from __future__ import annotations

from datetime import timedelta
from pathlib import Path
from unittest.mock import patch

import pytest
from backup_tool.gc import purge_repository


def test_gc_keeps_manifest_when_unlink_fails(tmp_path: Path) -> None:
    root = tmp_path / "repository"
    manifest = root / "manifests" / "deleted.json"
    manifest.parent.mkdir(parents=True)
    manifest.write_text('{"entries": []}', encoding="utf-8")

    with (
        patch("pathlib.Path.unlink", side_effect=OSError("read-only")),
        pytest.raises(OSError),
    ):
        purge_repository(root, {"deleted"}, grace=timedelta(0))

    assert manifest.exists()