Unexpected 0-th value enum JSON serialization

The testing message is defined as follows:

syntax = "proto2";

message MessageWithEnum {
    enum EnumType {
      FOO = 0;
      BAR = 1;
    }
    optional EnumType value = 1;
}

We observe the following serialization with pbandk:

Source message	current JSON serialization	expected JSON serialization
MessageWithEnum()	{"value":null}	{}
MessageWithEnum(value=FOO)	{}	{"value":"FOO"}
MessageWithEnum(value=BAR)	{"value":"BAR"}	OK!

The bug is reproduced in a unit test here: https://github.com/streem/pbandk/pull/234

I know that proto2 doesn’t really have a JSON spec defined, but other protobuf implementations (java, python, swift) would all behave as expected in this example.

In proto3, we observed the following serialization behavior:

Source message	current JSON serialization	expected JSON serialization
TestAllTypesProto3()	{}	OK!
TestAllTypesProto3(optionalNestedEnum = FOO)	{}	{"value":"FOO"}
TestAllTypesProto3(optionalNestedEnum = BAR)	{"value":"BAR"}	OK!

1. Do you agree that the current behavior is unexpected?
2. Would you be open for us contributing a fix for it?

Thank you for your time 😃

[garyp]

@antongrbin It’s released now!

[garyp]

@antongrbin Thank you for the thorough fix and tests!