gh-102947: Improve traceback when calling `fields()` on a non-dataclass (GH-102948)

(cherry picked from commit baf4eb083c09b323cc12b8636c28c14089b87de8)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 3a24777..abe02e3 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -5,11 +5,13 @@
 from dataclasses import *
 
 import abc
+import io
 import pickle
 import inspect
 import builtins
 import types
 import weakref
+import traceback
 import unittest
 from unittest.mock import Mock
 from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional, Protocol
@@ -1500,6 +1502,16 @@ class TestCase(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, 'dataclass type or instance'):
             fields(C())
 
+    def test_clean_traceback_from_fields_exception(self):
+        stdout = io.StringIO()
+        try:
+            fields(object)
+        except TypeError as exc:
+            traceback.print_exception(exc, file=stdout)
+        printed_traceback = stdout.getvalue()
+        self.assertNotIn("AttributeError", printed_traceback)
+        self.assertNotIn("__dataclass_fields__", printed_traceback)
+
     def test_helper_asdict(self):
         # Basic tests for asdict(), it should return a new dictionary.
         @dataclass