I'm working on a SpringBoot application that must process messages sent via Kafka. In the application, I have a Spring Bean with methods annotated with @KafkaListener. These methods get called when a message is read from the appropriate topic and call a business logic to perform actual processing.
Now I'd like to create a test for this using the lib "spring-kafka-test", i.e. embedded kafka. I've created a test that sends a message to the topic and then checks whether the business logic has been called. The logic is mocked via @MockBean.
My test class looks like this:
@SpringBootTest
@DirtiesContext
@EmbeddedKafka(
topics = { "myTopic" },
brokerProperties = { "listeners=PLAINTEXT://localhost:9092" } // <-- Why is this needed?
)
class KafkaListenerDispatchingTest {
/** Object for sending the test messages */
@Autowired
private KafkaTemplate<String, String> kafkaTemplate;
@MockBean
private BusinessLogic businessLogic;
@Test
public void testProcessing() throws Exception {
var testMessage = "...";
kafkaTemplate.send("myTopic", testMessage).get();
Mockito.verify(businessLogic).myMethod();
}
}
Without the line marked with "Why is this needed" the test does not work. In the console I see many lines with
[Producer clientId=producer-1] Connection to node -1 (localhost/127.0.0.1:9092) could not be established. Broker may not be available.
With the marked line the test works OK.
My question is: Why is the broker property listeners needed? From the Spring class (EmbeddedKafka) I'd expect that everything works with the default values and that special values only must be specified when having special needs.
I have
- spring-boot 2.7.13
- spring-kafka 2.9.9
- spring-kafka-test 2.9.9
