netty using EmbeddedChannel of inbound and outbound channel unit test

A special Channel realize ---- EmbeddedChannel, it is designed for improved Netty unit tests for the ChannelHandler provided.

name	Responsibility
writeInbound	Inbound message written in EmbeddedChannel. If the data can be read from EmbeddedChannel by readInbound method Returns true
readInbound	EmbeddedChannel read from the inbound message. Any return everything through the entire ChannelPipeline. If you do not read any available, null is returned
writeOutbound	EmbeddedChannel outbound message is written, if something can now read from EmbeddedChannel by readOutbound, return true
readOutbound	EmbeddedChannel read from the outbound message. Any return everything through the entire ChannelPipeline. If you do not read any available, null is returned
finish	The EmbeddedChannel marked complete if the inbound or outbound data can be read, it returns true. This method will also call the close method on the EmbeddedChannel

Test inbound message

public class FixedLengthFrameDecoder extends ByteToMessageDecoder {
    private final int frameLength;

    public FixedLengthFrameDecoder(int frameLength) {
        if (frameLength <= 0) {
            throw new IllegalArgumentException("frameLength must be positive integer: " + frameLength);
        }
        this.frameLength = frameLength;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        while (in.readableBytes() >= frameLength) {
            ByteBuf buf = in.readBytes(frameLength);
            out.add(buf);
        }
    }
}

public class FixedLengthFrameDecoderTest {
    @Test
    public void testFramesDecoded() {
        ByteBuf buf = Unpooled.buffer();
        for (int i = 0; i < 9; i++) {
            buf.writeByte(i);
        }
        ByteBuf input = buf.duplicate();
        EmbeddedChannel channel = new EmbeddedChannel(new FixedLengthFrameDecoder(3));
        Assert.assertTrue(channel.writeInbound(input.retain()));
        Assert.assertTrue(channel.finish());

        ByteBuf read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        Assert.assertNull(channel.readInbound());
        buf.release();
    }

    @Test
    public void testFramesDecoded2() {
        ByteBuf buf = Unpooled.buffer();
        for (int i = 0; i < 9; i++) {
            buf.writeByte(i);
        }
        ByteBuf input = buf.duplicate();
        EmbeddedChannel channel = new EmbeddedChannel(new FixedLengthFrameDecoder(3));
        Assert.assertFalse(channel.writeInbound(input.readBytes(2)));
        Assert.assertTrue(channel.writeInbound(input.readBytes(7)));
        Assert.assertTrue(channel.finish());
        ByteBuf read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(3), read);
        read.release();

        Assert.assertNull(channel.readInbound());
        buf.release();
    }
}

Test outbound messages

public class AbsIntegerEncoder extends MessageToMessageEncoder<ByteBuf> {
    @Override
    protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf in, List<Object> out) throws Exception {
        while (in.readableBytes() >= 4) {
            int value = Math.abs(in.readInt());
            out.add(value);
        }
    }
}

public class AbsIntegerEncoderTest {
    @Test
    public void testEncoded() {
        ByteBuf buf = Unpooled.buffer();
        for (int i = 0; i < 10; i++) {
            buf.writeInt(i * -1);
        }
        EmbeddedChannel channel = new EmbeddedChannel(new AbsIntegerEncoder());
        Assert.assertTrue(channel.writeOutbound(buf));
        Assert.assertTrue(channel.finish());

        for (int i = 0; i < 10; i++) {
            Assert.assertEquals(Integer.valueOf(i), channel.readOutbound());
        }
        Assert.assertNull(channel.readOutbound());
    }
}

Test Exception Handling

public class FrameChunkDecoder extends ByteToMessageDecoder {
    private final int maxFrameSize;

    public FrameChunkDecoder(int maxFrameSize) {
        this.maxFrameSize = maxFrameSize;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        int readableBytes = in.readableBytes();
        if (readableBytes > maxFrameSize) {
            in.clear();
            throw new TooLongFrameException();
        }
        ByteBuf buf = in.readBytes(readableBytes);
        out.add(buf);
    }
}

public class FrameChunkDecoderTest {
    @Test
    public void testFramesDecoded() {
        ByteBuf buf = Unpooled.buffer();
        for (int i = 0; i < 9; i++) {
            buf.writeByte(i);
        }
        ByteBuf input = buf.duplicate();
        EmbeddedChannel channel = new EmbeddedChannel(new FrameChunkDecoder(3));
        Assert.assertTrue(channel.writeInbound(input.readBytes(2)));
        try {
            channel.writeInbound(input.readBytes(4));
            Assert.fail();
        } catch (TooLongFrameException e) {

        }
        Assert.assertTrue(channel.writeInbound(input.readBytes(3)));
        Assert.assertTrue(channel.finish());

        ByteBuf read = channel.readInbound();
        Assert.assertEquals(buf.readSlice(2), read);
        read.release();

        read = channel.readInbound();
        Assert.assertEquals(buf.skipBytes(4).readSlice(3), read);
        read.release();
        buf.release();
    }
}