tests (unit/email gateway): add tests for pubsub service:

rel 453

tests/unit/conftest.py

@@ -67,6 +67,9 @@ class MockLiberviaBackend(LiberviaBackend):
         self.initialised = defer.Deferred()
         self.initialised.callback(None)
 
+    def get_local_path(self, *args, **kwargs):
+        return MagicMock()
+
     def get_test_config(self, section, name, default=None):
         return self._test_config.get((section or None, name), default)