Potential DemuxingProtocolDecoderBug

[James Talmage]

See test case for explanation

///TEST CASE BELOW

import junit.framework.TestCase;
import org.apache.mina.filter.codec.demux.MessageDecoderResult;
import org.apache.mina.filter.codec.demux.MessageDecoderAdapter;
import org.apache.mina.filter.codec.demux.DemuxingProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.core.session.DummySession;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.service.DefaultTransportMetadata;
import org.apache.mina.core.file.FileRegion;
import org.apache.mina.transport.socket.SocketSessionConfig;
import org.easymock.EasyMock;

import java.net.InetSocketAddress;
import java.nio.charset.Charset;


/**
 * Simple Unit Test showing that the DemuxingProtocolDecoder has
 * inconsistent behavior if used with a non fragmented transport.
 *
 */
public class DemuxingProtocolDecoderBugTest extends TestCase
{

    // PASSES
    public void testFragmentedTransport() throws Exception
    {
        doTest(new SessionStub(true));
    }

    // FAILS
    public void testNonFragmentedTransport() throws Exception
    {
        doTest(new SessionStub(false));
    }
    /*
        testNonFragmentedTransport() fails with the following (truncated)
stack trace:

        java.lang.AssertionError:
          Expectation failure on verify:
            write('B'): expected: 1, actual: 0
            write(1): expected: 1, actual: 0
            write(2): expected: 1, actual: 0
            write('C'): expected: 1, actual: 0
            .....
     */

    public void doTest(IoSession session) throws Exception
    {
        ProtocolDecoderOutput mock =
EasyMock.createMock(ProtocolDecoderOutput.class);
        mock.write(Character.valueOf('A'));
        mock.write(Character.valueOf('B'));
        mock.write(Integer.valueOf(1));
        mock.write(Integer.valueOf(2));
        mock.write(Character.valueOf('C'));
        EasyMock.replay(mock);

        IoBuffer buffer = IoBuffer.allocate(1000);
        buffer.putString("AB12C", Charset.defaultCharset().newEncoder());
        buffer.flip();

        DemuxingProtocolDecoder decoder = new DemuxingProtocolDecoder();
        decoder.addMessageDecoder(CharacterMessageDecoder.class);
        decoder.addMessageDecoder(IntegerMessageDecoder.class);

        decoder.decode(session,buffer,mock);

        EasyMock.verify(mock);
    }

    public static class CharacterMessageDecoder extends
MessageDecoderAdapter
    {
        public MessageDecoderResult decodable(IoSession session, IoBuffer
in)
        {
            return Character.isDigit((char)in.get())
                    ? MessageDecoderResult.NOT_OK
                    : MessageDecoderResult.OK;
        }

        public MessageDecoderResult decode(IoSession session, IoBuffer in,
ProtocolDecoderOutput out) throws Exception
        {
            out.write(Character.valueOf((char)in.get()));
            return MessageDecoderResult.OK;
        }
    }

    public static class IntegerMessageDecoder extends MessageDecoderAdapter
    {
        public MessageDecoderResult decodable(IoSession session, IoBuffer
in)
        {
            return Character.isDigit((char)in.get())
                    ? MessageDecoderResult.OK
                    : MessageDecoderResult.NOT_OK;
        }

        public MessageDecoderResult decode(IoSession session, IoBuffer in,
ProtocolDecoderOutput out) throws Exception
        {
            out.write(Integer.parseInt("" + (char)in.get()));
            return MessageDecoderResult.OK;
        }
    }

    public static class SessionStub extends DummySession
    {
        public SessionStub(boolean fragmented)
        {
            setTransportMetadata(
                new DefaultTransportMetadata(
                        "nio", "socket", false, fragmented,
                        InetSocketAddress.class,
                        SocketSessionConfig.class,
                        IoBuffer.class, FileRegion.class)
            );
        }
    }