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.

Version support matrix

Version	Kafka Version
1.6	0.8.2.1
1.7	0.8.2.2
1.8	0.9.0.0
2.3	0.9.0.1
2.4	0.10.0.0
2.5	0.10.0.1
3.0.0	0.10.0.1
3.0.1	0.10.0.1
3.0.2	0.10.1.1
3.0.3	0.10.2.0
3.0.4	0.10.2.1
3.1.0	0.11.0.0
3.1.1	0.11.0.1
4.0.0	1.0.0
4.1.0	1.0.0 (Adds support for both Junit 4 and 5)
4.1.1	1.1.0
4.1.2	2.0.0
4.1.3	2.1.0
4.1.4	2.1.1
4.1.5	2.2.0
4.1.6	2.3.0
4.1.7	2.4.0
4.1.8	2.4.1
4.1.9	2.5.0
4.1.10	2.6.0
4.1.11	2.6.0 (Scala 2.13)
4.2.0	2.8.0

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.