"""Tests for the separate line/branch coverage policy gate."""

from __future__ import annotations

import importlib.util
from pathlib import Path


SCRIPT = Path(__file__).parents[1] / "scripts" / "check_coverage_thresholds.py"
SPEC = importlib.util.spec_from_file_location("check_coverage_thresholds", SCRIPT)
assert SPEC is not None and SPEC.loader is not None
MODULE = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(MODULE)


def _report(line: float = 49.0, branch: float = 36.0) -> dict[str, object]:
    return {
        "totals": {
            "percent_statements_covered": line,
            "percent_branches_covered": branch,
        },
    }


def test_validate_coverage_accepts_exact_floors():
    assert MODULE.validate_coverage(
        _report(), min_line=49.0, min_branch=36.0,
    ) == []


def test_validate_coverage_reports_each_regression():
    failures = MODULE.validate_coverage(
        _report(line=48.9, branch=35.9), min_line=49.0, min_branch=36.0,
    )

    assert failures == [
        "line coverage 48.90% is below the 49.00% floor",
        "branch coverage 35.90% is below the 36.00% floor",
    ]


def test_validate_coverage_rejects_malformed_totals():
    assert MODULE.validate_coverage(
        {}, min_line=49.0, min_branch=36.0,
    ) == ["coverage report is missing the totals object"]


def test_validate_coverage_rejects_non_numeric_metrics():
    report = _report()
    report["totals"]["percent_statements_covered"] = True
    report["totals"]["percent_branches_covered"] = float("nan")

    assert MODULE.validate_coverage(
        report, min_line=49.0, min_branch=36.0,
    ) == [
        "coverage report is missing numeric percent_statements_covered",
        "coverage report is missing numeric percent_branches_covered",
    ]