private void deleteDirectory(String path) {
    File dir = new File(path);
    LOG.info("Deleting the directory " + path);
    new FileUtil().rm(dir);
    if (dir.exists()) {
      LOG.warn("Could not delete the directory " + path);
    }
  }
Creates an in memory stream with {@link InMemorySystemFactory} and feeds its partition with stream of messages
@param partitionData key of the map represents partitionId and value represents messages in the partition
@param descriptor describes a stream to initialize with the in memory system
samza-test/src/main/java/org/apache/samza/test/framework/TestRunner.java