diff --git a/lower-constraints.txt b/lower-constraints.txt
index 4fe56a87b..2558fe197 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -127,6 +127,7 @@ reno==2.7.0
 repoze.lru==0.7
 requests-oauthlib==0.8.0
 requests==2.14.2
+requests-mock==1.2.0
 requestsexceptions==1.4.0
 restructuredtext-lint==1.1.3
 rfc3986==1.1.0
diff --git a/tacker/tests/unit/base.py b/tacker/tests/unit/base.py
index d4f7a18bf..e17647805 100644
--- a/tacker/tests/unit/base.py
+++ b/tacker/tests/unit/base.py
@@ -16,6 +16,7 @@
 import mock
 from oslo_config import cfg
 from oslo_config import fixture as config_fixture
+from requests_mock.contrib import fixture as requests_mock_fixture
 
 from tacker.tests import base
 
@@ -32,3 +33,15 @@ class TestCase(base.BaseTestCase):
     def _mock(self, target, new=mock.DEFAULT):
         patcher = mock.patch(target, new)
         return patcher.start()
+
+
+class FixturedTestCase(TestCase):
+    client_fixture_class = None
+
+    def setUp(self):
+        super(FixturedTestCase, self).setUp()
+        if self.client_fixture_class:
+            self.requests_mock = self.useFixture(requests_mock_fixture.
+                                                 Fixture())
+            fix = self.client_fixture_class(self.requests_mock)
+            self.cs = self.useFixture(fix).client
diff --git a/tacker/tests/unit/db/utils.py b/tacker/tests/unit/db/utils.py
index 8202cfa18..89f204f25 100644
--- a/tacker/tests/unit/db/utils.py
+++ b/tacker/tests/unit/db/utils.py
@@ -129,8 +129,9 @@ def get_dummy_vnf_config_obj():
         'config': {'firewall': 'dummy_firewall_values'}}}}}}}
 
 
-def get_dummy_vnf():
-    return {'status': 'PENDING_CREATE', 'instance_id': None, 'name':
+def get_dummy_vnf(status='PENDING_CREATE', scaling_group=False,
+                  instance_id=None):
+    dummy_vnf = {'status': status, 'instance_id': instance_id, 'name':
         u'test_openwrt', 'tenant_id': u'ad7ebc56538745a08ef7c5e97f8bd437',
         'vnfd_id': u'eb094833-995e-49f0-a047-dfb56aaf7c4e',
         'vnfd': {
@@ -146,6 +147,11 @@ def get_dummy_vnf():
         'attributes': {u'param_values': u''},
         'id': 'eb84260e-5ff7-4332-b032-50a14d6c1123',
         'description': u'OpenWRT with services'}
+    if scaling_group:
+        dummy_vnf['attributes'].update({'scaling_group_names':
+                                   '{"SP1": "SP1_group"}',
+                                   'heat_template': 'test'})
+    return dummy_vnf
 
 
 def get_dummy_vnf_config_attr():
diff --git a/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/__init__.py b/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/client.py b/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/client.py
new file mode 100644
index 000000000..9ca28524b
--- /dev/null
+++ b/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/client.py
@@ -0,0 +1,56 @@
+# Copyright 2019 NTT DATA
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import fixtures
+
+from heatclient import client
+from keystoneauth1 import fixture
+from keystoneauth1 import loading
+from keystoneauth1 import session
+
+
+IDENTITY_URL = 'http://identityserver:5000/v3'
+HEAT_URL = 'http://heat-api'
+
+
+class ClientFixture(fixtures.Fixture):
+
+    def __init__(self, requests_mock, heat_url=HEAT_URL,
+                 identity_url=IDENTITY_URL):
+        super(ClientFixture, self).__init__()
+        self.identity_url = identity_url
+        self.client = None
+        self.token = fixture.V2Token()
+        self.token.set_scope()
+        self.requests_mock = requests_mock
+        self.discovery = fixture.V2Discovery(href=self.identity_url)
+        s = self.token.add_service('orchestration')
+        s.add_endpoint(heat_url)
+
+    def setUp(self):
+        super(ClientFixture, self).setUp()
+        auth_url = '%s/tokens' % self.identity_url
+        headers = {'X-Content-Type': 'application/json'}
+        self.requests_mock.post(auth_url,
+                      json=self.token, headers=headers)
+        self.requests_mock.get(self.identity_url,
+                      json=self.discovery, headers=headers)
+        self.client = self.new_client()
+
+    def new_client(self):
+        self.session = session.Session()
+        loader = loading.get_plugin_loader('password')
+        self.session.auth = loader.load_from_options(
+            auth_url=self.identity_url, username='xx', password='xx')
+        return client.Client("1", session=self.session)
diff --git a/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/fixture_data_utils.py b/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/fixture_data_utils.py
new file mode 100644
index 000000000..287b38cfa
--- /dev/null
+++ b/tacker/tests/unit/vnfm/infra_drivers/openstack/fixture_data/fixture_data_utils.py
@@ -0,0 +1,70 @@
+# Copyright 2019 NTT DATA
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from tacker.tests import uuidsentinel
+
+
+def get_dummy_stack(outputs=True, status='CREATE_COMPELETE'):
+    outputs_value = [{}]
+    if outputs:
+        outputs_value = [{'output_value': '192.168.120.216',
+                         'output_key': 'mgmt_ip-VDU1',
+                         'description': 'No description given'}]
+
+    dummy_stack = {'parent': None, 'disable_rollback': True,
+            'description': 'Demo example\n',
+            'deletion_time': None, 'stack_name':
+                'vnf-6_3f089d15-0000-4dc0-8519-a613d577a07b',
+            'stack_status_reason': 'Stack CREATE completed successfully',
+            'creation_time': '2019-02-28T15:17:48Z',
+            'outputs': outputs_value,
+            'timeout_mins': 10, 'stack_status': status,
+            'stack_owner': None,
+            'updated_time': None,
+            'id': uuidsentinel.instance_id}
+    return dummy_stack
+
+
+def get_dummy_resource(resource_status='CREATE_COMPLETE'):
+    return {'resource_name': 'SP1_group',
+            'logical_resource_id': 'SP1_group',
+            'creation_time': '2019-03-06T08:57:47Z',
+            'resource_status_reason': 'state changed',
+            'updated_time': '2019-03-06T08:57:47Z',
+            'required_by': ['SP1_scale_out', 'SP1_scale_in'],
+            'resource_status': resource_status,
+            'physical_resource_id': uuidsentinel.stack_id,
+            'attributes': {'outputs_list': None, 'refs': None,
+                           'refs_map': None, 'outputs': None,
+                           'current_size': None, 'mgmt_ip-vdu1': 'test1'},
+            'resource_type': 'OS::Heat::AutoScalingGroup'}
+
+
+def get_dummy_event(resource_status='CREATE_COMPLETE'):
+    return {'resource_name': 'SP1_scale_out',
+            'event_time': '2019-03-06T05:44:27Z',
+            'logical_resource_id': 'SP1_scale_out',
+            'resource_status': resource_status,
+            'resource_status_reason': 'state changed',
+            'id': uuidsentinel.event_id}
+
+
+def get_dummy_policy_dict():
+    return {'instance_id': uuidsentinel.instance_id,
+            'vnf': {'attributes': {'scaling_group_names': '{"SP1": "G1"}'},
+                    'id': uuidsentinel.vnf_id},
+            'name': 'SP1',
+            'action': 'out',
+            'type': 'tosca.policies.tacker.Scaling',
+            'properties': {}}
diff --git a/tacker/tests/unit/vnfm/infra_drivers/openstack/test_openstack_driver.py b/tacker/tests/unit/vnfm/infra_drivers/openstack/test_openstack_driver.py
index 43b8c400e..0125df997 100644
--- a/tacker/tests/unit/vnfm/infra_drivers/openstack/test_openstack_driver.py
+++ b/tacker/tests/unit/vnfm/infra_drivers/openstack/test_openstack_driver.py
@@ -13,29 +13,293 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import ddt
 import mock
 
+from tacker import context
 from tacker.extensions import vnfm
 from tacker.tests.unit import base
+from tacker.tests.unit.db import utils
+from tacker.tests.unit.vnfm.infra_drivers.openstack.fixture_data import client
+from tacker.tests.unit.vnfm.infra_drivers.openstack.fixture_data import \
+    fixture_data_utils as fd_utils
+from tacker.tests import uuidsentinel
 from tacker.vnfm.infra_drivers.openstack import openstack
 
 
-class TestOpenStack(base.TestCase):
+@ddt.ddt
+class TestOpenStack(base.FixturedTestCase):
+    client_fixture_class = client.ClientFixture
 
-    @mock.patch("tacker.vnfm.infra_drivers.openstack.heat_client.HeatClient")
-    def test_create_wait_with_heat_connection_exception(self, mocked_hc):
-        stack = {"stack_status", "CREATE_IN_PROGRESS"}
-        mocked_hc.get.side_effect = [stack, Exception("any stuff")]
-        openstack_driver = openstack.OpenStack()
+    def setUp(self):
+        super(TestOpenStack, self).setUp()
+        self.openstack = openstack.OpenStack()
+        self.context = context.get_admin_context()
+        self.url = client.HEAT_URL
+        self.instance_uuid = uuidsentinel.instance_id
+        self.stack_id = uuidsentinel.stack_id
+        self.json_headers = {'content-type': 'application/json',
+                             'location': 'http://heat-api/stacks/'
+                             + self.instance_uuid + '/myStack/60f83b5e'}
+        self._mock('tacker.common.clients.OpenstackClients.heat', self.cs)
+        self.mock_log = mock.patch('tacker.vnfm.infra_drivers.openstack.'
+                                   'openstack.LOG').start()
+        mock.patch('time.sleep', return_value=None).start()
+
+    def _response_in_wait_until_stack_ready(self, status_list,
+                                            stack_outputs=True):
+        # response for heat_client's get()
+        for status in status_list:
+            url = self.url + '/stacks/' + self.instance_uuid
+            json = {'stack': fd_utils.get_dummy_stack(stack_outputs,
+                                                      status=status)}
+            self.requests_mock.register_uri('GET', url, json=json,
+                                            headers=self.json_headers)
+
+    def _response_in_resource_get(self, id, res_name=None):
+        # response for heat_client's resource_get()
+        if res_name:
+            url = self.url + '/stacks/' + id + ('/myStack/60f83b5e/'
+                                                'resources/') + res_name
+        else:
+            url = self.url + '/stacks/' + id
+
+        json = {'resource': fd_utils.get_dummy_resource()}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+
+    def test_create_wait(self):
+        self._response_in_wait_until_stack_ready(["CREATE_IN_PROGRESS",
+                                                 "CREATE_COMPLETE"])
+        vnf_dict = utils.get_dummy_vnf(instance_id=self.instance_uuid)
+        self.openstack.create_wait(None, None,
+                                   vnf_dict, self.instance_uuid, None)
+        self.mock_log.debug.assert_called_with('outputs %s',
+                                         fd_utils.get_dummy_stack()['outputs'])
+        self.assertEqual('{"VDU1": "192.168.120.216"}',
+                         vnf_dict['mgmt_ip_address'])
+
+    def test_create_wait_without_mgmt_ips(self):
+        self._response_in_wait_until_stack_ready(["CREATE_IN_PROGRESS",
+                                                 "CREATE_COMPLETE"],
+                                                 stack_outputs=False)
+        vnf_dict = utils.get_dummy_vnf(instance_id=self.instance_uuid)
+        self.openstack.create_wait(None, None,
+                                   vnf_dict, self.instance_uuid, None)
+        self.mock_log.debug.assert_called_with('outputs %s',
+                          fd_utils.get_dummy_stack(outputs=False)['outputs'])
+        self.assertIsNone(vnf_dict['mgmt_ip_address'])
+
+    def test_create_wait_with_scaling_group_names(self):
+        self._response_in_wait_until_stack_ready(["CREATE_IN_PROGRESS",
+                                                 "CREATE_COMPLETE"])
+        self._response_in_resource_get(self.instance_uuid,
+                                       res_name='SP1_group')
+        url = self.url + '/stacks/' + self.stack_id + '/resources'
+        json = {'resources': [fd_utils.get_dummy_resource()]}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+        self._response_in_resource_get(self.stack_id)
+        vnf_dict = utils.get_dummy_vnf(scaling_group=True)
+        self.openstack.create_wait(None, None, vnf_dict, self.instance_uuid,
+                                   None)
+        self.assertEqual('{"vdu1": ["test1"]}', vnf_dict['mgmt_ip_address'])
+
+    def test_create_wait_failed_with_stack_retries_0(self):
+        self._response_in_wait_until_stack_ready(["CREATE_IN_PROGRESS"])
+        vnf_dict = utils.get_dummy_vnf(instance_id=self.instance_uuid)
         self.assertRaises(vnfm.VNFCreateWaitFailed,
-                          openstack_driver.create_wait,
-                          None, None, {}, 'vnf_id', None)
+                          self.openstack.create_wait,
+                          None, None, vnf_dict, self.instance_uuid, None)
 
-    @mock.patch("tacker.vnfm.infra_drivers.openstack.heat_client.HeatClient")
-    def test_delete_wait_with_heat_connection_exception(self, mocked_hc):
-        stack = {"stack_status", "DELETE_IN_PROGRESS"}
-        mocked_hc.get.side_effect = [stack, Exception("any stuff")]
-        openstack_driver = openstack.OpenStack()
+    def test_create_wait_failed_with_stack_retries_not_0(self):
+        self._response_in_wait_until_stack_ready(["CREATE_IN_PROGRESS",
+                                                 "FAILED"])
+        vnf_dict = utils.get_dummy_vnf(instance_id=self.instance_uuid)
+        self.assertRaises(vnfm.VNFCreateWaitFailed,
+                          self.openstack.create_wait,
+                          None, None, vnf_dict, self.instance_uuid, {})
+
+    def _exception_response(self):
+        url = self.url + '/stacks/' + self.instance_uuid
+        body = {"error": Exception("any stuff")}
+        self.requests_mock.register_uri('GET', url, body=body,
+                    status_code=404, headers=self.json_headers)
+
+    def test_create_wait_with_exception(self):
+        self._exception_response()
+        vnf_dict = utils.get_dummy_vnf(instance_id=self.instance_uuid)
+        self.assertRaises(vnfm.VNFCreateWaitFailed,
+                          self.openstack.create_wait,
+                          None, None, vnf_dict, self.instance_uuid, None)
+
+    def test_delete_wait_failed_with_stack_retries_0(self):
+        self._response_in_wait_until_stack_ready(["DELETE_IN_PROGRESS"])
         self.assertRaises(vnfm.VNFDeleteWaitFailed,
-                          openstack_driver.delete_wait,
-                          None, None, 'vnf_id', None, None)
+                          self.openstack.delete_wait,
+                          None, None, self.instance_uuid, None, None)
+
+    def test_delete_wait_stack_retries_not_0(self):
+        self._response_in_wait_until_stack_ready(["DELETE_IN_PROGRESS",
+                                                 "FAILED"])
+        self.assertRaises(vnfm.VNFDeleteWaitFailed,
+                          self.openstack.delete_wait,
+                          None, None, self.instance_uuid, None, None)
+        self.mock_log.warning.assert_called_once()
+
+    def test_update_wait(self):
+        self._response_in_wait_until_stack_ready(["UPDATE_IN_PROGRESS",
+                                                 "UPDATE_COMPLETE"])
+        vnf_dict = utils.get_dummy_vnf(status='PENDING_UPDATE',
+                                       instance_id=self.instance_uuid)
+        self.openstack.update_wait(None, None, vnf_dict, None)
+        self.mock_log.debug.assert_called_with('outputs %s',
+                                    fd_utils.get_dummy_stack()['outputs'])
+        self.assertEqual('{"VDU1": "192.168.120.216"}',
+                         vnf_dict['mgmt_ip_address'])
+
+    def test_update_wait_without_mgmt_ips(self):
+        self._response_in_wait_until_stack_ready(["UPDATE_IN_PROGRESS",
+                                                  "UPDATE_COMPLETE"],
+                                                 stack_outputs=False)
+        vnf_dict = utils.get_dummy_vnf(status='PENDING_UPDATE',
+                                       instance_id=self.instance_uuid)
+        self.openstack.update_wait(None, None, vnf_dict, None)
+        self.mock_log.debug.assert_called_with('outputs %s',
+                        fd_utils.get_dummy_stack(outputs=False)['outputs'])
+        self.assertIsNone(vnf_dict['mgmt_ip_address'])
+
+    def test_update_wait_failed_with_retries_0(self):
+        self._response_in_wait_until_stack_ready(["UPDATE_IN_PROGRESS"])
+        vnf_dict = utils.get_dummy_vnf(status='PENDING_UPDATE',
+                                       instance_id=self.instance_uuid)
+        self.assertRaises(vnfm.VNFUpdateWaitFailed,
+                          self.openstack.update_wait,
+                          None, None, vnf_dict,
+                          None)
+
+    def test_update_wait_failed_stack_retries_not_0(self):
+        self._response_in_wait_until_stack_ready(["UPDATE_IN_PROGRESS",
+                                                 "FAILED"])
+        vnf_dict = utils.get_dummy_vnf(status='PENDING_UPDATE',
+                                       instance_id=self.instance_uuid)
+        self.assertRaises(vnfm.VNFUpdateWaitFailed,
+                          self.openstack.update_wait,
+                          None, None, vnf_dict,
+                          None)
+
+    def _responses_in_resource_event_list(self, dummy_event):
+        # response for heat_client's resource_event_list()
+        url = self.url + '/stacks/' + self.instance_uuid
+        json = {'stack': [fd_utils.get_dummy_stack()]}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+        url = self.url + '/stacks/' + self.instance_uuid + ('/myStack/60f83b5e'
+        '/resources/SP1_scale_out/events?limit=1&sort_dir=desc&sort_keys='
+        'event_time')
+        json = {'events': [dummy_event]}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+
+    def test_scale(self):
+        dummy_event = fd_utils.get_dummy_event()
+        self._responses_in_resource_event_list(dummy_event)
+        # response for heat_client's resource_signal()
+        url = self.url + '/stacks/' + self.instance_uuid + ('/myStack/60f83b5e'
+                                             '/resources/SP1_scale_out/signal')
+        self.requests_mock.register_uri('POST', url, json={},
+                                        headers=self.json_headers)
+        event_id = self.openstack.scale(plugin=self, context=self.context,
+                                    auth_attr=None,
+                                    policy=fd_utils.get_dummy_policy_dict(),
+                                    region_name=None)
+        self.assertEqual(dummy_event['id'], event_id)
+
+    def _response_in_resource_get_list(self):
+        # response for heat_client's resource_get_list()
+        url = self.url + '/stacks/' + self.stack_id + '/resources'
+        json = {'resources': [fd_utils.get_dummy_resource()]}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+
+    def _test_scale(self, resource_status):
+        dummy_event = fd_utils.get_dummy_event(resource_status)
+        self._responses_in_resource_event_list(dummy_event)
+        self._response_in_resource_get(self.instance_uuid, res_name='G1')
+        self._response_in_resource_get_list()
+        self._response_in_resource_get(self.stack_id)
+        self._response_in_resource_get(self.instance_uuid,
+                                       res_name='SP1_group')
+
+    def test_scale_wait_with_different_last_event_id(self):
+        self._test_scale("SIGNAL_COMPLETE")
+        mgmt_ip = self.openstack.scale_wait(plugin=self, context=self.context,
+                                     auth_attr=None,
+                                     policy=fd_utils.get_dummy_policy_dict(),
+                                     region_name=None,
+                                     last_event_id=uuidsentinel.
+                                            non_last_event_id)
+        self.assertEqual('{"vdu1": ["test1"]}', mgmt_ip)
+
+    @ddt.data("SIGNAL_COMPLETE", "CREATE_COMPLETE")
+    def test_scale_wait_with_same_last_event_id(self, resource_status):
+        self._test_scale(resource_status)
+        mgmt_ip = self.openstack.scale_wait(plugin=self,
+                                context=self.context,
+                                auth_attr=None,
+                                policy=fd_utils.get_dummy_policy_dict(),
+                                region_name=None,
+                                last_event_id=fd_utils.get_dummy_event()['id'])
+        self.assertEqual('{"vdu1": ["test1"]}', mgmt_ip)
+
+    @mock.patch('tacker.vnfm.infra_drivers.openstack.openstack.LOG')
+    def test_scale_wait_failed_with_exception(self, mock_log):
+        self._exception_response()
+        self.assertRaises(vnfm.VNFScaleWaitFailed,
+                          self.openstack.scale_wait,
+                          plugin=self, context=self.context, auth_attr=None,
+                          policy=fd_utils.get_dummy_policy_dict(),
+                          region_name=None,
+                          last_event_id=fd_utils.get_dummy_event()['id'])
+        mock_log.warning.assert_called_once()
+
+    def _response_in_resource_metadata(self, metadata=None):
+        # response for heat_client's resource_metadata()
+        url = self.url + '/stacks/' + self.instance_uuid + \
+            '/myStack/60f83b5e/resources/SP1_scale_out/metadata'
+        json = {'metadata': {'scaling_in_progress': metadata}}
+        self.requests_mock.register_uri('GET', url, json=json,
+                                        headers=self.json_headers)
+
+    def test_scale_wait_failed_with_stack_retries_0(self):
+        dummy_event = fd_utils.get_dummy_event("CREATE_IN_PROGRESS")
+        self._responses_in_resource_event_list(dummy_event)
+        self._response_in_resource_metadata(True)
+        self.assertRaises(vnfm.VNFScaleWaitFailed,
+                          self.openstack.scale_wait,
+                          plugin=self, context=self.context, auth_attr=None,
+                          policy=fd_utils.get_dummy_policy_dict(),
+                          region_name=None,
+                          last_event_id=dummy_event['id'])
+        self.mock_log.warning.assert_called_once()
+
+    def test_scale_wait_without_resource_metadata(self):
+        dummy_event = fd_utils.get_dummy_event("CREATE_IN_PROGRESS")
+        self._responses_in_resource_event_list(dummy_event)
+        self._response_in_resource_metadata()
+        self._response_in_resource_get(self.instance_uuid, res_name='G1')
+        self._response_in_resource_get_list()
+        self._response_in_resource_get(self.stack_id)
+        self._response_in_resource_get(self.instance_uuid,
+                                       res_name='SP1_group')
+        mgmt_ip = self.openstack.scale_wait(plugin=self, context=self.context,
+                                  auth_attr=None,
+                                  policy=fd_utils.get_dummy_policy_dict(),
+                                  region_name=None,
+                                  last_event_id=fd_utils.get_dummy_event()
+                                  ['id'])
+        error_reason = ('When signal occurred within cool down '
+                        'window, no events generated from heat, '
+                        'so ignore it')
+        self.mock_log.warning.assert_called_once_with(error_reason)
+        self.assertEqual('{"vdu1": ["test1"]}', mgmt_ip)
diff --git a/tacker/tests/uuidsentinel.py b/tacker/tests/uuidsentinel.py
new file mode 100644
index 000000000..9dae89667
--- /dev/null
+++ b/tacker/tests/uuidsentinel.py
@@ -0,0 +1,33 @@
+# Copyright 2019 NTT DATA
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import sys
+
+
+class UUIDSentinels(object):
+    def __init__(self):
+        from oslo_utils import uuidutils
+        self._uuid_module = uuidutils
+        self._sentinels = {}
+
+    def __getattr__(self, name):
+        if name.startswith('_'):
+            raise ValueError('Sentinels must not start with _')
+        if name not in self._sentinels:
+            self._sentinels[name] = self._uuid_module.generate_uuid()
+        return self._sentinels[name]
+
+
+sys.modules[__name__] = UUIDSentinels()
diff --git a/tacker/vnfm/infra_drivers/openstack/openstack.py b/tacker/vnfm/infra_drivers/openstack/openstack.py
index e0548b7a8..4dc21ed5d 100644
--- a/tacker/vnfm/infra_drivers/openstack/openstack.py
+++ b/tacker/vnfm/infra_drivers/openstack/openstack.py
@@ -180,13 +180,7 @@ class OpenStack(abstract_driver.VnfAbstractDriver,
                     stack=vnf_id)
                 raise exception_class(reason=error_reason)
             elif stack_retries != 0 and status != wait_status:
-                if stack:
-                    error_reason = stack.stack_status_reason
-                else:
-                    error_reason = _("action on VNF %(vnf_id)s is not "
-                                     "completed. Current status of stack is "
-                                     "%(stack_status)s") % {'vnf_id': vnf_id,
-                                     'stack_status': status}
+                error_reason = stack.stack_status_reason
                 LOG.warning(error_reason)
                 raise exception_class(reason=error_reason)
 
diff --git a/test-requirements.txt b/test-requirements.txt
index 442e5a463..6d15758ad 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -19,3 +19,4 @@ testtools>=2.2.0 # MIT
 WebTest>=2.0.27 # MIT
 python-barbicanclient>=4.5.2 # Apache-2.0
 python-blazarclient>=1.0.1 # Apache-2.0
+requests-mock>=1.2.0 # Apache-2.0
\ No newline at end of file