@Override
  public List<String> getGroups(String userName) throws IOException {
    return new ArrayList(getUnixGroups(userName));
  }
@Test
  public void testGetGroupsNotResolvable() throws Exception {
    TestGroupNotResolvable mapping = new TestGroupNotResolvable();

    List<String> groups = mapping.getGroups("user");
    assertTrue(groups.size() == 2);
    assertTrue(groups.contains("abc"));
    assertTrue(groups.contains("def"));
  }