protected void removeAllModels() {
    int numModelsRemoved = models.size();

    pauseModelListNotifications();
    models.clear();
    resumeModelListNotifications();

    notifyItemRangeRemoved(0, numModelsRemoved);
  }
@Test
  public void testRemoveAllModels() {
    for (int i = 0; i < 10; i++) {
      TestModel model = new TestModel();
      testAdapter.addModels(model);
    }

    testAdapter.removeAllModels();
    verify(observer).onItemRangeRemoved(0, 10);
    assertEquals(0, testAdapter.models.size());

    checkDifferState();
  }