"""Hermetic tests for merge approval head pinning (#471)."""
import sys
import unittest
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

from merge_approval_gate import assess_merge_approval_head  # noqa: E402

HEAD_OLD = "8b61c4b41f1b49b271ed3b99657431cf06eeda3e"
HEAD_NEW = "3e4b721d60e97147ba0704773cf57cd0d42cbe31"


class TestMergeApprovalGate(unittest.TestCase):
    def test_fresh_approval_at_current_head(self):
        result = assess_merge_approval_head(
            current_head_sha=HEAD_NEW,
            latest_by_reviewer={
                "reviewer1": {
                    "verdict": "APPROVED",
                    "dismissed": False,
                    "reviewed_head_sha": HEAD_NEW,
                    "submitted_at": "2026-07-06T12:00:00Z",
                }
            },
        )
        self.assertTrue(result["approval_at_current_head"])
        self.assertIsNone(result["stale_approval_block_reason"])

    def test_stale_approval_after_rebase(self):
        result = assess_merge_approval_head(
            current_head_sha=HEAD_NEW,
            latest_by_reviewer={
                "reviewer1": {
                    "verdict": "APPROVED",
                    "dismissed": False,
                    "reviewed_head_sha": HEAD_OLD,
                    "submitted_at": "2026-07-06T10:00:00Z",
                }
            },
        )
        self.assertFalse(result["approval_at_current_head"])
        self.assertEqual(result["latest_approved_head_sha"], HEAD_OLD)
        self.assertIn("stale approval", result["stale_approval_block_reason"])
        self.assertIn(HEAD_OLD, result["stale_approval_block_reason"])
        self.assertIn(HEAD_NEW, result["stale_approval_block_reason"])
        self.assertIn("re-review PR at current head", result["stale_approval_block_reason"])

    def test_no_approval_entries(self):
        result = assess_merge_approval_head(
            current_head_sha=HEAD_NEW,
            latest_by_reviewer={},
        )
        self.assertFalse(result["approval_at_current_head"])
        self.assertIsNone(result["latest_approved_head_sha"])


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