@Test
public void testFindObservation_notInCoincidences_detaches() {

    final Matchup matchup = createMatchupWithRefObs("different");
    final List<Coincidence> coincidences = new ArrayList<>();
    final Observation observation = new Observation();
    observation.setSensor("also_different");
    final Coincidence coincidence = new Coincidence();
    coincidence.setObservation(observation);
    coincidences.add(coincidence);
    matchup.setCoincidences(coincidences);
    final PersistenceManager persistenceManager = mock(PersistenceManager.class);
    final Observation result = MmdTool.findObservation("the_one", matchup, persistenceManager);
    assertNull(result);
    verify(persistenceManager, times(1)).detach(observation);
    verify(persistenceManager, times(1)).detach(coincidence);
    verifyNoMoreInteractions(persistenceManager);
}