Improve MockProducerFactory usability by wrapping MockProducer with …

[pszymczyk]

…CloseSafeMockProducer

Hi

In the current project, I've opted to use the MockProducer class and Spring support in the form of MockProducerFactory. Unfortunately, it turns out that after the first message is sent, KafkaTemplate by default closes the provided MockProducer instance, making it impossible to send another message. I suggest a solution in which the factory wraps the MockProducer in a class that ignores the producer's closing.

Best regards,
Pawel

[sobychacko]

@pszymczyk Checkstyle failures in the PR build. Could you fix them? https://github.com/spring-projects/spring-kafka/actions/runs/7251864605/job/19755109702?pr=2961

[sobychacko]

Build is still failing.

[pszymczyk]

I've executed ./gradlew idea and then executed reformat from Intellij Idea and it's still failing, to be honest I don't know how to fix it.

[sobychacko]

Can you see the output on this build here? https://github.com/spring-projects/spring-kafka/actions/runs/7252844586/job/19758171575

[pszymczyk]

I see:

 Error: [Task :spring-kafka:checkstyleMain] [ImportOrder] Wrong order for 'java.time.Duration' import.
Error: [Task :spring-kafka:checkstyleMain] [RegexpSinglelineJava] Line has leading space characters; indentation should be performed with tabs only.

[pszymczyk]

Sorry but I have no idea what is wrong with following imports order:

import java.time.Duration;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Future;
import java.util.function.BiFunction;
import java.util.function.Supplier;

[sobychacko]

@pszymczyk As a solution to this problem, in your test, you can extend the MockProducer and override the close method. Then provide an instance of this implementation to the MockProducerFactory supplier. Did you try that option?

Discussed this with @artembilan. KafkaTemplate is not the right component to make these decisions about whether the producer needs to be closed or not. It should be the producer's responsibility to do that, and the solution we suggested above does that. Therefore, we suggest using this approach in your testing scenario.

We will update the testing chapter in the reference docs with these details.