Overridden onMessage of MessageListner not getting called in Spring Kafka Consumer Unit Test - spring-boot

Question

I am writing Kafka Consumer Unit Test, and need to Mock the Service of my KafkaConsumer for testing the Kafka Consumer independently. But, the mockObject of Service is not getting invoked, instead Spring is creating the original Service class object and calling it. Thus, my mock class object not getting called.
KafkaConsumer :
#Slf4j
#Component
#RequiredArgsConstructor (onConstructor = #__(#Autowired))
public class KafkaEventConsumer {
private final MyService requestService;
#KafkaListener (topics = "${kafka.topic:topic-name}")
public void receive(#Payload String message) throws Exception {
try {
LOGGER.debug("Received message:{} ", message);
ObjectMapper mapper = new ObjectMapper();
ForecastRequest forecastRequest = mapper.readValue(message, ForecastRequest.class);
JobDetail jobDetail = requestForecastService.refreshForecasts(forecastRequest);
if (jobDetail.getJobStatus() != JobStatus.complete) {
LOGGER.error("Failed to Refresh Forecast for ProgramId-{}, JobId-{}, JobStatus-{}",
forecastRequest.getProgramId(), jobDetail.getJobId(), jobDetail.getJobStatus());
throw new Exception("Internal Server Error");
}
} catch (Exception e) {
LOGGER.error("Failed to Refresh Forecast for Forecast Request {}", message, e);
throw e;
}
}
}
Kafka Consumer Test :
#RunWith (SpringRunner.class)
#ActiveProfiles ("kafkatest")
#SpringBootTest (classes = ForecastEventConsumerApplication.class)
#DirtiesContext
public class KafkaEventConsumerTest {
private static String TOPIC = "topic-name";
#Mock
private MyServiceImpl myServiceMock;
#InjectMocks
private KafkaEventConsumer kafkaEventConsumer;
private KafkaTemplate<String, String> template;
#Autowired
private KafkaListenerEndpointRegistry kafkaListenerEndpointRegistry;
#ClassRule
public static final KafkaEmbedded embeddedKafka = new KafkaEmbedded(1, true,3, TOPIC);
#Before
public void setUp() throws Exception {
kafkaEventConsumer = new KafkaEventConsumer(myServiceMock);
// set up the Kafka producer properties
Map<String, Object> senderProperties = KafkaTestUtils.senderProps(embeddedKafka.getBrokersAsString());
// create a Kafka producer factory
ProducerFactory<String, String> producerFactory = new DefaultKafkaProducerFactory<String, String>(senderProperties);
// create a Kafka template
template = new KafkaTemplate<>(producerFactory);
// set the default topic to send to
template.setDefaultTopic(TOPIC);
// wait until the partitions are assigned
for (MessageListenerContainer messageListenerContainer : kafkaListenerEndpointRegistry.getListenerContainers()) {
messageListenerContainer.setupMessageListener(new MessageListener<String, String>() {
#Override
public void onMessage(ConsumerRecord<String, String> record) {
try {
kafkaEventConsumer.receive(record.value());
} catch (Exception e) {
e.printStackTrace();
}
}
});
ContainerTestUtils.waitForAssignment(messageListenerContainer, embeddedKafka.getPartitionsPerTopic());
}
}
#AfterClass
public static void tearDown() throws Exception {
embeddedKafka.destroy();
}
#Test
public void testReceive() throws Exception {
String forecastRequestMessage = "{\"programId\":100011770}";
ForecastRequest forecastRequest = ForecastRequest.builder().programId(100011770L).build();
JobDetail jobDetail = JobDetail.builder().jobStatus(JobStatus.complete).build();
Mockito.when(forecastServiceMock.refreshForecasts(Matchers.any())).thenReturn(jobDetail);
template.sendDefault(forecastRequestMessage);
Thread.sleep(2000L);
// validate something
}
}
The problem is, in the above #Test method instead of calling the mocked version of MyService it is calling the original MyService implementation. Also, while debugging my code I found that overridden onMessage() is also not getting called. Please help me in finding what am I doing wrong here.

Answer 1

You have to stop() all the MessageListenerContainers before calling their setupMessageListener(). Then you will need to start() them back to let them to pick up a fresh listener:
protected void doStart() {
...
Object messageListener = containerProperties.getMessageListener();
Assert.state(messageListener != null, "A MessageListener is required");
Anyway that sounds like you really would like to mock only your MyService which is injected into the real KafkaEventConsumer. So, how about to consider to use that like this:
#MockBean
private MyServiceImpl myServiceMock;
And you won't need to do anything in your #Before and no need in the #InjectMocks.
The KafkaEmbedded can expose its host/port (or brokers) properties to the expected Spring Boot conventional configuration properties like this:
#BeforeClass
public static void setup() {
System.setProperty("spring.kafka.bootstrap-servers", kafkaEmbedded.getBrokersAsString());
}
https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#boot-features-testing-spring-boot-applications-mocking-beans