@Test
  public void weightedFriendRecommendation() throws Exception {
    deleteSocialGraph();
    Person a = personRepository.createPerson("a");
    Person b = personRepository.createPerson("b");
    Person c = personRepository.createPerson("c");
    Person d = personRepository.createPerson("d");
    Person e = personRepository.createPerson("e");
    Person f = personRepository.createPerson("f");

    // A is friends with B,C and D
    a.addFriend(b);
    a.addFriend(c);
    a.addFriend(d);

    // E is only friend with B
    e.addFriend(b);

    // F is friend with B, C, D
    f.addFriend(b);
    f.addFriend(c);
    f.addFriend(d);

    ArrayList<Person> recommendations =
        fromIterableToArrayList(a.getFriendRecommendation(2).iterator());

    // Recommend F to A
    assertThat(recommendations.get(0), equalTo(f));
    // Recommend E to A
    assertThat(recommendations.get(1), equalTo(e));
  }
 private static void setupFriendsBetweenPeople(int maxNrOfFriendsEach) {
   for (Person person : personRepository.getAllPersons()) {
     int nrOfFriends = r.nextInt(maxNrOfFriendsEach) + 1;
     for (int j = 0; j < nrOfFriends; j++) {
       person.addFriend(getRandomPerson());
     }
   }
 }
  @Test
  public void singleFriendRecommendation() throws Exception {
    deleteSocialGraph();
    Person a = personRepository.createPerson("a");
    Person b = personRepository.createPerson("b");
    Person c = personRepository.createPerson("c");
    Person d = personRepository.createPerson("d");
    Person e = personRepository.createPerson("e");

    // A is friends with B,C and D
    a.addFriend(b);
    a.addFriend(c);
    a.addFriend(d);

    // E is also friend with B, C and D
    e.addFriend(b);
    e.addFriend(c);
    e.addFriend(d);

    Person recommendation = IteratorUtil.single(a.getFriendRecommendation(1).iterator());

    assertThat(recommendation, equalTo(e));
  }
  @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));
  }
  @Test
  public void getPathBetweenFriends() throws Exception {
    deleteSocialGraph();
    Person start = personRepository.createPerson("start");
    start.setLongTermCtx(LongTermCtxTypes.WORK, "company");
    Person middleMan1 = personRepository.createPerson("middle1");
    middleMan1.setLongTermCtx(LongTermCtxTypes.WORK, "company");
    Person middleMan2 = personRepository.createPerson("middle2");
    middleMan2.setLongTermCtx(LongTermCtxTypes.WORK, "company");
    Person endMan = personRepository.createPerson("endMan");
    endMan.setLongTermCtx(LongTermCtxTypes.WORK, "company");

    // Start -> middleMan1 -> middleMan2 -> endMan

    start.addFriend(middleMan1);
    middleMan1.addFriend(middleMan2);
    middleMan2.addFriend(endMan);

    Iterable<Person> path = start.getShortestPathTo(endMan, 4);

    assertPathIs(path, start, middleMan1, middleMan2, endMan);
    // assertThat( path, matchesPathByProperty(Person.NAME, "start", "middle1", "middle2",
    // "endMan"));
  }