Add volume reference instance in storage service

Change-Id: I3e625b40f7b1a4b396ca059b0e069196c80ca073

rsd_lib/resources/v2_3/storage_service/storage_service.py

@@ -15,8 +15,12 @@
 
 import logging
 
+from sushy import exceptions
 from sushy.resources import base
 
+from rsd_lib.resources.v2_3.storage_service import volume
+from rsd_lib import utils
+
 LOG = logging.getLogger(__name__)
 
 
@@ -40,6 +44,8 @@ class StorageService(base.ResourceBase):
     status = StatusField('Status')
     """The storage service status"""
 
+    _volumes = None  # ref to Volumes instance
+
     def __init__(self, connector, identity, redfish_version=None):
         """A class representing a StorageService
 
@@ -51,6 +57,32 @@ class StorageService(base.ResourceBase):
         super(StorageService, self).__init__(connector, identity,
                                              redfish_version)
 
+    def _get_volume_collection_path(self):
+        """Helper function to find the VolumeCollection path"""
+        volume_col = self.json.get('Volumes')
+        if not volume_col:
+            raise exceptions.MissingAttributeError(attribute='Volumes',
+                                                   resource=self._path)
+        return utils.get_resource_identity(volume_col)
+
+    @property
+    def volumes(self):
+        """Property to provide reference to `VolumeCollection` instance
+
+        It is calculated once when it is queried for the first time. On
+        refresh, this property is reset.
+        """
+        if self._volumes is None:
+            self._volumes = volume.VolumeCollection(
+                self._conn, self._get_volume_collection_path(),
+                redfish_version=self.redfish_version)
+
+        return self._volumes
+
+    def refresh(self):
+        super(StorageService, self).refresh()
+        self._volumes = None
+
 
 class StorageServiceCollection(base.ResourceCollectionBase):
 

rsd_lib/tests/unit/resources/v2_3/storage_service/test_storage_service.py

@@ -14,11 +14,13 @@
 #    under the License.
 
 import json
-
 import mock
 import testtools
 
+from sushy import exceptions
+
 from rsd_lib.resources.v2_3.storage_service import storage_service
+from rsd_lib.resources.v2_3.storage_service import volume
 
 
 class StorageServiceTestCase(testtools.TestCase):
@@ -44,6 +46,67 @@ class StorageServiceTestCase(testtools.TestCase):
         self.assertEqual('Enabled', self.storage_service_inst.status.state)
         self.assertEqual('OK', self.storage_service_inst.status.health)
         self.assertEqual('OK', self.storage_service_inst.status.health_rollup)
+        self.assertIsNone(self.storage_service_inst._volumes)
+
+    def test__get_volume_collection_path(self):
+        expected = '/redfish/v1/StorageServices/1/Volumes'
+        result = self.storage_service_inst._get_volume_collection_path()
+        self.assertEqual(expected, result)
+
+    def test__get_volume_collection_path_missing_processors_attr(self):
+        self.storage_service_inst._json.pop('Volumes')
+        self.assertRaisesRegex(
+            exceptions.MissingAttributeError, 'attribute Volumes',
+            self.storage_service_inst._get_volume_collection_path)
+
+    def test_volumes(self):
+        # check for the underneath variable value
+        self.assertIsNone(self.storage_service_inst._volumes)
+        # | GIVEN |
+        self.conn.get.return_value.json.reset_mock()
+        with open('rsd_lib/tests/unit/json_samples/v2_3/'
+                  'volume_collection.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN |
+        actual_volumes = self.storage_service_inst.volumes
+        # | THEN |
+        self.assertIsInstance(actual_volumes,
+                              volume.VolumeCollection)
+        self.conn.get.return_value.json.assert_called_once_with()
+
+        # reset mock
+        self.conn.get.return_value.json.reset_mock()
+        # | WHEN & THEN |
+        # tests for same object on invoking subsequently
+        self.assertIs(actual_volumes,
+                      self.storage_service_inst.volumes)
+        self.conn.get.return_value.json.assert_not_called()
+
+    def test_volumes_on_refresh(self):
+        # | GIVEN |
+        with open('rsd_lib/tests/unit/json_samples/v2_3/'
+                  'volume_collection.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN & THEN |
+        self.assertIsInstance(self.storage_service_inst.volumes,
+                              volume.VolumeCollection)
+
+        # On refreshing the storage service instance...
+        with open('rsd_lib/tests/unit/json_samples/v2_3/'
+                  'storage_service.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        self.storage_service_inst.refresh()
+
+        # | WHEN & THEN |
+        self.assertIsNone(self.storage_service_inst._volumes)
+
+        # | GIVEN |
+        with open('rsd_lib/tests/unit/json_samples/v2_3/'
+                  'volume_collection.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN & THEN |
+        self.assertIsInstance(self.storage_service_inst.volumes,
+                              volume.VolumeCollection)
 
 
 class StorageServiceCollectionTestCase(testtools.TestCase):