import pytest

from shipping import shipping_cost


def test_small_domestic_order():
    assert shipping_cost(20) == 5


@pytest.mark.parametrize(
    "subtotal, region, expected",
    [
        (0, "domestic", 5),
        (49.99, "domestic", 5),
        (50, "domestic", 0),
        (50.01, "domestic", 0),
        (0, "international", 18),
        (20, "international", 18),
        (49.99, "international", 18),
        (50, "international", 12),
        (50.01, "international", 12),
    ],
)
def test_shipping_rates(subtotal, region, expected):
    assert shipping_cost(subtotal, region) == expected


@pytest.mark.parametrize("region", ["domestic", "international"])
def test_negative_subtotal(region):
    with pytest.raises(ValueError, match="^subtotal must be nonnegative$"):
        shipping_cost(-1, region)


def test_unsupported_region():
    with pytest.raises(ValueError, match="^unsupported region$"):
        shipping_cost(10, "unknown")