Method check

Lib/test/test_pickle.py:230–240

(Pickler)

    @support.cpython_only
    def test_pickler_reference_cycle(self):
        def check(Pickler):
            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
                f = io.BytesIO()
                pickler = Pickler(f, proto)
                pickler.dump('abc')
                self.assertEqual(self.loads(f.getvalue()), 'abc')
            pickler = Pickler(io.BytesIO())
            self.assertEqual(pickler.persistent_id('def'), 'def')
            r = weakref.ref(pickler)
            del pickler
            self.assertIsNone(r())

        class PersPickler(self.pickler):
            def persistent_id(subself, obj):