How to unit test Spring IntegrationFlow?

Question

I have been using Spring Integration DSL to implement some messaging processing flow.

How can I actually unit test a single IntegrationFlow, can anyone provide me with an example on how to unit test i.e. transform part of this bean:

@Bean public IntegrationFlow transformMessage(){ return message -> message .transform(new GenericTransformer<Message<String>, Message<String>>() { @Override public Message<String> transform(Message<String> message) { MutableMessageHeaders headers = new MutableMessageHeaders(message.getHeaders()); headers.put("Content-Type", "application/json"); headers.put("Accept", "application/json"); String payload = "Long message"; ObjectMapper mapper = new ObjectMapper(); HashMap<String, String> map = new HashMap<>(); map.put("payload", payload); String jsonString = null; try { jsonInString = mapper.writeValueAsString(map); } catch (JsonProcessingException e) { logger.error("Error:" + e.getMessage()); } Message<String> request = new GenericMessage<String>(jsonString , headers); return request; } }) .handle(makeHttpRequestToValidateAcdrMessage()) .enrichHeaders(h -> h.header("someHeader", "blah", true)) .channel("entrypoint"); }

How can I test it?

Regards!

Artem Bilan · Accepted Answer · 2017-02-02 17:30:19Z

Seems for me "unit testing" means check the behavior of the particular part of the system, some small component.

So, in your case it is about that new GenericTransformer.

so, just make it as a top-level component and perform tests against its isolated instances!

The integration tests can be performed against the target IntegrationFlow as well.

Each EIP-component in the flow definition is surrounded with MessageChannels - input and output. Even if you don't declare .channel() there, the Framework build implicit DirrectChannel to wire endpoints to the flow.

Those implicit get the bean name like:

channelBeanName = flowNamePrefix + "channel" + BeanFactoryUtils.GENERATED_BEAN_NAME_SEPARATOR + channelNameIndex++;

So, since your IntegrationFlow is from Lambda, the input channel form the .transform() is just input of the flow - transformMessage.input.

The channel between .transform() and the next .handle() has bean name like: transformMessage.channel#0, because it will be a first implicit channel declaration.

The idea that you can @Autowired both of this channels to your test-case and add ChannelInterceptor to them before testing.

The ChannelInterceptor may play verificator role to be sure that you send to the transformer and receive from the a proper data as it is expected.

More info can be found here: https://github.com/spring-projects/spring-integration-java-dsl/issues/23

Gary Russell · Accepted Answer · 2017-02-02 17:30:30Z

The same techniques described in the testing-samples project in the samples repo can be used here.

The send a message to channel transform.input and subscribe to entrypoint to get the result (or change it to a QueueChannel in your test case.

Rakesh · Accepted Answer · 2017-12-18 12:13:41Z

1

Example of DSL IntegrationFlows testing is on github.

answered Dec 18, 2017 at 12:13

Rakesh

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