Add test that fails for Datum type

Author: nielstron

test/pycardano/test_serialization.py

@@ -1,4 +1,6 @@
 from dataclasses import dataclass, field
+
+from pycardano import Datum
 from test.pycardano.util import check_two_way_cbor
 from typing import Any, Dict, List, Optional, Set, Tuple, Union
 
@@ -173,6 +175,15 @@ class Test1(MapCBORSerializable):
 
     check_two_way_cbor(t)
 
+def test_datum_type():
+    @dataclass
+    class Test1(MapCBORSerializable):
+        b: Datum
+
+    t = Test1(b=1)
+
+    check_two_way_cbor(t)
+
 
 def test_wrong_primitive_type():
     @dataclass