// we shouldn't see any more map operations; CHM will now just update the AtomicInteger

    assertEquals(12, multiset.add(KEY, 3));
    assertEquals(15, existing.get());
  }

  public void testRemove_zeroFromSome() {
    final int INITIAL_COUNT = 14;
    when(backingMap.get(KEY)).thenReturn(new AtomicInteger(INITIAL_COUNT));

    assertEquals(INITIAL_COUNT, multiset.remove(KEY, 0));
  }

    // we shouldn't see any more map operations; CHM will now just update the AtomicInteger

    assertEquals(12, multiset.add(KEY, 3));
    assertEquals(15, existing.get());
  }

  public void testRemove_zeroFromSome() {
    final int INITIAL_COUNT = 14;
    when(backingMap.get(KEY)).thenReturn(new AtomicInteger(INITIAL_COUNT));

    assertEquals(INITIAL_COUNT, multiset.remove(KEY, 0));
  }