gh-92118: fix traceback of exceptions propagated from inside a contextlib.contextmanager (GH-92202)

Lib/test/test_contextlib.py

@@ -5,6 +5,7 @@ import os
 import sys
 import tempfile
 import threading
+import traceback
 import unittest
 from contextlib import *  # Tests __all__
 from test import support
@@ -87,6 +88,32 @@ class ContextManagerTestCase(unittest.TestCase):
                 raise ZeroDivisionError()
         self.assertEqual(state, [1, 42, 999])
 
+    def test_contextmanager_traceback(self):
+        @contextmanager
+        def f():
+            yield
+
+        try:
+            with f():
+                1/0
+        except ZeroDivisionError as e:
+            frames = traceback.extract_tb(e.__traceback__)
+
+        self.assertEqual(len(frames), 1)
+        self.assertEqual(frames[0].name, 'test_contextmanager_traceback')
+        self.assertEqual(frames[0].line, '1/0')
+
+        # Repeat with RuntimeError (which goes through a different code path)
+        try:
+            with f():
+                raise NotImplementedError(42)
+        except NotImplementedError as e:
+            frames = traceback.extract_tb(e.__traceback__)
+
+        self.assertEqual(len(frames), 1)
+        self.assertEqual(frames[0].name, 'test_contextmanager_traceback')
+        self.assertEqual(frames[0].line, 'raise NotImplementedError(42)')
+
     def test_contextmanager_no_reraise(self):
         @contextmanager
         def whee():