diff --git a/trytond/trytond/tests/test_tryton.py b/trytond/trytond/tests/test_tryton.py
index 7b45d99c64..f018c6fb19 100644
--- a/trytond/trytond/tests/test_tryton.py
+++ b/trytond/trytond/tests/test_tryton.py
@@ -888,8 +888,9 @@ class ModuleTestCase(_DBTestCase):
                                 'field': field_name,
                                 })
                         if func_name == field.searcher:
-                            getattr(model, field.searcher)(
+                            domain = getattr(model, field.searcher)(
                                 field_name, (field_name, '=', None))
+                            self.assertIsInstance(domain, list)
 
     @with_transaction()
     def test_ir_action_window(self):