Add Thermal reference instance in chassis

Change-Id: I42309659e12c3f27a5e516cfcf0e16035fc93374

rsd_lib/resources/v2_1/chassis/chassis.py

@@ -18,6 +18,7 @@ from sushy import utils
 
 from rsd_lib.resources.v2_1.chassis import power
 from rsd_lib.resources.v2_1.chassis import power_zone
+from rsd_lib.resources.v2_1.chassis import thermal
 from rsd_lib.resources.v2_1.chassis import thermal_zone
 from rsd_lib import utils as rsd_lib_utils
 
@@ -183,6 +184,22 @@ class Chassis(base.ResourceBase):
             self._conn, self._get_thermal_zone_collection_path(),
             redfish_version=self.redfish_version)
 
+    def _get_thermal_path(self):
+        """Helper function to find the Thermal path"""
+        return utils.get_sub_resource_path_by(self, 'Thermal')
+
+    @property
+    @utils.cache_it
+    def thermal(self):
+        """Property to provide reference to `Thermal` instance
+
+        It is calculated once when it is queried for the first time. On
+        refresh, this property is reset.
+        """
+        return thermal.Thermal(
+            self._conn, self._get_thermal_path(),
+            redfish_version=self.redfish_version)
+
     def update(self, asset_tag=None, location_id=None):
         """Update AssetTag and Location->Id properties
 

rsd_lib/tests/unit/resources/v2_1/chassis/test_chassis.py

@@ -19,6 +19,7 @@ from sushy.tests.unit import base
 from rsd_lib.resources.v2_1.chassis import chassis
 from rsd_lib.resources.v2_1.chassis import power
 from rsd_lib.resources.v2_1.chassis import power_zone
+from rsd_lib.resources.v2_1.chassis import thermal
 from rsd_lib.resources.v2_1.chassis import thermal_zone
 
 
@@ -248,6 +249,59 @@ class TestChassis(base.TestCase):
         self.assertIsInstance(self.chassis_inst.thermal_zones,
                               thermal_zone.ThermalZoneCollection)
 
+    def test__get_thermal_path(self):
+        expected = '/redfish/v1/Chassis/Rack1/Thermal'
+        result = self.chassis_inst._get_thermal_path()
+        self.assertEqual(expected, result)
+
+    def test__get_thermal_path_missing_thermal_attr(self):
+        self.chassis_inst._json.pop('Thermal')
+        self.assertRaisesRegex(
+            exceptions.MissingAttributeError, 'attribute Thermal',
+            self.chassis_inst._get_thermal_path)
+
+    def test_thermal(self):
+        # | GIVEN |
+        self.conn.get.return_value.json.reset_mock()
+        with open('rsd_lib/tests/unit/json_samples/v2_1/'
+                  'thermal.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN |
+        actual_thermal = self.chassis_inst.thermal
+        # | THEN |
+        self.assertIsInstance(actual_thermal, thermal.Thermal)
+        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.assertIsInstance(actual_thermal, thermal.Thermal)
+        self.conn.get.return_value.json.assert_not_called()
+
+    def test_thermal_on_refresh(self):
+        # | GIVEN |
+        with open('rsd_lib/tests/unit/json_samples/v2_1/'
+                  'thermal.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN & THEN |
+        self.assertIsInstance(self.chassis_inst.thermal, thermal.Thermal)
+
+        # On refreshing the chassis instance...
+        with open('rsd_lib/tests/unit/json_samples/v2_1/'
+                  'chassis.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+
+        self.chassis_inst.invalidate()
+        self.chassis_inst.refresh(force=False)
+
+        # | GIVEN |
+        with open('rsd_lib/tests/unit/json_samples/v2_1/'
+                  'thermal.json', 'r') as f:
+            self.conn.get.return_value.json.return_value = json.loads(f.read())
+        # | WHEN & THEN |
+        self.assertIsInstance(self.chassis_inst.thermal, thermal.Thermal)
+
     def test_update(self):
         self.chassis_inst.update(asset_tag='Rack#1', location_id='1234')
         self.chassis_inst._conn.patch.assert_called_once_with(