@Test
  public void shouldRemoveEmail() {
    OutsiderTeacher teacher = scenarioHelper.createOutsiderTeacher();

    assertThat(teacher.getContact().getEmails()).isNotEmpty();

    for (Email email : teacher.getContact().getEmails()) {
      outsiderTeacherManager.removeEmail(email.getId());
    }
    assertThat(outsiderTeacherManager.findOneById(teacher.getId()).getContact().getEmails())
        .isEmpty();
    assertThat(emailRepository.findAll()).isEmpty();
  }
  @Test
  public void shouldAddEmail() {
    OutsiderTeacher teacher = scenarioHelper.createEmptyOutsiderTeacher();
    Email email = EmailTest.createOne(scenarioHelper.createEmailType());

    assertThat(outsiderTeacherManager.findOneById(teacher.getId()).getContact().getEmails())
        .isEmpty();
    Email saved = outsiderTeacherManager.addEmail(teacher.getId(), email);

    assertThat(emailRepository.findAll()).hasSize(1);
    assertThat(outsiderTeacherManager.findOneById(teacher.getId()).getContact().getEmails())
        .hasSize(1);
    assertThat(saved.getId()).isNotNull();
  }
  public Email addEmail(Long teacherId, Email model) {
    if (teacherId == null) {
      throw new IllegalArgumentException(
          "Cannot find a " + Teacher.class.getName() + " with a null id.");
    }
    if (model == null) {
      throw new IllegalArgumentException("Cannot persist a null " + Email.class.getName());
    }
    if (model.getId() != null) {
      throw new AlreadyDefinedInOnNonPersistedEntity(
          "Cannot persist a " + Email.class.getName() + " which already has an ID.");
    }

    model = emailManager.create(model);

    Teacher fetched = findOneById(teacherId);
    fetched.getContact().addEmail(model);
    teacherRepository.saveAndFlush(new TeacherDomain(fetched));
    return model;
  }
 @Test(expected = AlreadyDefinedInOnNonPersistedEntity.class)
 public void shouldFailAddEmailWithEmailHavingIdAlreadyDefined() {
   Email model = EmailTest.createOne();
   model.setId(12L);
   outsiderTeacherManager.addEmail(12L, model);
 }