protected void notifyModelChanged(EpoxyModel<?> model) {
    notifyModelChanged(model, null);
  }
@Test
  public void testNotifyModelChanged() {
    TestModel testModel = new TestModel();
    testAdapter.addModels(testModel);
    testAdapter.notifyModelChanged(testModel);
    verify(observer).onItemRangeChanged(0, 1, null);

    checkDifferState();
  }