@Override
  public List<String> getGroups(String user) {
    return Collections.emptyList();
  }
@Test
  public void testGetGroups() {
    String user = "user";
    List<String> expResult = Collections.emptyList();
    List<String> result = ngm.getGroups(user);

    assertEquals("No groups should be returned",
        expResult, result);

    ngm.cacheGroupsAdd(Arrays.asList(new String[] {"group1", "group2"}));
    result = ngm.getGroups(user);

    assertEquals("No groups should be returned",
        expResult, result);

    ngm.cacheGroupsRefresh();
    result = ngm.getGroups(user);

    assertEquals("No groups should be returned",
        expResult, result);
  }