### Question:
ListAdapterHelper { @SuppressWarnings("WeakerAccess") public int getItemCount() { return mList == null ? 0 : mList.size(); } @SuppressWarnings("WeakerAccess")  ListAdapterHelper(ListUpdateCallback listUpdateCallback,
            ListAdapterConfig<T> config); @SuppressWarnings("WeakerAccess") T getItem(int index); @SuppressWarnings("WeakerAccess") int getItemCount(); @SuppressWarnings("WeakerAccess") void setList(final List<T> newList);  }### Answer:
@Test public void initialState() { ListUpdateCallback callback = mock(ListUpdateCallback.class); ListAdapterHelper<String> helper = createHelper(callback, STRING_DIFF_CALLBACK); assertEquals(0, helper.getItemCount()); verifyZeroInteractions(callback); }