llm-connect/tests/test_costs.py

import pytest

from llm_connect.costs import CostEstimate, CostModel, estimate_cost
from llm_connect.rates import ModelRate, ModelRateRegistry


def test_known_model_cost_matches_lefevre_smoke_budget():
    estimate = estimate_cost("openai/gpt-4o-mini", 28_000, 7_500)

    assert estimate.cost_source == "rate_table:openai/gpt-4o-mini"
    assert estimate.cost_usd == pytest.approx(0.0087)
    assert estimate.cost_usd == pytest.approx(0.009, rel=0.2)
    assert estimate.cost_eur is not None
    assert estimate.fx_source is not None


def test_unknown_model_returns_unknown_without_zeroing_cost():
    estimate = estimate_cost("unknown/model", 100, 50)

    assert estimate.cost_usd is None
    assert estimate.cost_eur is None
    assert estimate.cost_source == "unknown"


def test_registry_override_controls_estimate():
    registry = ModelRateRegistry(
        {
            "vendor/model": ModelRate(
                "vendor/model",
                prompt_per_1k=1.0,
                completion_per_1k=2.0,
            )
        }
    )

    estimate = estimate_cost("vendor/model", 1_000, 500, registry=registry, fx=1.0)

    assert estimate.cost_usd == pytest.approx(2.0)
    assert estimate.prompt_cost_usd == pytest.approx(1.0)
    assert estimate.completion_cost_usd == pytest.approx(1.0)
    assert estimate.cost_eur == pytest.approx(2.0)


def test_zero_tokens_are_valid_and_cost_zero_for_known_model():
    estimate = CostModel(fx=1.0).estimate_cost("openai/gpt-4o-mini", 0, 0)

    assert estimate.cost_usd == 0
    assert estimate.prompt_cost_usd == 0
    assert estimate.completion_cost_usd == 0
    assert estimate.cost_eur == 0


def test_negative_tokens_are_rejected():
    with pytest.raises(ValueError, match="prompt_tokens"):
        estimate_cost("openai/gpt-4o-mini", -1, 0)


def test_kimi_k3_rate_and_eur_conversion():
    estimate = estimate_cost("moonshotai/kimi-k3", 1_000, 1_000, fx=0.92)

    # $0.003 + $0.015 = $0.018; ×0.92 = €0.01656
    assert estimate.cost_usd == pytest.approx(0.018)
    assert estimate.cost_eur == pytest.approx(0.01656)
    assert estimate.cost_source == "rate_table:moonshotai/kimi-k3"


def test_apply_fx_false_skips_eur():
    estimate = estimate_cost("moonshotai/kimi-k3", 100, 0, apply_fx=False)

    assert estimate.cost_usd is not None
    assert estimate.cost_eur is None
    assert estimate.fx_source is None