def test_short_header_max_flight_bytes_zero(self):
        """
        max_flight_bytes = 0 only allows ACKs and CONNECTION_CLOSE.

        Check CRYPTO is not allowed.
        """
        builder = create_builder()
        builder.max_flight_bytes = 0

        crypto = create_crypto()

        with self.assertRaises(QuicPacketBuilderStop):
            builder.start_packet(QuicPacketType.ONE_RTT, crypto)
            builder.start_frame(QuicFrameType.CRYPTO)

        # check datagrams
        datagrams, packets = builder.flush()
        self.assertEqual(len(datagrams), 0)

        # check builder
        self.assertEqual(builder.packet_number, 0)

        max_flight_bytes = 0 only allows ACKs and CONNECTION_CLOSE.

        Check CRYPTO is not allowed.
        
tests/test_packet_builder.py