tests: add an encoding roundtrip for Struct

src/betterproto/__init__.py

@@ -55,7 +55,6 @@
     hybridmethod,
 )
 
-
 if TYPE_CHECKING:
     from _typeshed import (
         SupportsRead,

tests/test_struct.py

@@ -17,6 +17,11 @@ def test_struct_roundtrip():
     assert struct_from_dict.to_dict() == data
     assert struct_from_dict.to_json() == data_json
 
+    struct_from_proto = Struct().parse(bytes(struct_from_dict))
+    assert struct_from_proto.fields == data
+    assert struct_from_proto.to_dict() == data
+    assert struct_from_proto.to_json() == data_json
+
     struct_from_json = Struct().from_json(data_json)
     assert struct_from_json.fields == data
     assert struct_from_json.to_dict() == data