added test for delete action

kafka-ui-api/src/main/java/com/provectus/kafka/ui/cluster/service/ClusterService.java

@@ -207,6 +207,6 @@ public class ClusterService {
                 .map(partition -> new TopicPartition(topicName, partition))
                 .collect(Collectors.toList());
         return consumingService.loadOffsets(cluster, partitions)
-                .flatMap(offsets -> kafkaService.deleteTopicMessages(cluster, topicName, offsets)).next();
+                .flatMap(offsets -> kafkaService.deleteTopicMessages(cluster, topicName, offsets));
     }
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/cluster/service/ConsumingService.java

@@ -21,6 +21,8 @@ import org.apache.kafka.common.utils.Bytes;
 import org.springframework.stereotype.Service;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.FluxSink;
+import reactor.core.publisher.Mono;
+import reactor.core.publisher.MonoSink;
 import reactor.core.scheduler.Schedulers;
 
 import java.time.Duration;
@@ -55,9 +57,9 @@ public class ConsumingService {
 				.limitRequest(recordsLimit);
 	}
 
-	public Flux<Map<TopicPartition, Long>> loadOffsets(KafkaCluster cluster, List<TopicPartition> partitions) {
+	public Mono<Map<TopicPartition, Long>> loadOffsets(KafkaCluster cluster, List<TopicPartition> partitions) {
 		OffsetEmitter emitter = new OffsetEmitter(kafkaService, cluster, partitions);
-		return Flux.create(emitter::emit)
+		return Mono.create(emitter::emit)
 				.subscribeOn(Schedulers.boundedElastic());
 	}
 
@@ -194,10 +196,10 @@ public class ConsumingService {
 		private final KafkaCluster cluster;
 		private final List<TopicPartition> partitions;
 
-		public void emit(FluxSink<Map<TopicPartition, Long>> sink) {
+		public void emit(MonoSink<Map<TopicPartition, Long>> sink) {
 			try (KafkaConsumer<Bytes, Bytes> consumer = kafkaService.createConsumer(cluster)) {
 				Map<TopicPartition, Long> offsets = consumer.endOffsets(partitions);
-				sink.next(offsets);
+				sink.success(offsets);
 			} catch (Exception e) {
 				log.error("Error occurred while consuming records", e);
 				throw new RuntimeException(e);

kafka-ui-api/src/test/java/com/provectus/kafka/ui/AbstractBaseTest.java

@@ -1,5 +1,7 @@
 package com.provectus.kafka.ui;
 
+import com.provectus.kafka.ui.container.KafkaConnectContainer;
+import com.provectus.kafka.ui.container.SchemaRegistryContainer;
 import org.jetbrains.annotations.NotNull;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.boot.test.context.SpringBootTest;

kafka-ui-api/src/test/java/com/provectus/kafka/ui/KafkaConsumerTests.java

@@ -0,0 +1,68 @@
+package com.provectus.kafka.ui;
+
+import com.provectus.kafka.ui.model.TopicFormData;
+import com.provectus.kafka.ui.model.TopicMessage;
+import com.provectus.kafka.ui.producer.KafkaTestProducer;
+import lombok.extern.log4j.Log4j2;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.web.reactive.server.WebTestClient;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.stream.Stream;
+
+@ContextConfiguration(initializers = {AbstractBaseTest.Initializer.class})
+@Log4j2
+@AutoConfigureWebTestClient(timeout = "60000")
+public class KafkaConsumerTests extends AbstractBaseTest {
+
+    @Autowired
+    private WebTestClient webTestClient;
+
+
+    @Test
+    public void shouldDeleteRecords() {
+        var topicName = UUID.randomUUID().toString();
+        webTestClient.post()
+                .uri("/api/clusters/{clusterName}/topics", LOCAL)
+                .bodyValue(new TopicFormData()
+                        .name(topicName)
+                        .partitions(1)
+                        .replicationFactor(1)
+                        .configs(Map.of())
+                )
+                .exchange()
+                .expectStatus()
+                .isOk();
+
+        try(KafkaTestProducer<String, String> producer = KafkaTestProducer.forKafka(kafka)) {
+            Stream.of("one", "two", "three", "four")
+                    .forEach(value -> producer.send(topicName, value));
+        }
+
+        webTestClient.get()
+                .uri("/api/clusters/{clusterName}/topics/{topicName}/messages", LOCAL, topicName)
+                .exchange()
+                .expectStatus()
+                .isOk()
+                .expectBodyList(TopicMessage.class)
+                .hasSize(4);
+
+        webTestClient.delete()
+                .uri("/api/clusters/{clusterName}/topics/{topicName}/messages", LOCAL, topicName)
+                .exchange()
+                .expectStatus()
+                .isOk();
+
+        webTestClient.get()
+                .uri("/api/clusters/{clusterName}/topics/{topicName}/messages", LOCAL, topicName)
+                .exchange()
+                .expectStatus()
+                .isOk()
+                .expectBodyList(TopicMessage.class)
+                .hasSize(0);
+    }
+}

kafka-ui-api/src/test/java/com/provectus/kafka/ui/container/KafkaConnectContainer.java

@@ -1,4 +1,4 @@
-package com.provectus.kafka.ui;
+package com.provectus.kafka.ui.container;
 
 import org.testcontainers.containers.GenericContainer;
 import org.testcontainers.containers.KafkaContainer;

kafka-ui-api/src/test/java/com/provectus/kafka/ui/container/SchemaRegistryContainer.java

@@ -1,4 +1,4 @@
-package com.provectus.kafka.ui;
+package com.provectus.kafka.ui.container;
 
 import org.testcontainers.containers.GenericContainer;
 import org.testcontainers.containers.KafkaContainer;

kafka-ui-api/src/test/java/com/provectus/kafka/ui/producer/KafkaTestProducer.java

@@ -0,0 +1,35 @@
+package com.provectus.kafka.ui.producer;
+
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.testcontainers.containers.KafkaContainer;
+
+import java.util.Map;
+
+public class KafkaTestProducer<KeyT, ValueT> implements AutoCloseable {
+    private final KafkaProducer<KeyT, ValueT> producer;
+
+    private KafkaTestProducer(KafkaProducer<KeyT, ValueT> producer) {
+        this.producer = producer;
+    }
+
+    public static KafkaTestProducer<String, String> forKafka(KafkaContainer kafkaContainer) {
+        return new KafkaTestProducer<>(new KafkaProducer<>(Map.of(
+                ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaContainer.getBootstrapServers(),
+                ProducerConfig.CLIENT_ID_CONFIG, "KafkaTestProducer",
+                ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class,
+                ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class
+        )));
+    }
+
+    public void send(String topic, ValueT value) {
+        producer.send(new ProducerRecord<>(topic, value));
+    }
+
+    @Override
+    public void close() {
+        producer.close();
+    }
+}