}

  public void testRemove_zeroFromNone() {
    when(backingMap.get(KEY)).thenReturn(null);

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

  public void testRemove_nonePresent() {
    when(backingMap.get(KEY)).thenReturn(null);

    assertEquals(0, multiset.remove(KEY, 400));
  }

  public void testRemove_someRemaining() {
    int countToRemove = 30;