diff --git a/spinoff/util/testing.py b/spinoff/util/testing.py
index <HASH>..<HASH> 100644
--- a/spinoff/util/testing.py
+++ b/spinoff/util/testing.py
@@ -197,6 +197,8 @@ class Container(MockActor):
     # from Actor, so __exit__ is not DRY etc. There might be a way to refactor Actor to allow for a more elegant
     # implementation of this class.
 
+    _actor = None
+
     def __init__(self, actor_cls=None, start_automatically=True):
         super(Container, self).__init__()
         self._actor_cls = actor_cls
Added support for 'with testing.contain(None) as (container, _)' for consistency/completeness