GH-91153: Move mutating index bytearray test to it's own separate test

Author: bast0006

Lib/test/test_bytes.py

@@ -1889,40 +1889,43 @@ def __index__(self):
             with self.assertRaises(IndexError):
                 self._testlimitedcapi.sequence_setitem(b, 0, Boom())
 
-        class BoomContinued:
+    def test_mutating_index_inbounds(self):
+        class MutatesOnIndex:
+            new_ba: bytearray
+
+            def __init__(self):
+                self.ba = bytearray(0x180)
+
             def __index__(self):
-                nonlocal new_ba
                 # Clear the original bytearray, mutating it during index assignment.
                 # If the internal buffers are held over this operation, they become dangling
                 # However, this will fail a bounds check as above (as the clear sets bounds to zero)
-                ba.clear()
+                self.ba.clear()
                 # At this moment, the bytearray potentially has a dangling pointer
                 # Create a new bytearray to catch any writes
-                new_ba = bytearray(0x180)
+                self.new_ba = bytearray(0x180)
                 # Ensure bounds check passes
-                ba.extend([0] * 0x180)
+                self.ba.extend([0] * 0x180)
                 return 0
 
         with self.subTest("skip_bounds_safety"):
-            new_ba: bytearray
-            ba = bytearray(0x180)
-            ba[BoomContinued()] = ord("?")
-            self.assertEqual(ba[0], ord("?"), "Assigned bytearray not altered")
-            self.assertEqual(new_ba, bytearray(0x180), "Wrong object altered")
+            instance = MutatesOnIndex()
+            instance.ba[instance] = ord("?")
+            self.assertEqual(instance.ba[0], ord("?"), "Assigned bytearray not altered")
+            self.assertEqual(instance.new_ba, bytearray(0x180), "Wrong object altered")
 
         with self.subTest("skip_bounds_safety_capi"):
-            new_ba: bytearray
-            ba = bytearray(0x180)
-            self._testlimitedcapi.sequence_setitem(ba, BoomContinued(), ord("?"))
-            self.assertEqual(ba[0], ord("?"), "Assigned bytearray not altered")
-            self.assertEqual(new_ba, bytearray(0x180), "Wrong object altered")
+            instance = MutatesOnIndex()
+            instance.ba[instance] = ord("?")
+            self._testlimitedcapi.sequence_setitem(instance.ba, instance, ord("?"))
+            self.assertEqual(instance.ba[0], ord("?"), "Assigned bytearray not altered")
+            self.assertEqual(instance.new_ba, bytearray(0x180), "Wrong object altered")
 
         with self.subTest("skip_bounds_safety_slice"):
-            new_ba: bytearray
-            ba = bytearray(0x180)
-            ba[BoomContinued():1] = [ord("?")]
-            self.assertEqual(ba[0], ord("?"), "Assigned bytearray not altered")
-            self.assertEqual(new_ba, bytearray(0x180), "Wrong object altered")
+            instance = MutatesOnIndex()
+            instance.ba[instance:1] = [ord("?")]
+            self.assertEqual(instance.ba[0], ord("?"), "Assigned bytearray not altered")
+            self.assertEqual(instance.new_ba, bytearray(0x180), "Wrong object altered")
 
 
 class AssortedBytesTest(unittest.TestCase):