fire-planner/tests/test_col.py

"""Tests for the COL module — baseline lookup + ratio + simulator wiring."""
from __future__ import annotations

from decimal import Decimal

import pytest

from fire_planner.col import (
    JURISDICTION_REPRESENTATIVE_CITY,
    compute_col_ratio,
    lookup_city,
    representative_city_for,
)
from fire_planner.col.baseline import BASELINES
from fire_planner.col.models import CityCostIndex


class TestBaselineCoverage:
    """Every jurisdiction with a representative city must have a baseline."""

    def test_all_representative_cities_have_baselines(self) -> None:
        missing = [
            city for city in JURISDICTION_REPRESENTATIVE_CITY.values() if city not in BASELINES
        ]
        assert missing == [], (
            f"jurisdiction map points at city(s) without baselines: {missing}"
        )

    def test_baselines_have_positive_totals(self) -> None:
        for slug, idx in BASELINES.items():
            assert idx.total_single_no_rent_gbp > 0, f"{slug} no_rent must be positive"
            assert idx.total_single_with_rent_gbp > idx.total_single_no_rent_gbp, (
                f"{slug} with_rent must exceed no_rent — rent should be a positive add"
            )

    def test_baseline_source_provenance_present(self) -> None:
        for slug, idx in BASELINES.items():
            assert idx.source.name in {"numbeo", "expatistan", "baseline", "manual"}
            assert idx.source.url is not None, f"{slug} baseline missing source URL"
            assert idx.source.url.startswith("https://"), f"{slug} URL must be https"


class TestLookup:
    def test_lookup_known_city(self) -> None:
        london = lookup_city("london")
        assert isinstance(london, CityCostIndex)
        assert london.city == "London"
        assert london.country == "United Kingdom"

    def test_lookup_normalises_input(self) -> None:
        # mixed case, spaces → slug
        assert lookup_city("Kuala Lumpur").city == "Kuala Lumpur"
        assert lookup_city("  Bangkok  ").city == "Bangkok"

    def test_lookup_unknown_raises(self) -> None:
        with pytest.raises(KeyError, match="No COL baseline"):
            lookup_city("atlantis")


class TestColRatio:
    def test_identity_returns_one(self) -> None:
        assert compute_col_ratio("london", "london") == Decimal("1")

    def test_sofia_cheaper_than_london(self) -> None:
        ratio = compute_col_ratio("london", "sofia")
        assert ratio < Decimal("1"), "Sofia must be cheaper than London"
        assert ratio > Decimal("0.2"), "Sofia ratio looks implausibly low"
        # Real Numbeo number is ~0.41
        assert Decimal("0.35") < ratio < Decimal("0.50")

    def test_dubai_cheaper_than_london(self) -> None:
        # Dubai is *cheaper* than London on Numbeo's headline because
        # London rent dominates. This was a surprise — flag it in the
        # baseline note for future-us.
        ratio = compute_col_ratio("london", "dubai")
        assert ratio < Decimal("1")
        assert Decimal("0.70") < ratio < Decimal("0.95")

    def test_bangkok_far_cheaper_than_london(self) -> None:
        ratio = compute_col_ratio("london", "bangkok")
        assert ratio < Decimal("0.40")

    def test_inverse_consistency(self) -> None:
        # If london→sofia is X, sofia→london should be ~1/X within rounding.
        l2s = compute_col_ratio("london", "sofia")
        s2l = compute_col_ratio("sofia", "london")
        assert abs(l2s * s2l - Decimal("1")) < Decimal("0.001")


class TestRepresentativeCity:
    def test_known_jurisdictions(self) -> None:
        assert representative_city_for("uk") == "london"
        assert representative_city_for("cyprus") == "limassol"
        assert representative_city_for("bulgaria") == "sofia"
        assert representative_city_for("uae") == "dubai"
        assert representative_city_for("malaysia") == "kuala-lumpur"
        assert representative_city_for("thailand") == "bangkok"

    def test_nomad_returns_none(self) -> None:
        # Nomad mode is COL-invariant by design — auto-adjust skipped.
        assert representative_city_for("nomad") is None

    def test_unknown_returns_none(self) -> None:
        assert representative_city_for("vulcan") is None