BAEL-4609 - Testing Kafka and Spring Boot (#10249)

* BAEL-4437 - System Rules

* BAEL-4687 Testing Kafka and Spring Boot

* BAEL-4609 - Testing Kafka and Spring Boot

Co-authored-by: Jonathan Cook <jcook@sciops.esa.int>

spring-kafka/src/main/java/com/baeldung/kafka/embedded/KafkaConsumer.java

@@ -0,0 +1,39 @@
+package com.baeldung.kafka.embedded;
+
+import java.util.concurrent.CountDownLatch;
+
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.stereotype.Component;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Component
+public class KafkaConsumer {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(KafkaConsumer.class);
+
+    private CountDownLatch latch = new CountDownLatch(1);
+    private String payload = null;
+
+    @KafkaListener(topics = "${test.topic}")
+    public void receive(ConsumerRecord<?, ?> consumerRecord) {
+        LOGGER.info("received payload='{}'", consumerRecord.toString());
+        setPayload(consumerRecord.toString());
+        latch.countDown();
+    }
+
+    public CountDownLatch getLatch() {
+        return latch;
+    }
+
+    public String getPayload() {
+        return payload;
+    }
+
+    private void setPayload(String payload) {
+        this.payload = payload;
+    }
+
+}

spring-kafka/src/main/java/com/baeldung/kafka/embedded/KafkaProducer.java

@@ -0,0 +1,22 @@
+package com.baeldung.kafka.embedded;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.stereotype.Component;
+
+@Component
+public class KafkaProducer {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(KafkaProducer.class);
+
+    @Autowired
+    private KafkaTemplate<String, String> kafkaTemplate;
+
+    public void send(String topic, String payload) {
+        LOGGER.info("sending payload='{}' to topic='{}'", payload, topic);
+        kafkaTemplate.send(topic, payload);
+    }
+
+}

spring-kafka/src/main/java/com/baeldung/kafka/embedded/KafkaProducerConsumerApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.kafka.embedded;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+@EnableAutoConfiguration
+public class KafkaProducerConsumerApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(KafkaProducerConsumerApplication.class, args);
+    }
+
+}