@Test public void removingOneFriendIsHandledCleanly() { Person person1 = personRepository.getPersonByName("person#1"); Person person2 = personRepository.getPersonByName("person#2"); person1.addFriend(person2); int noOfFriends = person1.getNrOfFriends(); person1.removeFriend(person2); int noOfFriendsAfterChange = person1.getNrOfFriends(); assertThat(noOfFriends, equalTo(noOfFriendsAfterChange + 1)); }