Kafka JUnit

Kafka Junit provides helpers for starting and tearing down a Kafka broker during tests.

Please note that version 3.x.x drops Java 7 support and contains 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.

Javadocs

http://charithe.github.io/kafka-junit/

Usage

JUnit 4

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(EphemeralKafkaBroker.create());

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(EphemeralKafkaBroker.create());

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

@Test
public void testSomething(){
    // Convenience methods to produce and consume messages
    kafkaRule.helper().produceStrings("my-test-topic", "a", "b", "c", "d", "e");
    List<String> result = kafkaRule.helper().consumeStrings("my-test-topic", 5).get();

    // or use the built-in producers and consumers
    KafkaProducer<String, String> producer = kafkaRule.helper().createStringProducer();

    KafkaConsumer<String, String> consumer = kafkaRule.helper().createStringConsumer();

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

EphemeralKafkaBroker contains the core logic used by the JUnit rule and can be used independently.

KafkaHelper contains a bunch of convenience methods to work with the EphemeralKafkaBroker

JUnit 5

JUnit 5 does not have support for Rules, but instead uses the new JUnit 5 Extension Model.

So if you are using JUnit 5 you can use KafkaJunitExtension which provides a kafka broker that is started and stopped for each test.

The extension is configured using the optional class annotation @KafkaJunitExtensionConfig and provides dependency injection for constructors and methods for the classes KafkaHelper and EphemeralKafkaBroker

@ExtendWith(KafkaJunitExtension.class)
@KafkaJunitExtensionConfig(startupMode = StartupMode.WAIT_FOR_STARTUP)
class MyTestClass {

    @Test
    void testSomething(KafkaHelper kafkaHelper) throws ExecutionException, InterruptedException {
        // Convenience methods to produce and consume messages
        kafkaHelper.produceStrings("my-test-topic", "a", "b", "c", "d", "e");
        List<String> result = kafkaHelper.consumeStrings("my-test-topic", 5).get();
        assertThat(result).containsExactlyInAnyOrder("a", "b", "c", "d", "e");

        // or use the built-in producers and consumers
        KafkaProducer<String, String> producer = kafkaHelper.createStringProducer();

        KafkaConsumer<String, String> consumer = kafkaHelper.createStringConsumer();

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

Refer to Javadocs and unit tests for more usage examples.