@Override
  public void describe(StreamApplicationDescriptor appDescriptor) {
    KafkaSystemDescriptor ksd = new KafkaSystemDescriptor(systemName);
    KafkaOutputDescriptor<String> osd = ksd.getOutputDescriptor(outputTopic, new StringSerde());
    OutputStream<String> outputStream = appDescriptor.getOutputStream(osd);

    for (String inputTopic : inputTopics) {
      KafkaInputDescriptor<String> isd = ksd.getInputDescriptor(inputTopic, new NoOpSerde<>());
      MessageStream<String> inputStream = appDescriptor.getInputStream(isd);
      inputStream.map(new TestMapFunction(appName, processorName)).sendTo(outputStream);
    }
  }
Test class to create an {@link StreamApplication} instance
samza-test/src/test/java/org/apache/samza/test/processor/TestStreamApplication.java