def test_replacing_item_preserves_order(self):
item_list = IdList()
item1 = Item('id1')
item2 = Item('id2')
item3 = Item('id3')
item4 = Item('id4')
item_list.add(item1)
item_list.add(item2)
item_list.add(item3)
item_list.replace('id2', item4)
assert item_list.items == [item1, item4, item3]
def test_replace_not_present_item_raises_exception(self):
item_list = IdList()
with pytest.raises(KeyError):
item_list.replace('id_doesnt_exist', Item('id1'))