Kafka JUnit Rule

JUnit rule for starting and tearing down a Kafka broker during tests.

Version	Kafka Version
1.6	0.8.2.1
1.7	0.8.2.2
1.8	0.9.0.0
2.0	0.9.0.1

Please note that version 2.0 is for Java 1.8 and up and contains some breaking API changes.

Installation

Releases are available on Maven Central.

Snapshot versions containing builds from the latest master are available in the Sonatype snapshots repo.

Usage

Create an instance of the rule in your test class and annotate it with @Rule. This will start and stop the broker between each test invocation.

@Rule
public KafkaJunitRule kafkaRule = new KafkaJunitRule();

To spin up the broker at the beginning of a test suite and tear it down at the end, use @ClassRule.

@ClassRule
public static KafkaJunitRule kafkaRule = new KafkaJunitRule();

kafkaRule can be referenced from within your test methods to obtain information about the Kafka broker.

@Test
public void testSomething(){
    // Use the built-in producer
    KafkaProducer<String, String> producer = kafkaRule.createStringProducer();

    // Use the built-in consumer 
    KafkaConsumer<String, String> consumer = kafkaRule.createStringConsumer();

    // Alternatively, the Zookeeper connection String and the broker port can be retrieved to generate your own config
    String zkConnStr = kafkaRule.zookeeperConnectionString();
    int brokerPort = kafkaRule.kafkaBrokerPort();

    ...
}

There are also helper methods available to read a number of messages with a configurable timeout.

@Test
public void testMessagesCanBeRead() throws TimeoutException {
    // write a message 
    try (KafkaProducer<String, String> producer = kafkaRule.createStringProducer()) {
        producer.send(new ProducerRecord<>(TOPIC, KEY, VALUE));
    }

    // attempt to read a single message with a 5 second timeout
    List<String> messages = kafkaRule.readStringMessages(TOPIC, 1, 5);
    assertThat(messages, is(notNullValue()));
    assertThat(messages.size(), is(1));

    String msg = messages.get(0);
    assertThat(msg, is(notNullValue()));
    assertThat(msg, is(equalTo(VALUE)));
}

Refer to unit tests for more examples.