What if a providers grpc handler calls another grpc method (provider is a consumer here e.g crypt service). How can I test provider in that case. Right now I have it mocked but it does not work.

The failure seems to be because your code is not calling the downstream service, which is currently mocked. I can't say much more because I don't know your code, but mocking/stubbing is totally reasonable here and is what I'd recommend