Fix Gen Class Without Any Properties

[tamnguyenhuy]

Change fix generate class without Any Properties

syntax = "proto3";

message Hello {
  enum Type {
    UNKNOWN = 0;
    KNOWN = 1;
  }
  message SubHello {
    message HelloExtend {
      optional Type type = 1;
    }
    optional SubHello subHello = 1;
  }
}

Result

package testgen

import kotlinx.serialization.Serializable
import kotlinx.serialization.protobuf.ProtoNumber

@Serializable
public class Hello {
  @Serializable
  public data class SubHello(
    @ProtoNumber(number = 1)
    public var subHello: SubHello? = null,
  ) {
    @Serializable
    public data class HelloExtend(
      @ProtoNumber(number = 1)
      public var type: Type? = null,
    )
  }

  @Serializable
  public enum class Type {
    @ProtoNumber(number = 0)
    UNKNOWN,
    @ProtoNumber(number = 1)
    KNOWN,
  }
}

Fixes #20

[tamnguyenhuy]

@Dogacel please help to take a look at my PR and let me know your thought!!
Thanks

[Dogacel]

Happy to have you as the first contributor 🎉

There are some minor fixes we gotta do. I am not sure if the CI/CD pipeline is ready for PRs as well. I will check it tomorrow morning.

Please let me know if you need any help, I can jump in to fix those small nits 😄

[Dogacel]

Can you run ./gradlew build in your local? I commit all the generated classes under generated-code-tests. Also we should have a test there to verify an empty message without any properties are serialized correctly.

[Dogacel]

One thing I would suggest to simplify the code and reduce duplication is to add this modifier conditionally based on isHasPropertyField call. Simply we can hide this logic behind the generateSingleClass method so users don't have to worry about figuring out which method to call 🙂

[Dogacel]

I have a question, in proto3 if optional int32 x = 1 is considered optional and in proto2 if required int32 x = 1 is considered required, is this going to return false int32 x = 1?

I think we should have a couple of unit tests to verify this doesn't break anything.

[codecov-commenter]

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[Dogacel]

@tamnguyenhuy

I have added some additional checks to make sure we generate the code. Also updated codecov to show coverage info.

I had to merge latest main into your PR to see those. Don't forget to fetch remote 😉