Updating error message in xproto

Change-Id: I21ff9746e61f83d83c7cc64c452913d1299b49f9
diff --git a/lib/xos-genx/xos-genx-tests/test_tosca.py b/lib/xos-genx/xos-genx-tests/test_tosca.py
index 6807028..0d2ec4e 100644
--- a/lib/xos-genx/xos-genx-tests/test_tosca.py
+++ b/lib/xos-genx/xos-genx-tests/test_tosca.py
@@ -57,7 +57,7 @@
         self.target_tosca_keys = XProtoTestHelpers.write_tmp_target(
             """
             {%- for m in proto.messages %}
-                {{ xproto_fields_to_tosca_keys(m.fields) }}
+                {{ xproto_fields_to_tosca_keys(m.fields, m) }}
             {% endfor -%}
             """)