@Test
  public void validateGender() {
    when(person.getGender()).thenReturn(null);

    exception.expect(GenderNotProvidedException.class);

    subject.execute(person);
  }
 private void configurePerson() {
   when(person.getName()).thenReturn("Person Name");
   when(person.getGender()).thenReturn(Gender.M);
   when(person.getContact()).thenReturn(contact);
 }