Overwrite Usage class's get() function

base.Resource's get function will call its manager's get() function
with one parameter. However UsageManager's get function takes three
parameters.

Change-Id: I958a55c4d52cec4d1177371b788b3cf788098a6c
Closes-bug: 1552616

novaclient/tests/unit/v2/test_usage.py

@@ -13,6 +13,8 @@
 
 import datetime
 
+import six
+
 from novaclient.tests.unit import utils
 from novaclient.tests.unit.v2 import fakes
 from novaclient.v2 import usage
@@ -58,3 +60,18 @@ class UsageTest(utils.TestCase):
             ("start=%s&" % now.isoformat()) +
             ("end=%s" % now.isoformat()))
         self.assertIsInstance(u, usage.Usage)
+
+    def test_usage_class_get(self):
+        start = six.u('2012-01-22T19:48:41.750722')
+        stop = six.u('2012-01-22T19:48:41.750722')
+
+        info = {'tenant_id': 'tenantfoo', 'start': start,
+                'stop': stop}
+        u = usage.Usage(self.cs.usage, info)
+        u.get()
+        self.assert_request_id(u, fakes.FAKE_REQUEST_ID_LIST)
+
+        self.cs.assert_called(
+            'GET',
+            "/os-simple-tenant-usage/tenantfoo?start=%s&end=%s" %
+            (start, stop))

novaclient/v2/usage.py

@@ -15,6 +15,8 @@
 Usage interface.
 """
 
+import oslo_utils
+
 from novaclient import base
 
 
@@ -25,6 +27,19 @@ class Usage(base.Resource):
     def __repr__(self):
         return "<ComputeUsage>"
 
+    def get(self):
+        fmt = '%Y-%m-%dT%H:%M:%S.%f'
+        if self.start and self.stop and self.tenant_id:
+            # set_loaded() first ... so if we have to bail, we know we tried.
+            self.set_loaded(True)
+            start = oslo_utils.timeutils.parse_strtime(self.start, fmt=fmt)
+            stop = oslo_utils.timeutils.parse_strtime(self.stop, fmt=fmt)
+
+            new = self.manager.get(self.tenant_id, start, stop)
+            if new:
+                self._add_details(new._info)
+                self.append_request_ids(new.request_ids)
+
 
 class UsageManager(base.ManagerWithFind):
     """