from __future__ import annotations

from decimal import Decimal

from v1.agent.service import aggregate_session_cost


def test_aggregate_session_cost_sums_non_negative_values() -> None:
    total = aggregate_session_cost([Decimal("0.010000"), Decimal("0.002500")])
    assert total == Decimal("0.012500")


def test_aggregate_session_cost_rejects_negative_value() -> None:
    try:
        aggregate_session_cost([Decimal("-0.010000")])
        raised = False
    except ValueError:
        raised = True

    assert raised is True
