如何使用Kafka DSL进行Spring Cloud Stream单元测试

Question

我正在尝试（单元）测试使用Kafka DSL的Spring Cloud Stream Kafka处理器，但收到以下错误“ Connection to node -1 could not be established. Broker may not be available.”。此外，测试不会关闭。我同时尝试了EmbeddedKafka和TestBinder，但是我有相同的行为。我尝试从Spring Cloud Team（有效）给出的响应开始，我将应用程序改编为使用Kafka DSL，并几乎保持了测试类。EmbeddedKafka是否实际上支持Kafka DSL？

我正在使用Elmhurst.RELEASE

@SpringBootApplication
@EnableBinding(MyBinding.class)
public class So43330544Application {

    public static void main(String[] args) {
        SpringApplication.run(So43330544Application.class, args);
    }

    @StreamListener
    @SendTo(MyBinding.OUTPUT)
    public KStream<String,String> process(@Input(MyBinding.INPUT) KStream<String, String> in) {

        return in.peek((k,v) -> System.out.println("Received value " +v ))
                .mapValues(v -> v.toUpperCase());
    }
}

interface MyBinding {

    String INPUT = "input";
    String OUTPUT = "output";

    @Input(INPUT)
    KStream<String, String> messagesIn();

    @Output(OUTPUT)
    KStream<String, String> messagesOut();
} 

---

更新资料

如下例所示，当我使用Spring Cloud Stream通用语法编写事件处理器时，此答案中提出的方法对我有效，但当我使用Kafka DSL（KStreams）时不起作用。要查看行为上的差异，只需切换到ExampleAppWorking或ExampleAppNotWorking在@SpringBootTest注释中：

@RunWith(SpringRunner.class)
@SpringBootTest(classes=ExampleKafkaEmbeddedTest.ExampleAppNotWorking.class)
@DirtiesContext(classMode=ClassMode.AFTER_EACH_TEST_METHOD)
public class ExampleKafkaEmbeddedTest {
    @ClassRule
    public static KafkaEmbedded embeddedKafka = new KafkaEmbedded(1, false, "so0544in","so0544out");

    @Autowired
    private KafkaTemplate<Integer, byte[]> template;

    @Autowired
    private KafkaProperties properties;

    private static Consumer consumer;

    @BeforeClass
    public static void setup() throws Exception{
        System.setProperty("spring.kafka.bootstrap-servers", embeddedKafka.getBrokersAsString());
        System.setProperty("spring.cloud.stream.kafka.binder.zkNodes", embeddedKafka.getZookeeperConnectionString());
        System.setProperty("server.port","0");
        System.setProperty("spring.jmx.enabled" , "false");

        Map<String, Object> consumerProps = KafkaTestUtils.consumerProps("group-id", "false", embeddedKafka);

        consumerProps.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        consumerProps.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        consumerProps.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
        DefaultKafkaConsumerFactory<String, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
        consumer = cf.createConsumer();
        embeddedKafka.consumeFromAnEmbeddedTopic(consumer, "so0544out");

    }

    @After
    public void tearDown() {
        if (consumer != null){
            consumer.close();
        }
    }

    @Test
    public void testSendReceive() {
        template.send("so0544in", "foo".getBytes());

        Map<String, Object> configs = properties.buildConsumerProperties();
        configs.put(ConsumerConfig.GROUP_ID_CONFIG, "test0544");
        configs.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");

        ConsumerRecord<String, String> cr = KafkaTestUtils.getSingleRecord(consumer, "so0544out");

        System.out.println("Contenu chaine resultat : " + cr.value());

        assertEquals(cr.value(), "FOO");
    }

    @SpringBootApplication
    @EnableBinding(Processor.class)
    public static class ExampleAppWorking {

        public static void main(String[] args) {
            SpringApplication.run(ExampleAppWorking.class, args);
        }

        @StreamListener(Processor.INPUT)
        @SendTo(Processor.OUTPUT)
        public String receive(String in) {
            return in.toUpperCase();
        }
    }

    @SpringBootApplication
    @EnableBinding(MyBinding.class)
    public static class ExampleAppNotWorking {

        public static void main(String[] args) {
            SpringApplication.run(ExampleAppNotWorking.class, args);
        }

        @StreamListener
        @SendTo(MyBinding.OUTPUT)
        public KStream<Integer,byte[]> toUpperCase (@Input(MyBinding.INPUT) KStream<Integer,byte[]> in){
            return in.map((key, val) -> KeyValue.pair(key, new String(val).toUpperCase().getBytes()));
        }
    }

    public interface MyBinding {
        String INPUT = "input";
        String OUTPUT = "output";

        @Input(INPUT)
        KStream<Integer, String> messagesIn();

        @Input(OUTPUT)
        KStream<Integer, String> messagesOut();
    }

}

Answer 1

EmbeddedKafa应该与Kafka Streams一起使用。所有这些测试都使用EmbeddedKafa进行测试。您可以遵循这些测试中使用的模式作为自己测试的模板。

查看了您在下面的注释中提供的代码。您需要在您的setup方法中添加此属性。

System.setProperty("spring.cloud.stream.kafka.streams.binder.brokers", embeddedKafka.getBrokersAsString());

Spring Boot的主要应用程序期望Kafka代理在本地主机上可用，并且不知道该测试正在运行嵌入式代理。我们需要通过在测试中设置该属性来使事实明确，以便主启动应用程序正确检测嵌入式kafka代理。