tests: tighten assertion in test_recv_results_metadata_no_metadata_flag_skips_metadata_id

The previous assertion used 'not hasattr(...) or ... is None' which would pass
even if the code had a bug that explicitly set result_metadata_id = None instead
of leaving the attribute absent.

result_metadata_id is not a class attribute on ResultMessage, so the correct
assertion is 'assert not hasattr(msg, "result_metadata_id")'.

column_metadata IS a class attribute (= None), so its assertion is adjusted to
'assert msg.column_metadata is None'.

Author: nikagra

tests/unit/test_protocol.py

@@ -226,8 +226,11 @@ def test_recv_results_metadata_no_metadata_flag_skips_metadata_id(self):
         )
         msg = ResultMessage(kind=RESULT_KIND_ROWS)
         msg.recv_results_metadata(buf, user_type_map={})
-        assert not hasattr(msg, 'result_metadata_id') or msg.result_metadata_id is None
-        assert not hasattr(msg, 'column_metadata') or msg.column_metadata is None
+        # recv_results_metadata returns early on NO_METADATA; result_metadata_id
+        # must never be set as an instance attribute (it is not a class default).
+        # column_metadata is a class attribute defaulting to None and must remain so.
+        assert not hasattr(msg, 'result_metadata_id')
+        assert msg.column_metadata is None
 
     def test_query_message(self):
         """