def test_update_stock(inventory_fixture, ingredient_cost_fixture): system1 = System(inventory_fixture, ingredient_cost_fixture) orig_white_buns = system1.Inventory["white"] system1.Update_Stock("white", 5) assert (system1._Inventory["white"] == (orig_white_buns + 5)) system1.Update_Stock("white", -10) assert (system1._Inventory["white"] == (orig_white_buns - 5))