"""Offline checks that reruns cannot overwrite archived evidence."""
from pathlib import Path
import tempfile
import unittest
from unittest.mock import patch

from reproduce import Experiment


class OutputGuardTests(unittest.TestCase):
    def test_nonempty_output_is_rejected_before_any_work(self):
        with tempfile.TemporaryDirectory(prefix="asn-real-mcp-guard-", dir="/private/tmp") as temp:
            base = Path(temp)
            output = base / "evidence"
            output.mkdir()
            sentinel = output / "validation.json"
            original = '{"status":"previous-run"}\n'
            sentinel.write_text(original)
            root = base / "new-run"
            with patch("reproduce.subprocess.run") as process, \
                    patch("reproduce.urllib.request.urlopen") as download:
                with self.assertRaisesRegex(FileExistsError, "Refusing to overwrite evidence"):
                    Experiment(root, output)
                process.assert_not_called()
                download.assert_not_called()
            self.assertFalse(root.exists())
            self.assertEqual(sentinel.read_text(), original)
            self.assertEqual(list(output.iterdir()), [sentinel])

    def test_fresh_empty_output_remains_compatible(self):
        with tempfile.TemporaryDirectory(prefix="asn-real-mcp-guard-", dir="/private/tmp") as temp:
            base = Path(temp)
            output = base / "evidence"
            output.mkdir()
            with patch.object(Experiment, "run", return_value="") as process:
                experiment = Experiment(base / "new-run", output)
            self.assertEqual(experiment.output, output.resolve())
            process.assert_called_once()
            self.assertEqual(process.call_args.args[0][:3], ["git", "init", "--initial-branch=main"])
            self.assertEqual(list(output.iterdir()), [])


if __name__ == "__main__":
    unittest.main()