Add response schema validation for volume extensions

This is to add response schema validation for volume
extensions.

Change-Id: I652ac1e2fa5d614b1207b3cbb300e89a38217443
partially-implements: blueprint volume-response-schema-validation
diff --git a/tempest/lib/api_schema/response/volume/extensions.py b/tempest/lib/api_schema/response/volume/extensions.py
new file mode 100644
index 0000000..8dcb07d
--- /dev/null
+++ b/tempest/lib/api_schema/response/volume/extensions.py
@@ -0,0 +1,43 @@
+# Copyright 2018 ZTE Corporation.  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.
+
+from tempest.lib.api_schema.response.compute.v2_1 import parameter_types
+
+list_extensions = {
+    'status_code': [200],
+    'response_body': {
+        'type': 'object',
+        'properties': {
+            'extensions': {
+                'type': 'array',
+                'items': {
+                    'type': 'object',
+                    'properties': {
+                        'updated': parameter_types.date_time,
+                        'description': {'type': 'string'},
+                        'links': {'type': 'array'},
+                        'namespace': {'type': 'string'},
+                        'alias': {'type': 'string'},
+                        'name': {'type': 'string'}
+                    },
+                    'additionalProperties': False,
+                    'required': ['updated', 'links', 'alias', 'name',
+                                 'description']
+                }
+            }
+        },
+        'additionalProperties': False,
+        'required': ['extensions'],
+    }
+}
diff --git a/tempest/lib/services/volume/v3/extensions_client.py b/tempest/lib/services/volume/v3/extensions_client.py
index 45b7a56..f1fe5c9 100644
--- a/tempest/lib/services/volume/v3/extensions_client.py
+++ b/tempest/lib/services/volume/v3/extensions_client.py
@@ -15,6 +15,7 @@
 
 from oslo_serialization import jsonutils as json
 
+from tempest.lib.api_schema.response.volume import extensions as schema
 from tempest.lib.common import rest_client
 
 
@@ -25,5 +26,5 @@
         url = 'extensions'
         resp, body = self.get(url)
         body = json.loads(body)
-        self.expected_success(200, resp.status)
+        self.validate_response(schema.list_extensions, resp, body)
         return rest_client.ResponseBody(resp, body)