from inventory import Item, low_stock, total_value


def test_total_value_counts_every_unit() -> None:
    items = [Item("bolt", 0.25, 100), Item("nut", 0.10, 40)]
    assert total_value(items) == 29.0


def test_low_stock_is_alphabetical() -> None:
    items = [Item("washer", 0.05, 2), Item("bolt", 0.25, 100), Item("anchor", 3.0, 1)]
    assert low_stock(items) == ["anchor", "washer"]
