Update Lib/test/test_itertools.py

Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: VanshAgarwal24036

Lib/test/test_itertools.py

@@ -734,17 +734,25 @@ def keyfunc(obj):
         self.assertRaises(ExpectedError, gulp, [None, None], keyfunc)
 
     def test_groupby_reentrant_eq_does_not_crash(self):
-        class Key(bytearray):
-            seen = False
+        # regression test for gh-143543
+        class Key:
+            def __init__(self, do_advance):
+                self.do_advance = do_advance
+
             def __eq__(self, other):
-                if not Key.seen:
-                    Key.seen = True
+                if self.do_advance:
+                    self.do_advance = False
                     next(g)
+                    return NotImplemented
                 return False
 
-        g = itertools.groupby([Key(b"a"), Key(b"b")])
+        def keys():
+            yield Key(True)
+            yield Key(False)
+
+        g = itertools.groupby([None, None], keys().send)
         next(g)
-        next(g)  # must not segfault
+        next(g)  # must pass with address sanitizer
 
     def test_filter(self):
         self.assertEqual(list(filter(isEven, range(6))), [0,2,4])