verify(map, atLeast(0)).isEmpty();
    verify(map, atLeast(0)).remove(any());
    verify(map, atLeast(0)).size();
    verifyNoMoreInteractions(map);
  }

  public void testStandardKeySet() throws InvocationTargetException {
    @SuppressWarnings("unchecked")
    Map<String, Boolean> map = mock(Map.class);

    Map<String, Boolean> forward =
        new ForwardingMap<String, Boolean>() {