', 'network_id', 'cidr')

openstackclient/tests/network/v2/test_subnet.py

@@ -469,6 +469,22 @@ class TestListSubnet(TestSubnet):
         self.assertEqual(self.columns_long, columns)
         self.assertEqual(self.data_long, list(data))
 
+    def test_subnet_list_ip_version(self):
+        arglist = [
+            '--ip-version', str(4),
+        ]
+        verifylist = [
+            ('ip_version', 4),
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+
+        columns, data = self.cmd.take_action(parsed_args)
+        filters = {'ip_version': 4}
+
+        self.network.subnets.assert_called_once_with(**filters)
+        self.assertEqual(self.columns, columns)
+        self.assertEqual(self.data, list(data))
+
 
 class TestSetSubnet(TestSubnet):
 

releasenotes/notes/bug-1581179-4d15dc504777f9e7.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  -
+    Add the ``--ip-version`` option to the ``subnet list`` command. This
+    will output subnets based on IP version filter.
+    [`Bug 1581179 <https://bugs.launchpad.net/python-openstackclient/+bug/1581179>`_]