Verbesserte Tests und Korrekturen gemerged: sumup-adder -> stored-offsets stored-offsets
authorKai Moritz <kai@juplo.de>
Sun, 14 Aug 2022 18:52:49 +0000 (20:52 +0200)
committerKai Moritz <kai@juplo.de>
Sun, 14 Aug 2022 18:56:09 +0000 (20:56 +0200)
1  2 
README.sh
pom.xml
src/main/java/de/juplo/kafka/ApplicationRebalanceListener.java
src/test/java/de/juplo/kafka/ApplicationTests.java
src/test/java/de/juplo/kafka/GenericApplicationTests.java

diff --cc README.sh
+++ b/README.sh
@@@ -16,7 -16,8 +16,8 @@@ if [
    "$1" = "build"
  ]]
  then
-   mvn install || exit
 -  docker-compose rm -svf adder
++  docker-compose rm -svf peter beate
+   mvn clean install || exit
  else
    echo "Using image existing images:"
    docker image ls $IMAGE
diff --cc pom.xml
+++ b/pom.xml
    </parent>
  
    <groupId>de.juplo.kafka</groupId>
 -  <artifactId>sumup-adder</artifactId>
 +  <artifactId>endless-consumer</artifactId>
    <version>1.0-SNAPSHOT</version>
 -  <name>SumUp Adder</name>
 -  <description>Calculates the sum for the send messages</description>
 +  <name>Endless Consumer: a Simple Consumer-Group that reads and prints the topic and counts the received messages for each key by topic</name>
  
+   <properties>
+     <java.version>11</java.version>
+   </properties>
    <dependencies>
      <dependency>
        <groupId>org.springframework.boot</groupId>
@@@ -22,9 -22,10 +22,10 @@@ public class ApplicationRebalanceListen
    private final String topic;
    private final Clock clock;
    private final Duration commitInterval;
 -  private final Consumer<String, String> consumer;
 +  private final Consumer<String, Long> consumer;
  
    private Instant lastCommit = Instant.EPOCH;
+   private boolean commitsEnabled = true;
  
    @Override
    public void onPartitionsAssigned(Collection<TopicPartition> partitions)
  package de.juplo.kafka;
  
- import lombok.extern.slf4j.Slf4j;
 +import org.apache.kafka.clients.consumer.ConsumerRecord;
- import org.apache.kafka.clients.consumer.KafkaConsumer;
- import org.apache.kafka.clients.producer.KafkaProducer;
  import org.apache.kafka.clients.producer.ProducerRecord;
- import org.apache.kafka.common.TopicPartition;
- import org.apache.kafka.common.errors.RecordDeserializationException;
- import org.apache.kafka.common.serialization.*;
++import org.apache.kafka.common.serialization.LongSerializer;
+ import org.apache.kafka.common.serialization.StringSerializer;
  import org.apache.kafka.common.utils.Bytes;
- import org.junit.jupiter.api.*;
- import org.springframework.beans.factory.annotation.Autowired;
- import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
- import org.springframework.boot.test.autoconfigure.data.mongo.AutoConfigureDataMongo;
- import org.springframework.boot.test.context.ConfigDataApplicationContextInitializer;
 +import org.springframework.boot.test.context.TestConfiguration;
 +import org.springframework.context.annotation.Bean;
- import org.springframework.context.annotation.Import;
- import org.springframework.kafka.test.context.EmbeddedKafka;
- import org.springframework.test.context.TestPropertySource;
- import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
++import org.springframework.context.annotation.Primary;
++import org.springframework.test.context.ContextConfiguration;
  
- import java.time.Duration;
- import java.util.*;
- import java.util.concurrent.ExecutionException;
- import java.util.concurrent.ExecutorService;
- import java.util.function.BiConsumer;
- import java.util.stream.Collectors;
- import java.util.stream.IntStream;
+ import java.util.function.Consumer;
 -import java.util.stream.IntStream;
  
- import static de.juplo.kafka.ApplicationTests.PARTITIONS;
- import static de.juplo.kafka.ApplicationTests.TOPIC;
- import static org.assertj.core.api.Assertions.*;
- import static org.awaitility.Awaitility.*;
  
- @SpringJUnitConfig(initializers = ConfigDataApplicationContextInitializer.class)
- @TestMethodOrder(MethodOrderer.OrderAnnotation.class)
- @TestPropertySource(
-               properties = {
-                               "consumer.bootstrap-server=${spring.embedded.kafka.brokers}",
-                               "consumer.topic=" + TOPIC,
-                               "consumer.commit-interval=1s",
-                               "spring.mongodb.embedded.version=4.4.13" })
- @EmbeddedKafka(topics = TOPIC, partitions = PARTITIONS)
- @EnableAutoConfiguration
- @AutoConfigureDataMongo
- @Slf4j
- class ApplicationTests
 -public class ApplicationTests extends GenericApplicationTests<String, String>
++@ContextConfiguration(classes = ApplicationTests.Configuration.class)
++public class ApplicationTests extends GenericApplicationTests<String, Long>
  {
-       public static final String TOPIC = "FOO";
-       public static final int PARTITIONS = 10;
-       StringSerializer stringSerializer = new StringSerializer();
-       @Autowired
-       Serializer valueSerializer;
-       @Autowired
-       KafkaProducer<String, Bytes> kafkaProducer;
-       @Autowired
-       KafkaConsumer<String, Long> kafkaConsumer;
-       @Autowired
-       KafkaConsumer<Bytes, Bytes> offsetConsumer;
-       @Autowired
-       ApplicationProperties properties;
-       @Autowired
-       ExecutorService executor;
-       @Autowired
-   StateRepository stateRepository;
-       @Autowired
-   ApplicationRebalanceListener rebalanceListener;
-       @Autowired
-   ApplicationRecordHandler recordHandler;
-       EndlessConsumer<String, Long> endlessConsumer;
-       Map<TopicPartition, Long> oldOffsets;
-       Map<TopicPartition, Long> newOffsets;
-       Set<ConsumerRecord<String, Long>> receivedRecords;
-       /** Tests methods */
-       @Test
-       void commitsCurrentOffsetsOnSuccess() throws ExecutionException, InterruptedException
-       {
-               send100Messages((partition, key, counter) ->
-               {
-                       Bytes value = new Bytes(valueSerializer.serialize(TOPIC, counter));
-                       return new ProducerRecord<>(TOPIC, partition, key, value);
-               });
-               await("100 records received")
-                               .atMost(Duration.ofSeconds(30))
-                               .pollInterval(Duration.ofSeconds(1))
-                               .until(() -> receivedRecords.size() >= 100);
-               await("Offsets committed")
-                               .atMost(Duration.ofSeconds(10))
-                               .pollInterval(Duration.ofSeconds(1))
-                               .untilAsserted(() ->
-                               {
-                                       checkSeenOffsetsForProgress();
-                                       compareToCommitedOffsets(newOffsets);
-                               });
-               assertThatExceptionOfType(IllegalStateException.class)
-                               .isThrownBy(() -> endlessConsumer.exitStatus())
-                               .describedAs("Consumer should still be running");
-       }
-       @Test
-       void commitsOffsetOfErrorForReprocessingOnDeserializationError()
-       {
-               send100Messages((partition, key, counter) ->
-               {
-                       Bytes value = counter == 77
-                                       ? new Bytes(stringSerializer.serialize(TOPIC, "BOOM!"))
-                                       : new Bytes(valueSerializer.serialize(TOPIC, counter));
-                       return new ProducerRecord<>(TOPIC, partition, key, value);
-               });
-               await("Consumer failed")
-                               .atMost(Duration.ofSeconds(30))
-                               .pollInterval(Duration.ofSeconds(1))
-                               .until(() -> !endlessConsumer.running());
-               checkSeenOffsetsForProgress();
-               compareToCommitedOffsets(newOffsets);
-               endlessConsumer.start();
-               await("Consumer failed")
-                               .atMost(Duration.ofSeconds(30))
-                               .pollInterval(Duration.ofSeconds(1))
-                               .until(() -> !endlessConsumer.running());
-               checkSeenOffsetsForProgress();
-               compareToCommitedOffsets(newOffsets);
-               assertThat(receivedRecords.size())
-                               .describedAs("Received not all sent events")
-                               .isLessThan(100);
-               assertThatNoException()
-                               .describedAs("Consumer should not be running")
-                               .isThrownBy(() -> endlessConsumer.exitStatus());
-               assertThat(endlessConsumer.exitStatus())
-                               .describedAs("Consumer should have exited abnormally")
-                               .containsInstanceOf(RecordDeserializationException.class);
-       }
-       /** Helper methods for the verification of expectations */
-       void compareToCommitedOffsets(Map<TopicPartition, Long> offsetsToCheck)
-       {
-               doForCurrentOffsets((tp, offset) ->
-               {
-                       Long expected = offsetsToCheck.get(tp) + 1;
-                       log.debug("Checking, if the offset for {} is {}", tp, expected);
-                       assertThat(offset)
-                                       .describedAs("Committed offset corresponds to the offset of the consumer")
-                                       .isEqualTo(expected);
-               });
-       }
-       void checkSeenOffsetsForProgress()
-       {
-               // Be sure, that some messages were consumed...!
-               Set<TopicPartition> withProgress = new HashSet<>();
-               partitions().forEach(tp ->
-               {
-                       Long oldOffset = oldOffsets.get(tp) + 1;
-                       Long newOffset = newOffsets.get(tp) + 1;
-                       if (!oldOffset.equals(newOffset))
-                       {
-                               log.debug("Progress for {}: {} -> {}", tp, oldOffset, newOffset);
-                               withProgress.add(tp);
-                       }
-               });
-               assertThat(withProgress)
-                               .describedAs("Some offsets must have changed, compared to the old offset-positions")
-                               .isNotEmpty();
-       }
-       /** Helper methods for setting up and running the tests */
-       void seekToEnd()
-       {
-               offsetConsumer.assign(partitions());
-               partitions().forEach(tp ->
-               {
-                       Long offset = offsetConsumer.position(tp);
-                       log.info("New position for {}: {}", tp, offset);
-                       Integer partition = tp.partition();
-                       StateDocument document =
-                                       stateRepository
-                                                       .findById(partition.toString())
-                                                       .orElse(new StateDocument(partition));
-                       document.offset = offset;
-                       stateRepository.save(document);
-               });
-               offsetConsumer.unsubscribe();
-       }
-       void doForCurrentOffsets(BiConsumer<TopicPartition, Long> consumer)
-       {
-               partitions().forEach(tp ->
-               {
-                       String partition = Integer.toString(tp.partition());
-                       Optional<Long> offset = stateRepository.findById(partition).map(document -> document.offset);
-                       consumer.accept(tp, offset.orElse(0l));
-               });
-               }
-       List<TopicPartition> partitions()
-       {
-               return
-                               IntStream
-                                               .range(0, PARTITIONS)
-                                               .mapToObj(partition -> new TopicPartition(TOPIC, partition))
-                                               .collect(Collectors.toList());
-       }
-       public interface RecordGenerator<K, V>
-       {
-               public ProducerRecord<String, Bytes> generate(int partition, String key, long counter);
-       }
-       void send100Messages(RecordGenerator recordGenerator)
-       {
-               long i = 0;
-               for (int partition = 0; partition < 10; partition++)
-               {
-                       for (int key = 0; key < 10; key++)
-                       {
-                               ProducerRecord<String, Bytes> record =
-                                               recordGenerator.generate(partition, Integer.toString(partition*10+key%2), ++i);
-                               kafkaProducer.send(record, (metadata, e) ->
-                               {
-                                       if (metadata != null)
-                                       {
-                                               log.debug(
-                                                               "{}|{} - {}={}",
-                                                               metadata.partition(),
-                                                               metadata.offset(),
-                                                               record.key(),
-                                                               record.value());
-                                       }
-                                       else
-                                       {
-                                               log.warn(
-                                                               "Exception for {}={}: {}",
-                                                               record.key(),
-                                                               record.value(),
-                                                               e.toString());
-                                       }
-                               });
-                       }
-               }
-       }
-       @BeforeEach
-       public void init()
-       {
-               seekToEnd();
-               oldOffsets = new HashMap<>();
-               newOffsets = new HashMap<>();
-               receivedRecords = new HashSet<>();
-               doForCurrentOffsets((tp, offset) ->
-               {
-                       oldOffsets.put(tp, offset - 1);
-                       newOffsets.put(tp, offset - 1);
-               });
-               TestRecordHandler<String, Long> captureOffsetAndExecuteTestHandler =
-                               new TestRecordHandler<String, Long>(recordHandler) {
-                                       @Override
-                                       public void onNewRecord(ConsumerRecord<String, Long> record)
-                                       {
-                                               newOffsets.put(
-                                                               new TopicPartition(record.topic(), record.partition()),
-                                                               record.offset());
-                                               receivedRecords.add(record);
-                                       }
-                               };
-               endlessConsumer =
-                               new EndlessConsumer<>(
-                                               executor,
-                                               properties.getClientId(),
-                                               properties.getTopic(),
-                                               kafkaConsumer,
-             rebalanceListener,
-                                               captureOffsetAndExecuteTestHandler);
-               endlessConsumer.start();
-       }
-       @AfterEach
-       public void deinit()
-       {
-               try
-               {
-                       endlessConsumer.stop();
-               }
-               catch (Exception e)
-               {
-                       log.info("Exception while stopping the consumer: {}", e.toString());
-               }
-       }
-       @TestConfiguration
-       @Import(ApplicationConfiguration.class)
-       public static class Configuration
-       {
-               @Bean
-               Serializer<Long> serializer()
-               {
-                       return new LongSerializer();
-               }
-               @Bean
-               KafkaProducer<String, Bytes> kafkaProducer(ApplicationProperties properties)
-               {
-                       Properties props = new Properties();
-                       props.put("bootstrap.servers", properties.getBootstrapServer());
-                       props.put("linger.ms", 100);
-                       props.put("key.serializer", StringSerializer.class.getName());
-                       props.put("value.serializer", BytesSerializer.class.getName());
-                       return new KafkaProducer<>(props);
-               }
-               @Bean
-               KafkaConsumer<Bytes, Bytes> offsetConsumer(ApplicationProperties properties)
-               {
-                       Properties props = new Properties();
-                       props.put("bootstrap.servers", properties.getBootstrapServer());
-                       props.put("client.id", "OFFSET-CONSUMER");
-                       props.put("enable.auto.commit", false);
-                       props.put("auto.offset.reset", "latest");
-                       props.put("key.deserializer", BytesDeserializer.class.getName());
-                       props.put("value.deserializer", BytesDeserializer.class.getName());
-                       return new KafkaConsumer<>(props);
-               }
-       }
+   public ApplicationTests()
+   {
+     super(
+         new RecordGenerator()
+         {
 -          final int[] numbers = { 1, 7, 3, 2, 33, 6, 11 };
 -          final String[] dieWilden13 =
 -              IntStream
 -                  .range(1,14)
 -                  .mapToObj(i -> "seeräuber-" + i)
 -                  .toArray(i -> new String[i]);
+           final StringSerializer stringSerializer = new StringSerializer();
 -          final Bytes startMessage = new Bytes(stringSerializer.serialize(TOPIC, "START"));
 -          final Bytes endMessage = new Bytes(stringSerializer.serialize(TOPIC, "END"));
 -
 -          int counter = 0;
++          final LongSerializer longSerializer = new LongSerializer();
+           @Override
+           public int generate(
+               boolean poisonPills,
+               boolean logicErrors,
+               Consumer<ProducerRecord<Bytes, Bytes>> messageSender)
+           {
 -            counter = 0;
++            int i = 0;
 -            for (int i = 0; i < 33; i++)
++            for (int partition = 0; partition < 10; partition++)
+             {
 -              String seeräuber = dieWilden13[i%13];
 -              int number = numbers[i%7];
 -
 -              Bytes key = new Bytes(stringSerializer.serialize(TOPIC, seeräuber));
 -
 -              send(key, startMessage, logicErrors, messageSender);
 -              for (int message = 1; message <= number; message++)
++              for (int key = 0; key < 10; key++)
+               {
 -                Bytes value = new Bytes(stringSerializer.serialize(TOPIC, Integer.toString(message)));
 -                send(key, value, logicErrors, messageSender);
 -              }
 -              send(key, endMessage, logicErrors, messageSender);
 -            }
++                i++;
 -            return counter;
 -          }
++                Bytes value = new Bytes(longSerializer.serialize(TOPIC, (long)i));
++                if (i == 77)
++                {
++                  if (logicErrors)
++                  {
++                    value = new Bytes(longSerializer.serialize(TOPIC, Long.MIN_VALUE));
++                  }
++                  if (poisonPills)
++                  {
++                    value = new Bytes(stringSerializer.serialize(TOPIC, "BOOM (Poison-Pill)!"));
++                  }
++                }
 -          void send(
 -              Bytes key,
 -              Bytes value,
 -              boolean logicErrors,
 -              Consumer<ProducerRecord<Bytes, Bytes>> messageSender)
 -          {
 -            counter++;
++                ProducerRecord<Bytes, Bytes> record =
++                    new ProducerRecord<>(
++                        TOPIC,
++                        partition,
++                        new Bytes(stringSerializer.serialize(TOPIC,Integer.toString(partition*10+key%2))),
++                        value);
 -            if (counter == 77)
 -            {
 -              if (logicErrors)
 -              {
 -                value = value.equals(startMessage) ? endMessage : startMessage;
++                messageSender.accept(record);
+               }
+             }
 -            messageSender.accept(new ProducerRecord<>(TOPIC, key, value));
 -          }
 -
 -          @Override
 -          public boolean canGeneratePoisonPill()
 -          {
 -            return false;
++            return i;
+           }
+         });
+   }
++
++
++  @TestConfiguration
++  public static class Configuration
++  {
++    @Primary
++    @Bean
++    public ApplicationRecordHandler recordHandler()
++    {
++      ApplicationRecordHandler recordHandler = new ApplicationRecordHandler();
++      return new ApplicationRecordHandler()
++      {
++        @Override
++        public void accept(ConsumerRecord<String, Long> record)
++        {
++          if (record.value() == Long.MIN_VALUE)
++            throw new RuntimeException("BOOM (Logic-Error)!");
++          super.accept(record);
++        }
++      };
++    }
++  }
  }
index 0000000,9a6f812..fa3d911
mode 000000,100644..100644
--- /dev/null
@@@ -1,0 -1,390 +1,390 @@@
 -                              "sumup.adder.bootstrap-server=${spring.embedded.kafka.brokers}",
 -                              "sumup.adder.topic=" + TOPIC,
 -                              "sumup.adder.commit-interval=1s",
+ package de.juplo.kafka;
+ import lombok.extern.slf4j.Slf4j;
+ import org.apache.kafka.clients.consumer.ConsumerRecord;
+ import org.apache.kafka.clients.consumer.KafkaConsumer;
+ import org.apache.kafka.clients.producer.KafkaProducer;
+ import org.apache.kafka.clients.producer.ProducerRecord;
+ import org.apache.kafka.common.TopicPartition;
+ import org.apache.kafka.common.errors.RecordDeserializationException;
+ import org.apache.kafka.common.serialization.*;
+ import org.apache.kafka.common.utils.Bytes;
+ import org.junit.jupiter.api.*;
+ import org.springframework.beans.factory.annotation.Autowired;
+ import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+ import org.springframework.boot.test.autoconfigure.data.mongo.AutoConfigureDataMongo;
+ import org.springframework.boot.test.context.ConfigDataApplicationContextInitializer;
+ import org.springframework.boot.test.context.TestConfiguration;
+ import org.springframework.context.annotation.Import;
+ import org.springframework.kafka.test.context.EmbeddedKafka;
+ import org.springframework.test.context.TestPropertySource;
+ import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+ import java.time.Duration;
+ import java.util.*;
+ import java.util.concurrent.ExecutorService;
+ import java.util.function.BiConsumer;
+ import java.util.function.Consumer;
+ import java.util.stream.Collectors;
+ import java.util.stream.IntStream;
+ import static de.juplo.kafka.GenericApplicationTests.PARTITIONS;
+ import static de.juplo.kafka.GenericApplicationTests.TOPIC;
+ import static org.assertj.core.api.Assertions.*;
+ import static org.awaitility.Awaitility.*;
+ @SpringJUnitConfig(initializers = ConfigDataApplicationContextInitializer.class)
+ @TestPropertySource(
+               properties = {
++                              "consumer.bootstrap-server=${spring.embedded.kafka.brokers}",
++                              "consumer.topic=" + TOPIC,
++                              "consumer.commit-interval=1s",
+                               "spring.mongodb.embedded.version=4.4.13" })
+ @EmbeddedKafka(topics = TOPIC, partitions = PARTITIONS)
+ @EnableAutoConfiguration
+ @AutoConfigureDataMongo
+ @Slf4j
+ abstract class GenericApplicationTests<K, V>
+ {
+       public static final String TOPIC = "FOO";
+       public static final int PARTITIONS = 10;
+       @Autowired
+       KafkaConsumer<K, V> kafkaConsumer;
+       @Autowired
+       Consumer<ConsumerRecord<K, V>> consumer;
+       @Autowired
+       ApplicationProperties properties;
+       @Autowired
+       ExecutorService executor;
+       @Autowired
+       StateRepository stateRepository;
+       @Autowired
+       PollIntervalAwareConsumerRebalanceListener rebalanceListener;
+       @Autowired
+       RecordHandler<K, V> recordHandler;
+       KafkaProducer<Bytes, Bytes> testRecordProducer;
+       KafkaConsumer<Bytes, Bytes> offsetConsumer;
+       EndlessConsumer<K, V> endlessConsumer;
+       Map<TopicPartition, Long> oldOffsets;
+       Map<TopicPartition, Long> newOffsets;
+       Set<ConsumerRecord<K, V>> receivedRecords;
+       final RecordGenerator recordGenerator;
+       final Consumer<ProducerRecord<Bytes, Bytes>> messageSender;
+       public GenericApplicationTests(RecordGenerator recordGenerator)
+       {
+               this.recordGenerator = recordGenerator;
+               this.messageSender = (record) -> sendMessage(record);
+       }
+       /** Tests methods */
+       @Test
+       void commitsCurrentOffsetsOnSuccess()
+       {
+               int numberOfGeneratedMessages =
+                               recordGenerator.generate(false, false, messageSender);
+               await(numberOfGeneratedMessages + " records received")
+                               .atMost(Duration.ofSeconds(30))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .until(() -> receivedRecords.size() >= numberOfGeneratedMessages);
+               await("Offsets committed")
+                               .atMost(Duration.ofSeconds(10))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .untilAsserted(() ->
+                               {
+                                       checkSeenOffsetsForProgress();
+                                       compareToCommitedOffsets(newOffsets);
+                               });
+               assertThatExceptionOfType(IllegalStateException.class)
+                               .isThrownBy(() -> endlessConsumer.exitStatus())
+                               .describedAs("Consumer should still be running");
+               recordGenerator.assertBusinessLogic();
+       }
+       @Test
+       @SkipWhenErrorCannotBeGenerated(poisonPill = true)
+       void commitsOffsetOfErrorForReprocessingOnDeserializationError()
+       {
+               int numberOfGeneratedMessages =
+                               recordGenerator.generate(true, false, messageSender);
+               await("Consumer failed")
+                               .atMost(Duration.ofSeconds(30))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .until(() -> !endlessConsumer.running());
+               checkSeenOffsetsForProgress();
+               compareToCommitedOffsets(newOffsets);
+               endlessConsumer.start();
+               await("Consumer failed")
+                               .atMost(Duration.ofSeconds(30))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .until(() -> !endlessConsumer.running());
+               checkSeenOffsetsForProgress();
+               compareToCommitedOffsets(newOffsets);
+               assertThat(receivedRecords.size())
+                               .describedAs("Received not all sent events")
+                               .isLessThan(numberOfGeneratedMessages);
+               assertThatNoException()
+                               .describedAs("Consumer should not be running")
+                               .isThrownBy(() -> endlessConsumer.exitStatus());
+               assertThat(endlessConsumer.exitStatus())
+                               .describedAs("Consumer should have exited abnormally")
+                               .containsInstanceOf(RecordDeserializationException.class);
+               recordGenerator.assertBusinessLogic();
+       }
+       @Test
+       @SkipWhenErrorCannotBeGenerated(logicError = true)
+       void doesNotCommitOffsetsOnLogicError()
+       {
+               int numberOfGeneratedMessages =
+                               recordGenerator.generate(false, true, messageSender);
+               await("Consumer failed")
+                               .atMost(Duration.ofSeconds(30))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .until(() -> !endlessConsumer.running());
+               checkSeenOffsetsForProgress();
+               compareToCommitedOffsets(oldOffsets);
+               endlessConsumer.start();
+               await("Consumer failed")
+                               .atMost(Duration.ofSeconds(30))
+                               .pollInterval(Duration.ofSeconds(1))
+                               .until(() -> !endlessConsumer.running());
+               checkSeenOffsetsForProgress();
+               compareToCommitedOffsets(oldOffsets);
+               assertThat(receivedRecords.size())
+                               .describedAs("Received not all sent events")
+                               .isLessThan(numberOfGeneratedMessages);
+               assertThatNoException()
+                               .describedAs("Consumer should not be running")
+                               .isThrownBy(() -> endlessConsumer.exitStatus());
+               assertThat(endlessConsumer.exitStatus())
+                               .describedAs("Consumer should have exited abnormally")
+                               .containsInstanceOf(RuntimeException.class);
+               recordGenerator.assertBusinessLogic();
+       }
+       /** Helper methods for the verification of expectations */
+       void compareToCommitedOffsets(Map<TopicPartition, Long> offsetsToCheck)
+       {
+               doForCurrentOffsets((tp, offset) ->
+               {
+                       Long expected = offsetsToCheck.get(tp) + 1;
+                       log.debug("Checking, if the offset for {} is {}", tp, expected);
+                       assertThat(offset)
+                                       .describedAs("Committed offset corresponds to the offset of the consumer")
+                                       .isEqualTo(expected);
+               });
+       }
+       void checkSeenOffsetsForProgress()
+       {
+               // Be sure, that some messages were consumed...!
+               Set<TopicPartition> withProgress = new HashSet<>();
+               partitions().forEach(tp ->
+               {
+                       Long oldOffset = oldOffsets.get(tp) + 1;
+                       Long newOffset = newOffsets.get(tp) + 1;
+                       if (!oldOffset.equals(newOffset))
+                       {
+                               log.debug("Progress for {}: {} -> {}", tp, oldOffset, newOffset);
+                               withProgress.add(tp);
+                       }
+               });
+               assertThat(withProgress)
+                               .describedAs("Some offsets must have changed, compared to the old offset-positions")
+                               .isNotEmpty();
+       }
+       /** Helper methods for setting up and running the tests */
+       void seekToEnd()
+       {
+               offsetConsumer.assign(partitions());
+               partitions().forEach(tp ->
+               {
+                       Long offset = offsetConsumer.position(tp);
+                       log.info("New position for {}: {}", tp, offset);
+                       Integer partition = tp.partition();
+                       StateDocument document =
+                                       stateRepository
+                                                       .findById(partition.toString())
+                                                       .orElse(new StateDocument(partition));
+                       document.offset = offset;
+                       stateRepository.save(document);
+               });
+               offsetConsumer.unsubscribe();
+       }
+       void doForCurrentOffsets(BiConsumer<TopicPartition, Long> consumer)
+       {
+               partitions().forEach(tp ->
+               {
+                       String partition = Integer.toString(tp.partition());
+                       Optional<Long> offset = stateRepository.findById(partition).map(document -> document.offset);
+                       consumer.accept(tp, offset.orElse(0l));
+               });
+       }
+       List<TopicPartition> partitions()
+       {
+               return
+                               IntStream
+                                               .range(0, PARTITIONS)
+                                               .mapToObj(partition -> new TopicPartition(TOPIC, partition))
+                                               .collect(Collectors.toList());
+       }
+       public interface RecordGenerator
+       {
+               int generate(
+                               boolean poisonPills,
+                               boolean logicErrors,
+                               Consumer<ProducerRecord<Bytes, Bytes>> messageSender);
+               default boolean canGeneratePoisonPill()
+               {
+                       return true;
+               }
+               default boolean canGenerateLogicError()
+               {
+                       return true;
+               }
+               default void assertBusinessLogic()
+               {
+                       log.debug("No business-logic to assert");
+               }
+       }
+       void sendMessage(ProducerRecord<Bytes, Bytes> record)
+       {
+               testRecordProducer.send(record, (metadata, e) ->
+               {
+                       if (metadata != null)
+                       {
+                               log.debug(
+                                               "{}|{} - {}={}",
+                                               metadata.partition(),
+                                               metadata.offset(),
+                                               record.key(),
+                                               record.value());
+                       }
+                       else
+                       {
+                               log.warn(
+                                               "Exception for {}={}: {}",
+                                               record.key(),
+                                               record.value(),
+                                               e.toString());
+                       }
+               });
+       }
+       @BeforeEach
+       public void init()
+       {
+               Properties props;
+               props = new Properties();
+               props.put("bootstrap.servers", properties.getBootstrapServer());
+               props.put("linger.ms", 100);
+               props.put("key.serializer", BytesSerializer.class.getName());
+               props.put("value.serializer", BytesSerializer.class.getName());
+               testRecordProducer = new KafkaProducer<>(props);
+               props = new Properties();
+               props.put("bootstrap.servers", properties.getBootstrapServer());
+               props.put("client.id", "OFFSET-CONSUMER");
+               props.put("group.id", properties.getGroupId());
+               props.put("key.deserializer", BytesDeserializer.class.getName());
+               props.put("value.deserializer", BytesDeserializer.class.getName());
+               offsetConsumer = new KafkaConsumer<>(props);
+               seekToEnd();
+               oldOffsets = new HashMap<>();
+               newOffsets = new HashMap<>();
+               receivedRecords = new HashSet<>();
+               doForCurrentOffsets((tp, offset) ->
+               {
+                       oldOffsets.put(tp, offset - 1);
+                       newOffsets.put(tp, offset - 1);
+               });
+               TestRecordHandler<K, V> captureOffsetAndExecuteTestHandler =
+                               new TestRecordHandler<K, V>(recordHandler)
+                               {
+                                       @Override
+                                       public void onNewRecord(ConsumerRecord<K, V> record)
+                                       {
+                                               newOffsets.put(
+                                                               new TopicPartition(record.topic(), record.partition()),
+                                                               record.offset());
+                                               receivedRecords.add(record);
+                                       }
+                               };
+               endlessConsumer =
+                               new EndlessConsumer<>(
+                                               executor,
+                                               properties.getClientId(),
+                                               properties.getTopic(),
+                                               kafkaConsumer,
+                                               rebalanceListener,
+                                               captureOffsetAndExecuteTestHandler);
+               endlessConsumer.start();
+       }
+       @AfterEach
+       public void deinit()
+       {
+               try
+               {
+                       endlessConsumer.stop();
+                       testRecordProducer.close();
+                       offsetConsumer.close();
+               }
+               catch (Exception e)
+               {
+                       log.info("Exception while stopping the consumer: {}", e.toString());
+               }
+       }
+       @TestConfiguration
+       @Import(ApplicationConfiguration.class)
+       public static class Configuration
+       {
+       }
+ }