In InventoryList.find() raise NotFound if invalid resource class

If InventoryList.find() was provided with a string of a resource
class that does not exist it would cause an uncaught ValueError.
This would eventually raise up to the Placement API as a 500 in
response, for example, to

    'GET /resource_providers/{uuid}/inventories/HOUSE'

NotFound makes sense at both the object and HTTP levels. A unit test
for the object level has been added and a gabbi test for the HTTP
level.

Note: this was discovered while developing some test client code
for the placement API. A simple, but wrong, argument was passed
through the stack and caused a 500.

Change-Id: I0d4066a3f213f726a92d673986b702e08bda4459
Partially-Implements: blueprint generic-resource-pools

nova/objects/resource_provider.py

@@ -544,7 +544,11 @@ class InventoryList(base.ObjectListBase, base.NovaObject):
                           string.
         """
         if isinstance(res_class, six.string_types):
-            res_class = fields.ResourceClass.index(res_class)
+            try:
+                res_class = fields.ResourceClass.index(res_class)
+            except ValueError:
+                raise exception.NotFound("No such resource class '%s'" %
+                                         res_class)
 
         for inv_rec in self.objects:
             if fields.ResourceClass.index(inv_rec.resource_class) == res_class:

nova/tests/functional/api/openstack/placement/gabbits/inventory.yaml

@@ -239,6 +239,10 @@ tests:
   GET: /resource_providers/$ENVIRON['RP_UUID']/inventories/IPV4_ADDRESS
   status: 404
 
+- name: get invalid inventory class
+  GET: /resource_providers/$ENVIRON['RP_UUID']/inventories/HOUSE
+  status: 404
+
 - name: create another resource provider
   POST: /resource_providers
   request_headers:

nova/tests/unit/objects/test_resource_provider.py

@@ -435,6 +435,12 @@ class TestInventory(test_objects._LocalTest):
         self.assertIsNotNone(found)
         self.assertEqual(24, found.total)
 
+        # Use an invalid string...
+        error = self.assertRaises(exception.NotFound,
+                                  inv_list.find,
+                                  'HOUSE')
+        self.assertIn('No such resource class', str(error))
+
 
 class _TestAllocationNoDB(object):
     @mock.patch('nova.objects.Allocation._create_in_db',