when(backingMap.get(KEY)).thenReturn(initial);

    assertEquals(INITIAL_COUNT, multiset.add(KEY, COUNT_TO_ADD));
    assertEquals(INITIAL_COUNT + COUNT_TO_ADD, initial.get());
  }

  public void testAdd_laterFewWithOverflow() {
    int INITIAL_COUNT = 92384930;
    int COUNT_TO_ADD = Integer.MAX_VALUE - INITIAL_COUNT + 1;

    when(backingMap.get(KEY)).thenReturn(new AtomicInteger(INITIAL_COUNT));