'Assert that when the given buffer is passed to
``Connection.recv_into``, whatever bytes are available to be received
that fit into that buffer are written into that buffer.'

def _no_length_test(self, factory):

    output_buffer = factory(5)
    (server, client) = self._loopback()
    server.send(b('xy'))
    self.assertEqual(client.recv_into(output_buffer), 2)
    self.assertEqual(output_buffer, bytearray(b('xy\x00\x00\x00')))
