int INITIAL_COUNT = 32;

    when(backingMap.get(KEY)).thenReturn(new AtomicInteger(INITIAL_COUNT));
    assertEquals(INITIAL_COUNT, multiset.add(KEY, 0));
  }

  public void testAdd_firstFewWithSuccess() {
    int COUNT = 400;

    when(backingMap.get(KEY)).thenReturn(null);
    when(backingMap.putIfAbsent(eq(KEY), isA(AtomicInteger.class))).thenReturn(null);