Correct a misuse of RestController in the Event API

When nested RestControllers exist, in order to determine which
arguments are associated with the parent resource, pecan looks at the
get_one() method signature in the parent controller.

TraitsController needs the EventTypesController.get_one method to exist in
order to properly pass the `event_type` identifier.

Change-Id: Ic1704c8f9c810ada4e22e8de75ef2511006e8d9d

ceilometer/api/controllers/v2.py

@@ -1797,12 +1797,13 @@ class EventTypesController(rest.RestController):
 
     traits = TraitsController()
 
-    # FIXME(herndon): due to a bug in pecan, making this method
-    # get_all instead of get will hide the traits subcontroller.
-    # https://bugs.launchpad.net/pecan/+bug/1262277
+    @pecan.expose()
+    def get_one(self, event_type):
+        pecan.abort(404)
+
     @requires_admin
     @wsme_pecan.wsexpose([unicode])
-    def get(self):
+    def get_all(self):
         """Get all event types.
         """
         return list(pecan.request.storage_conn.get_event_types())

ceilometer/tests/api/v2/test_event_scenarios.py

@@ -84,6 +84,11 @@ class TestTraitAPI(EventTestBase):
 
         self.assertEqual(4, len(data))
 
+    def test_get_event_invalid_path(self):
+        data = self.get_json('/event_types/trait_A/', headers=headers,
+                             expect_errors=True)
+        self.assertEqual(404, data.status_int)
+
     def test_get_traits_for_non_existent_event(self):
         path = self.PATH % "NO_SUCH_EVENT_TYPE"
         data = self.get_json(path, headers=headers)