feat: require approval at current PR head for merge (#471)

Add merge_approval_gate assessment so gitea_merge_pr fails closed when visible APPROVED reviews do not pin the live head SHA. Expose approval_at_current_head and stale_approval_block_reason in review feedback. Document re-review requirement in canonical merge workflow. Closes #471. Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
2026-07-08 00:37:54 -04:00
parent a1de4ab8f9
commit 89582a0f2a
7 changed files with 184 additions and 1 deletions
@@ -0,0 +1,59 @@
+"""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()