Add checksum verification test

src/tests/test_encryption_checksum.py

@@ -0,0 +1,34 @@
+import re
+import sys
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from cryptography.fernet import Fernet
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from password_manager.encryption import EncryptionManager
+from utils.checksum import verify_and_update_checksum
+
+
+def test_encryption_checksum_workflow():
+    with TemporaryDirectory() as tmpdir:
+        tmp_path = Path(tmpdir)
+        key = Fernet.generate_key()
+        manager = EncryptionManager(key, tmp_path)
+
+        data = {"value": 1}
+        manager.save_json_data(data)
+        manager.update_checksum()
+
+        enc_file = tmp_path / "seedpass_passwords_db.json.enc"
+        chk_file = tmp_path / "seedpass_passwords_db.json_checksum.txt"
+
+        checksum = chk_file.read_text().strip()
+        assert re.fullmatch(r"[0-9a-f]{64}", checksum)
+
+        manager.save_json_data({"value": 2})
+        assert not verify_and_update_checksum(str(enc_file), str(chk_file))
+
+        manager.update_checksum()
+        assert verify_and_update_checksum(str(enc_file), str(chk_file))