Add support for clearing router gateway

This patch adds the support to clear the gateway information
from a router.

Change-Id: I446c556750f080a6fc21fea8f531fd71838d648a
Implements: blueprint neutron-client-advanced-router
Partially-Implements: blueprint network-commands-options

doc/source/command-objects/router.rst

@@ -318,6 +318,7 @@ Unset router properties
 
     os router unset
         [--route destination=<subnet>,gateway=<ip-address>]
+        [--external-gateway]
         <router>
 
 .. option:: --route destination=<subnet>,gateway=<ip-address>
@@ -327,6 +328,10 @@ Unset router properties
     gateway: nexthop IP address
     (repeat option to unset multiple routes)
 
+.. option:: --external-gateway
+
+    Remove external gateway information from the router
+
 .. _router_unset-router:
 .. describe:: <router>
 

openstackclient/network/v2/router.py

@@ -621,6 +621,11 @@ class UnsetRouter(command.Command):
                    "destination: destination subnet (in CIDR notation) "
                    "gateway: nexthop IP address "
                    "(repeat option to unset multiple routes)"))
+        parser.add_argument(
+            '--external-gateway',
+            action='store_true',
+            default=False,
+            help=_("Remove external gateway information from the router"))
         parser.add_argument(
             'router',
             metavar="<router>",
@@ -642,5 +647,7 @@ class UnsetRouter(command.Command):
                 msg = (_("Router does not contain route %s") % route)
                 raise exceptions.CommandError(msg)
             attrs['routes'] = tmp_routes
+        if parsed_args.external_gateway:
+            attrs['external_gateway_info'] = {}
         if attrs:
             client.update_router(obj, **attrs)

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

@@ -1021,3 +1021,16 @@ class TestUnsetRouter(TestRouter):
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
         self.assertRaises(exceptions.CommandError,
                           self.cmd.take_action, parsed_args)
+
+    def test_unset_router_external_gateway(self):
+        arglist = [
+            '--external-gateway',
+            self._testrouter.name,
+        ]
+        verifylist = [('external_gateway', True)]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+        result = self.cmd.take_action(parsed_args)
+        attrs = {'external_gateway_info': {}}
+        self.network.update_router.assert_called_once_with(
+            self._testrouter, **attrs)
+        self.assertIsNone(result)

releasenotes/notes/router-gateway-set-01d9c7ffe4461daf.yaml

@@ -3,5 +3,6 @@ features:
   - |
     Add support for setting the gateway information in a router,
     by introducing the new option ``--external-gateway`` in
-    ``router set`` CLI.
+    ``router set`` command and clearing the gateway information in a router
+    by introducing ``--external-gateway`` option in ``router unset`` command.
     [ Blueprint `neutron-client-advanced-router <https://blueprints.launchpad.net/python-openstackclient/+spec/neutron-client-advanced-router>`_]