@Test
public void testList() {

    List<Item> retrievedItems = Arrays.asList(createItem(new Id(), "item1"), createItem(new Id(), "item2"),
            createItem(new Id(), "item3"));
    Response<List<Item>> itemListResponse = new Response<>(retrievedItems);
    doReturn(itemListResponse).when(stateAdaptorMock).listItems(context);
    Collection<Item> items = itemManagerImpl.list(context);
    Assert.assertEquals(items, retrievedItems);
}