@Test
public void testSimpleMapping() {

    DefaultRoleToGroupMapper mapper = new DefaultRoleToGroupMapper();
    List<String> result = mapper.groupsFromRoles(Arrays.asList("Role1", "Role2", "Role3"));
    assertNotNull(result);
    assertEquals(3, result.size());
    assertEquals("Role1", result.get(0));
    assertEquals("Role3", result.get(2));
}