lenient().doCallRealMethod().when(handle).doSendFragment(any(byte[].class), anyInt(), anyInt());
        lenient().doCallRealMethod().when(handle).doReceiveFragment(any(byte[].class));
        lenient().doCallRealMethod().when(handle).close();

        // Add getMaxRecv() to return correct value
        lenient().when(handle.getMaxRecv()).thenReturn(4280);

                    buf.enc_ndr_short(msg.getOpnum());
                }

                doSendFragment(stub, off, msg.length, isDirect);
                off += n;
            }

            doReceiveFragment(stub, isDirect);
            buf.reset();
            buf.setIndex(8);
            buf.setLength(buf.dec_ndr_short());

            if (securityProvider != null) {
                securityProvider.unwrap(buf);

        @Override
        protected void doSendFragment(byte[] buf, int off, int length) throws IOException {
            // Mock implementation for testing
        }

        @Override
        protected int doReceiveFragment(byte[] buf) throws IOException {
            return doReceiveFragmentReturn;
        }

        @Override
        protected int doSendReceiveFragment(byte[] out, int off, int length, byte[] inB) throws IOException {

        final byte[] fragBytes = new byte[this.max_recv];
        final NdrBuffer fragBuf = new NdrBuffer(fragBytes, 0);
        while (!msg.isFlagSet(DCERPC_LAST_FRAG)) {
            doReceiveFragment(fragBytes);
            setupReceivedFragment(fragBuf);
            fragBuf.reset();
            msg.decode_header(fragBuf);
            final int stub_frag_len = msg.length - 24;