Add checksum verification for portable backups

src/tests/test_checksum_utils.py

@@ -1,9 +1,18 @@
 import hashlib
+import json
 from pathlib import Path
 
 from utils import checksum
 
 
+def test_json_checksum():
+    data = {"b": 1, "a": 2}
+    expected = hashlib.sha256(
+        json.dumps(data, sort_keys=True, separators=(",", ":")).encode()
+    ).hexdigest()
+    assert checksum.json_checksum(data) == expected
+
+
 def test_calculate_checksum(tmp_path):
     file = tmp_path / "data.txt"
     content = "hello world"