kafka-testing | Test examples of kafka-clients : unit integration | Pub Sub library

I've written a basic spring boot service that consumes some data via rest API and publishes it to rabbitmq and kafka.

To test the service class handling kafka producing, I followed this guide: https://www.baeldung.com/spring-boot-kafka-testing

In isolation, the test (KafkaMessagingServiceImplTest) works perfectly both in intellij idea and via mvn on the command line. Running all project tests in idea works fine. However, when I run all project tests via maven on the command line, this test fails with an NPE when trying to make the assertion on the payload String.

I've narrowed down the location of the root problem to another test class (AppPropertiesTest) which is solely testing my AppProperties component (which is a component I use to pull config from application.properties in a tidy way). When, and only when, the tests within that test class are run alongside the failing test using 'mvn clean install' in project root, does the NPE show up. Commenting out the tests in this class or annotating it with @DirtiesContext fixes the problem. Apparently something loaded into the spring context by this test class causes an issue with the timing/order of events/countdownlatch in the other test. Of course, I don't want to use @DirtiesContext as it can lead to a much slower build as the project increases in complexity. It also does not explain the problem.. and I can't handle that :)

AppPropertiesTest uses constructor injection to inject the AppProperties component. It also extends a abstract class 'GenericServiceTest' which is annotated by: