### Question:
TezClientUtils { static void maybeAddDefaultLoggingJavaOpts(String logLevel, List<String> vargs) { if (vargs != null && !vargs.isEmpty()) { for (String arg : vargs) { if (arg.contains(TezConfiguration.TEZ_ROOT_LOGGER_NAME)) { return ; } } } TezClientUtils.addLog4jSystemProperties(logLevel, vargs); }  static FileSystem ensureStagingDirExists(Configuration conf,
      Path stagingArea); @Private @VisibleForTesting static void addLog4jSystemProperties(String logLevel,
      List<String> vargs); @Private static DAGClientAMProtocolBlockingPB getAMProxy(final Configuration conf, String amHost,
      int amRpcPort, org.apache.hadoop.yarn.api.records.Token clientToAMToken); @Private static void createSessionToken(String tokenIdentifier,
      JobTokenSecretManager jobTokenSecretManager,
      Credentials credentials); static String maybeAddDefaultMemoryJavaOpts(String javaOpts, Resource resource,
      double maxHeapFactor);  }### Answer:
@Test (timeout=5000) public void testDefaultLoggingJavaOpts() { String origJavaOpts = null; String javaOpts = TezClientUtils.maybeAddDefaultLoggingJavaOpts("FOOBAR", origJavaOpts); Assert.assertNotNull(javaOpts); Assert.assertTrue(javaOpts.contains("-D" + TezConfiguration.TEZ_ROOT_LOGGER_NAME + "=FOOBAR") && javaOpts.contains(TezConfiguration.TEZ_CONTAINER_LOG4J_PROPERTIES_FILE)); }