Tempest test tempest.api.network.test_routers.RoutersIpV6Test.test_update_router_set_gateway fails

[Vedamurthy Joshi]

R3.0.2.0 Build 52 Liberty

Tempest test tempest.api.network.test_routers.RoutersIpV6Test.test_update_router_set_gateway fails with below error.
The test expects that once the router is updated with external gateway VN, a port gets created from that VN with device-id of the router

But in contrail, it does not happen then.
It happens only when an interface is added to the router using router-interface-add. This test does not do router-interface-add

Traceback (most recent call last):
  File "tempest/api/network/test_routers.py", line 210, in test_update_router_set_gateway
    self._verify_gateway_port(router['id'])
  File "tempest/api/network/test_routers.py", line 189, in _verify_gateway_port
    self.assertEqual(len(list_body['ports']), 1)
  File "/root/.rally/tempest/for-deployment-7119472f-586e-473d-b3d2-51cdaa441f9c/.venv/lib/python2.7/site-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/root/.rally/tempest/for-deployment-7119472f-586e-473d-b3d2-51cdaa441f9c/.venv/lib/python2.7/site-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 0 != 1

-------------

Related test code :

    def _verify_gateway_port(self, router_id):
        list_body = self.admin_ports_client.list_ports(
            network_id=CONF.network.public_network_id,
            device_id=router_id)
        self.assertEqual(len(list_body['ports']), 1)
        gw_port = list_body['ports'][0]
        fixed_ips = gw_port['fixed_ips']
        self.assertGreaterEqual(len(fixed_ips), 1)
        public_net_body = self.admin_networks_client.show_network(
            CONF.network.public_network_id)
        public_subnet_id = public_net_body['network']['subnets'][0]
        self.assertIn(public_subnet_id,
                      map(lambda x: x['subnet_id'], fixed_ips))

    @test.idempotent_id('6cc285d8-46bf-4f36-9b1a-783e3008ba79')
    def test_update_router_set_gateway(self):
        router = self._create_router(data_utils.rand_name('router-'))
        self.routers_client.update_router(
            router['id'],
            external_gateway_info={
                'network_id': CONF.network.public_network_id})
        # Verify operation - router
        import pdb; pdb.set_trace()
        self._verify_router_gateway(
            router['id'],
            {'network_id': CONF.network.public_network_id})
        self._verify_gateway_port(router['id'])