Class MyBytesIO

Lib/test/test_io.py:3142–3145

        l = []
        base = self.BytesIO
        class MyBytesIO(base):
            def close(self):
                l.append(self.getvalue())
                base.close(self)
        b = MyBytesIO()
        t = self.TextIOWrapper(b, encoding="ascii")
        t.write("abc")