Simplify shelve error message on validation of serialization

Author: furkanonder

Lib/shelve.py

@@ -114,9 +114,7 @@ def _validate_serialized_value(serialized_value, original_value):
                 invalid_type = "None"
             else:
                 invalid_type = type(serialized_value).__name__
-            msg = (f"Serializer returned {serialized_value!r} for value "
-                   f"{original_value!r}, but database values must be "
-                   f"bytes or str, not {invalid_type}")
+            msg = f"Serializer must return bytes or str, not {invalid_type}"
             raise ShelveError(msg)
 
     def __iter__(self):

Lib/test/test_shelve.py

@@ -468,16 +468,14 @@ def deserializer(data):
                              deserializer=deserializer) as s:
                 with self.assertRaises(shelve.ShelveError) as cm:
                     s["key"] = "value"
-                self.assertEqual("Serializer returned None for value 'value', but "
-                                 "database values must be bytes or str, not None",
+                self.assertEqual("Serializer must return bytes or str, not None",
                                  f"{cm.exception}")
 
             with shelve.open(self.fname, serializer=int_serializer,
                              deserializer=deserializer,) as s:
                 with self.assertRaises(shelve.ShelveError) as cm:
                     s["key"] = "value"
-                self.assertEqual("Serializer returned 3 for value 'value', but "
-                                 "database values must be bytes or str, not int",
+                self.assertEqual("Serializer must return bytes or str, not int",
                                  f"{cm.exception}")
 
     def test_shelve_type_compatibility(self):