@Test
public void testDefaultConfUsed() {

  Configuration conf = getConf();
  conf.unset(YarnConfiguration.NM_REMOTE_APP_LOG_DIR);
  conf.unset(YarnConfiguration.NM_REMOTE_APP_LOG_DIR_SUFFIX);
  conf.set(YarnConfiguration.LOG_AGGREGATION_FILE_FORMATS, "TFile");
  LogAggregationFileControllerFactory factory =
      new LogAggregationFileControllerFactory(getConf());
  LogAggregationFileController fc = factory.getFileControllerForWrite();
  assertEquals(WRONG_ROOT_LOG_DIR_MSG, "/tmp/logs",
      fc.getRemoteRootLogDir().toString());
  assertEquals(WRONG_ROOT_LOG_DIR_SUFFIX_MSG, "logs-tfile",
      fc.getRemoteRootLogDirSuffix());
}