@Test
public void testRetrieveGroupFromEngine() {

    Optional<Group> result = engineManager.retrieveGroup(ERROR, "group");
    verify(engine, times(0)).retrieveGroup("group");
    assertFalse(result.isPresent());
    result = engineManager.retrieveGroup(engine.getEngineName(), "group");
    verify(engine).retrieveGroup("group");
    assertTrue(result.isPresent());
    assertEquals(group, result.get());
}