byte[] data = new byte[] { 1, 2, 3 };
        byte[] fullData = concat(messageHeader(3), data);
        InputStream in = new ByteArrayInputStream(fullData);
        SocketInputStream sis = new SocketInputStream(in);

        // Read the three data bytes
        assertEquals(1, sis.read());
        assertEquals(2, sis.read());
        assertEquals(3, sis.read());