@Override
  public void describe(StreamApplicationDescriptor appDescriptor) {
    String systemName = "testSystemName";
    String inputStreamName = appDescriptor.getConfig().get("input.stream.name");
    String outputStreamName = "standaloneIntegrationTestKafkaOutputTopic";
    LOGGER.info("Publishing message from: {} to: {}.", inputStreamName, outputStreamName);
    KafkaSystemDescriptor kafkaSystemDescriptor = new KafkaSystemDescriptor(systemName);

    KVSerde<Object, Object> noOpSerde = KVSerde.of(new NoOpSerde<>(), new NoOpSerde<>());
    KafkaInputDescriptor<KV<Object, Object>> isd =
        kafkaSystemDescriptor.getInputDescriptor(inputStreamName, noOpSerde);
    KafkaOutputDescriptor<KV<Object, Object>> osd =
        kafkaSystemDescriptor.getOutputDescriptor(outputStreamName, noOpSerde);
    appDescriptor.getInputStream(isd).sendTo(appDescriptor.getOutputStream(osd));
  }
Acts as a pass through filter for all the events from a input stream.
samza-test/src/main/java/org/apache/samza/test/integration/TestStandaloneIntegrationApplication.java