John Sandfort February 2016

How can I force a RabbitMQ broker to NACK a message for testing?

I'm working on a Spring Boot project using RabbitMQ via Spring AMQP. We'd like to be able to test our app's behavior when a message publish is NACK'd (specifically when the ack argument of PublisherConfirmCallback#confirm is false). However we're having a hard time trying to set up this scenario in an integration test (that is, with the app running, not a unit test).

Just to be clear, we're testing around publisher acknowledgements, not consumer acknowledgements.

We know you can get access to a channel with the RabbitTemplate's execute method, but our RabbitMQ auto-acks, so the message is already gone by the time the channel callback is executed. We're thinking we might be able to either disable auto-ack at runtime (so as not to interrupt the test suite) or to simply block the channel and receive the message on it manually in the test, but we can't figure out how to do either of these. But really, any way to cause a NACK during a test would be great.

tl;dr how to nack a message from client code

Answers


Derick Bailey February 2016

you will have to turn off auto-ack, to start with. with that turned on, it will not be possible to nack a message.

after that, you're test setup should include a message consumer that is coded specifically to do what you want, when you want... don't use your real code to test the nack handling. set up a consumer that only does a nack... or one that knows when it receives certain messages, it should nack


John Sandfort February 2016

Publishing a message to a nonexistent exchange will cause the publisher confirm callback to receive a nack!

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Asked in February 2016
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