I realise it is not as easy as just dropping in a protobuf and gRPC library, but given that smocker is written in Go, I think it is in an excellent spot to be able to mock gRPC services too. The only options I know of for this are commercial and (the one I have actually seen) Java based. I think this would be a very attractive feature, especially for people writing Go based services (like we are) which tend to use gRPC over REST a lot.
I realise it is not as easy as just dropping in a protobuf and gRPC library, but given that smocker is written in Go, I think it is in an excellent spot to be able to mock gRPC services too. The only options I know of for this are commercial and (the one I have actually seen) Java based. I think this would be a very attractive feature, especially for people writing Go based services (like we are) which tend to use gRPC over REST a lot.