Address code review

Author: corona10

Lib/test/test_opcache.py

@@ -1808,6 +1808,27 @@ def binary_subscr_dict():
         self.assert_specialized(binary_subscr_dict, "BINARY_OP_SUBSCR_DICT")
         self.assert_no_opcode(binary_subscr_dict, "BINARY_OP")
 
+        def binary_subscr_frozen_dict():
+            for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
+                a = frozendict({1: 2, 2: 3})
+                self.assertEqual(a[1], 2)
+                self.assertEqual(a[2], 3)
+
+        binary_subscr_frozen_dict()
+        self.assert_specialized(binary_subscr_frozen_dict, "BINARY_OP_SUBSCR_FROZEN_DICT")
+        self.assert_no_opcode(binary_subscr_frozen_dict, "BINARY_OP")
+
+        def binary_subscr_frozen_dict_subclass():
+            class MyFrozenDict(frozendict):
+                pass
+            for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
+                a = MyFrozenDict({1: 2, 2: 3})
+                self.assertEqual(a[1], 2)
+                self.assertEqual(a[2], 3)
+
+        binary_subscr_frozen_dict_subclass()
+        self.assert_no_opcode(binary_subscr_frozen_dict_subclass, "BINARY_OP_SUBSCR_FROZEN_DICT")
+
         def binary_subscr_str_int():
             for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
                 a = "foobar"