Added an empty list return from parameter factories

force_bdss/mco/base_mco_factory.py

@@ -135,3 +135,4 @@ class BaseMCOFactory(HasStrictTraits):
         -------
         List of BaseMCOParameterFactory
         """
+        return []

force_bdss/mco/tests/test_base_mco_factory.py

@@ -29,6 +29,7 @@ class TestBaseMCOFactory(unittest.TestCase):
                               DummyMCOCommunicator)
         self.assertIsInstance(factory.create_model(),
                               DummyMCOModel)
+        self.assertEqual(factory.parameter_factories(), [])
 
     def test_broken_get_identifier(self):
         class Broken(DummyMCOFactory):