'Test adding router port with multiple IPv4 subnets fails.
Multiple IPv4 subnets are not allowed on a single router port.
Ensure that adding a port with multiple IPv4 subnets to a router fails.'

def test_router_add_interface_multiple_ipv4_subnet_port_returns_400(self):

    with self.network() as n:
        with self.router() as r:
            with self.subnet(network=n, cidr='10.0.0.0/24') as s1:
                with self.subnet(network=n, cidr='10.0.1.0/24') as s2:
                    fixed_ips = [{'subnet_id': s1['subnet']['id']}, {'subnet_id': s2['subnet']['id']}]
                    orig_update_port = self.plugin.update_port
                    with self.port(subnet=s1, fixed_ips=fixed_ips) as p:
                        with mock.patch.object(self.plugin, 'update_port') as update_port:
                            update_port.side_effect = orig_update_port
                            exp_code = exc.HTTPBadRequest.code
                            body = self._router_interface_action('add', r['router']['id'], None, p['port']['id'], expected_code=exp_code)
                            self._assert_body_port_id_and_update_port(body, update_port, p['port']['id'], r['router']['id'])
