I am new to spring integration. I need to write unit test for the integeration graph. This graph starts with gateway->splitter->enricher->aggregator->Transformer. So if i want to write a unit test for enricher alone, how do i need to do it.?
I referred this article, but all of them has only one component. But how to do it in this case as above.?
It's not clear why the testing samples referenced by your cited answer don't help you. It doesn't matter what's in the flow; the basic idea is to send a message into the start of the flow and examine the result from the end of the flow, perhaps by replacing the final channel with a queue channel, which you can poll from your test case.
You can stop() the ultimate consumer so he doesn't grab the result.
EDIT: (in response to comments below).
You can preempt the component's output channel...
... <int:channel id="toHE"/> <int:header-enricher id="he" input-channel="toHE" output-channel="fromHE"> <int:header name="foo" value="bar"/> </int:header-enricher> <int:channel id="fromHE"/> ... And then...
@Autowired private MessageChannel toHE; @Autowired @Qualifier("he.handler") private MessageTransformingHandler headerEnricher; @Test @DirtiesContext public void testEnricher() { PollableChannel outputChannel = new QueueChannel(); headerEnricher.setOutputChannel(outputChannel); toHE.send(MessageBuilder.withPayload("baz").build()); Message<?> out = outputChannel.receive(10000); assertNotNull(out); assertEquals("bar", out.getHeaders().get("foo")); } 
