Class Misbehaved

Lib/test/test_io.py:901–905

        # Make sure a `.readinto` call which returns a value outside
        # (0, len(buffer)) raises.
        class Misbehaved(self.RawIOBase):
            def __init__(self, readinto_return) -> None:
                self._readinto_return = readinto_return
            def readinto(self, b):
                return self._readinto_return

        with self.assertRaises(ValueError) as cm:
            Misbehaved(2).read(1)