Verify changing WebDAV hash metadata without rejecting unchanged files

tests/test_backup.py

@@ -159,6 +159,22 @@ class BackupTests(unittest.TestCase):
         with self.assertRaisesRegex(m.BackupError, 'hash mismatch'):
             self.runner.verify_local_hashes(manifest)
 
+    def test_disappearing_hash_requires_download_comparison(self):
+        before = {'file': {'size': 10, 'mtime': 'now', 'hashes': {'SHA-1': 'abc'}}}
+        after = {'file': {'size': 10, 'mtime': 'now', 'hashes': {}}}
+        with patch.object(self.runner, 'verify_local_hashes') as local, \
+                patch.object(self.runner, 'cloud') as cloud:
+            self.runner.validate_final_inventory(before, after)
+            local.assert_called_once_with(after)
+            self.assertIn('--download', cloud.call_args.args)
+
+    def test_new_hash_with_wrong_contents_is_rejected(self):
+        before = {'file': {'size': 10, 'mtime': 'now', 'hashes': {}}}
+        after = {'file': {'size': 10, 'mtime': 'now', 'hashes': {'SHA-1': 'abc'}}}
+        with patch.object(self.runner, 'verify_local_hashes', side_effect=m.BackupError('hash mismatch')):
+            with self.assertRaises(m.BackupError):
+                self.runner.validate_final_inventory(before, after)
+
     def test_pending_maintenance_survives_interrupted_attempt_record(self):
         import time
         self.runner.success = {'completed_at': time.time(), 'maintenance_pending': True}