Testing Kafka consumer #KafkaListener with EmbeddedKafka in Spring Boot - spring-boot

Question

I want to test my kafka consumer, but there is in issue with #EmbddedKafka.
#Slf4j
#Component
#RequiredArgsConstructor
public class KafkaEventConsumer {
private final CustomInterface customInterface;
#KafkaListener(topics = "test-topic")
public void consumeEvents(Event event) {
customInterface.apply(event);
}
}
}
My test class is as the following
#EmbeddedKafka
#ExtendWith(MockitoExtension.class)
#SpringBootTest(properties = "spring.kafka.bootstrap-servers=${spring.embedded.kafka.brokers}")
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
class KafkaConsumerTest {
private Producer<String, String> producer;
private static File EVENT_JSON = Paths.get("src", "test", "resources", "files",
"event-file.json").toFile();
private KafkaEventConsumer kafkaEventConsumer;
#Mock
private CustomInterface CustomInterface;
#Autowired
private EmbeddedKafkaBroker embeddedKafkaBroker;
#Autowired
private ObjectMapper objectMapper;
#BeforeAll
void setUp() {
kafkaEventConsumer = new KafkaEventConsumer(customInterface);
Map<String, Object> configs = new HashMap<>(KafkaTestUtils.producerProps(embeddedKafkaBroker));
producer = new DefaultKafkaProducerFactory<>(configs, new StringSerializer(),
new StringSerializer()).createProducer();
}
#Test
void consumeEvents() throws IOException, BadCurrencyException {
var event = objectMapper.readValue(EVENT_JSON,Event.class);
String message = objectMapper.writeValueAsString(event);
producer.send(new ProducerRecord<>("test-topic", 0, "1", message));
producer.flush();
// Read the message and assert its properties
verify(customeInterface, timeout(10000).times(1)).apply(any());
}
#AfterAll
void shutdown() {
producer.close();
}
}
The test doesn't pass, the consumer didn't intercept the message
Wanted but not invoked:
customInterface.apply(
<any> );
Actually, there were zero interactions with this mock.
PS: I followed this interesting article

Answer 1

I used KafkaTemplate
#SpringBootTest
#EmbeddedKafka(brokerProperties = {"listeners=PLAINTEXT://localhost:9092"},
partitions = 1,
controlledShutdown = true)
class KafkaConsumerTest {
private static File EVENT_JSON = Paths.get("src", "test", "resources", "files",
"event-file.json").toFile();
#Autowired
KafkaTemplate<String, Event> kafkaTemplate;
#Autowired
private ObjectMapper objectMapper;
#SpyBean
private KafkaEvenConsumer kafkaEvenConsumer;
#SpyBean
private CustomInterface customInterface;
#Captor
ArgumentCaptor<Event> eventCaptor;
#Test
#SneakyThrows
#DirtiesContext
void consumeEvents() {
Event event = objectMapper.readValue(EVENT_JSON, Event.class);
kafkaTemplate.send("test-topic, "1", event);
verify(kafkaEventConsumer,timeout(10000).times(1)).consumeEvents(eventCaptor.capture());
Event argument = eventCaptor.getValue();
// .. assert the message properties
verify(customInterface, timeout(10000).times(1)).apply(any());
}
}