Fix ExtensionApi interface

tests/test_base_extension.py

@@ -23,7 +23,8 @@ class BaseExtensionTestSuite(unittest.TestCase):
             type_loader=TypeLoaderMock(self.type_registry),
             action_registry=Dummy('ActionRegistry'),
             document_registry=Dummy('DocumentRegistry'),
-            document_factory=Dummy('DocumentFactory')
+            document_factory=Dummy('DocumentFactory'),
+            ui_service_registry=Dummy('UiServiceRegistry'),
         )
 
     def test_create_base_extension(self):