WordCountLambdaIntegrationTest.java

/**
 * Copyright 2016 Confluent Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package io.confluent.examples.streams;

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.common.serialization.LongDeserializer;
import org.apache.kafka.common.serialization.Serde;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.KStreamBuilder;
import org.junit.BeforeClass;
import org.junit.ClassRule;
import org.junit.Test;

import java.util.Arrays;
import java.util.List;
import java.util.Properties;

import io.confluent.examples.streams.kafka.EmbeddedSingleNodeKafkaCluster;

import static org.assertj.core.api.Assertions.assertThat;

/**
 * End-to-end integration test based on {@link WordCountLambdaExample}, using an embedded Kafka
 * cluster.
 *
 * See {@link WordCountLambdaExample} for further documentation.
 *
 * See {@link WordCountScalaIntegrationTest} for the equivalent Scala example.
 *
 * Note: This example uses lambda expressions and thus works with Java 8+ only.
 */
public class WordCountLambdaIntegrationTest {

  @ClassRule
  public static final EmbeddedSingleNodeKafkaCluster CLUSTER = new EmbeddedSingleNodeKafkaCluster();

  private static final String inputTopic = "inputTopic";
  private static final String outputTopic = "outputTopic";

  @BeforeClass
  public static void startKafkaCluster() throws Exception {
    CLUSTER.createTopic(inputTopic);
    CLUSTER.createTopic(outputTopic);
  }

  @Test
  public void shouldCountWords() throws Exception {
    List<String> inputValues = Arrays.asList(
        "Hello Kafka Streams",
        "All streams lead to Kafka",
        "Join Kafka Summit"
    );
    List<KeyValue<String, Long>> expectedWordCounts = Arrays.asList(
        new KeyValue<>("hello", 1L),
        new KeyValue<>("kafka", 1L),
        new KeyValue<>("streams", 1L),
        new KeyValue<>("all", 1L),
        new KeyValue<>("streams", 2L),
        new KeyValue<>("lead", 1L),
        new KeyValue<>("to", 1L),
        new KeyValue<>("kafka", 2L),
        new KeyValue<>("join", 1L),
        new KeyValue<>("kafka", 3L),
        new KeyValue<>("summit", 1L)
    );

    //
    // Step 1: Configure and start the processor topology.
    //
    // This code is identical to what's shown in WordCountLambdaExample, with the exception of
    // the call to `purgeLocalStreamsState()`, which we need only for cleaning up previous runs of
    // this integration test.
    //
    final Serde<String> stringSerde = Serdes.String();
    final Serde<Long> longSerde = Serdes.Long();

    Properties streamsConfiguration = new Properties();
    streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-lambda-integration-test");
    streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, CLUSTER.bootstrapServers());
    streamsConfiguration.put(StreamsConfig.ZOOKEEPER_CONNECT_CONFIG, CLUSTER.zookeeperConnect());
    streamsConfiguration.put(StreamsConfig.KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
    streamsConfiguration.put(StreamsConfig.VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
    streamsConfiguration.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
    // Explicitly place the state directory under /tmp so that we can remove it via
    // `purgeLocalStreamsState` below.  Once Streams is updated to expose the effective
    // StreamsConfig configuration (so we can retrieve whatever state directory Streams came up
    // with automatically) we don't need to set this anymore and can update `purgeLocalStreamsState`
    // accordingly.
    streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, "/tmp/kafka-streams");

    // Remove any state from previous test runs
    IntegrationTestUtils.purgeLocalStreamsState(streamsConfiguration);

    KStreamBuilder builder = new KStreamBuilder();

    KStream<String, String> textLines = builder.stream(inputTopic);

    KStream<String, Long> wordCounts = textLines
        .flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+")))
        .map((key, word) -> new KeyValue<>(word, word))
        .countByKey(stringSerde, "Counts")
        .toStream();

    wordCounts.to(stringSerde, longSerde, outputTopic);

    KafkaStreams streams = new KafkaStreams(builder, streamsConfiguration);
    streams.start();

    //
    // Step 2: Produce some input data to the input topic.
    //
    Properties producerConfig = new Properties();
    producerConfig.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, CLUSTER.bootstrapServers());
    producerConfig.put(ProducerConfig.ACKS_CONFIG, "all");
    producerConfig.put(ProducerConfig.RETRIES_CONFIG, 0);
    producerConfig.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
    producerConfig.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
    IntegrationTestUtils.produceValuesSynchronously(inputTopic, inputValues, producerConfig);

    //
    // Step 3: Verify the application's output data.
    //
    Properties consumerConfig = new Properties();
    consumerConfig.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, CLUSTER.bootstrapServers());
    consumerConfig.put(ConsumerConfig.GROUP_ID_CONFIG, "wordcount-lambda-integration-test-standard-consumer");
    consumerConfig.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
    consumerConfig.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
    consumerConfig.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class);
    List<KeyValue<String, Long>> actualWordCounts = IntegrationTestUtils.waitUntilMinKeyValueRecordsReceived(consumerConfig,
        outputTopic, expectedWordCounts.size());
    streams.close();
    assertThat(actualWordCounts).containsExactlyElementsOf(expectedWordCounts);
  }

}