Behaviour for mock GRPC.Adapter.Gun

It looks like that library doesn’t define a @behaviour for the gun client so you’ll have to derive it yourself. Based on what I see in lib/grpc/stub.ex, you’ll probably need to write callbacks for these functions:

• connect/2
• disconnect/1
• send_request/3
• send_headers/2
• end_stream/1
• cancel/2
• recv_headers/3
• recv_data_or_trailers/3

If you write up some nice callbacks for these functions I’m sure the library maintainer(s) would appreciate a PR to add it to the project!

Thanks @the-mikedavis,

I already tried to extract the @behaviour from the module public functions, some of them have @spec’s while others don’t, and I have to figure out the correct @spec for those, hence the question

ah yep you’ll have to infer the types for ones that are missing

I think this is generally considered bad… behaviour (haha) but you can always use the any() type when in doubt:

# test/support/my_grpc_gun_adapter_behaviour.ex
defmodule MyGrpcGunAdapterBehaviour do
  @callback connect(GRPC.Channel.t(), any()) :: {:ok, GRPC.Channel.t()} | {:error, any()}
  @callback disconnect(any()) :: any()
  # ..
end

Mox.defmock(MyGrpcGunAdapterMock, for: MyGrpcGunAdapterBehaviour)

since Mox doesn’t check the types of the callbacks (although hammox does that if you’re interested in that kind of rigor)