Fix UT exception

Eliminate messages: 'NoneType' object has no attribute '__getitem__'

Change-Id: Icd57ee77cfc0e24a80ba926f7de6ac8ffccec92d

gbpservice/neutron/services/servicechain/plugins/ncp/node_drivers/dummy_driver.py

@@ -79,4 +79,4 @@ class NoopNodeDriver(driver_base.NodeDriverBase):
 
     @log.log_method_call
     def get_status(self, context):
-        pass
+        return {'status': '', 'status_details': ''}

gbpservice/neutron/tests/unit/services/grouppolicy/test_resource_mapping.py

@@ -3281,7 +3281,11 @@ class TestServiceChain(ResourceMappingTestCase):
             expected_provider_ptg_ids = set([provider_ptg, provider_ptg_new])
             self.assertEqual(expected_provider_ptg_ids,
                              sc_instances_provider_ptg_ids)
-            self.assertEqual([], sc_instance_update.call_args_list)
+            # verify all update calls are on new instances only
+            new_instance_ids = [inst['id'] for inst in sc_instances_new]
+            for call in sc_instance_update.call_args_list:
+                args, kwargs = call
+                self.assertIn(args[1], new_instance_ids)
 
     # This test is being skipped because the NCP plugin does not support
     # multiple servicechain_specs per servicechain_instance