@VisibleForTesting
  public long getTimeout() {
    return timeout;
  }
@Test
  public void testUserUpdateSetting() throws IOException {
    ShellBasedIdMapping iug = new ShellBasedIdMapping(new Configuration());
    assertThat(iug.getTimeout()).isEqualTo(
        IdMappingConstant.USERGROUPID_UPDATE_MILLIS_DEFAULT);

    Configuration conf = new Configuration();
    conf.setLong(IdMappingConstant.USERGROUPID_UPDATE_MILLIS_KEY, 0);
    iug = new ShellBasedIdMapping(conf);
    assertThat(iug.getTimeout()).isEqualTo(
        IdMappingConstant.USERGROUPID_UPDATE_MILLIS_MIN);

    conf.setLong(IdMappingConstant.USERGROUPID_UPDATE_MILLIS_KEY,
        IdMappingConstant.USERGROUPID_UPDATE_MILLIS_DEFAULT * 2);
    iug = new ShellBasedIdMapping(conf);
    assertThat(iug.getTimeout()).isEqualTo(
        IdMappingConstant.USERGROUPID_UPDATE_MILLIS_DEFAULT * 2);
  }