Unit testing
This chapter covers
- Unit testing
- Overview of
EmbeddedChannel - Testing
ChannelHandlerswithEmbeddedChannel
Overview of EmbeddedChannel
Netty provides what it calls an embedded transport for testing ChannelHandlers. This transport is a feature of a special Channel implementation, EmbeddedChannel, which provides a simple way to pass events through the pipeline.
The relevant methods of EmbeddedChannel are listed in the following table.
Figure 9.1 shows how data flows through the ChannelPipeline using the methods of EmbeddedChannel.
Testing ChannelHandlers with EmbeddedChannel
Testing inbound messages
Figure 9.2 represents a simple ByteToMessageDecoder implementation.
The implementation of the decoder is shown in the following listing.
This listing shows a test of the preceding code using EmbeddedChannel.
Testing outbound messages
Figure 9.3 shows the logic.
The next listing implements this logic, illustrated in figure 9.3.
The next listing tests the code using EmbeddedChannel.
Testing exception handling
In figure 9.4 the maximum frame size has been set to 3 bytes. If the size of a frame exceeds that limit, its bytes are discarded and a TooLongFrameException is thrown.
The implementation is shown in the following listing.
Again, we’ll test the code using EmbeddedChannel.
The try/catch block used here is a special feature of EmbeddedChannel. If one of the write* methods produces a checked Exception, it will be thrown wrapped in a RuntimeException.