plug request option sends messages to self

[danj3]

During development I optionally add a plug to requests to act as a loopback. The calling process is part of a GenServer. I started seeing spurious messages which I tracked down to happening somewhere in the run_request. The messages are 3-tuples {status, headers, response-body} and probably come from finch since send is plentiful there and none are in req.

Maybe this is a bug, or maybe the plug option isn't supposed (or safe) to be used this way. If it's just unsafe, this might be a warning in the docs. If it is a bug, then I might be able extract a small sample to reproduce. Also, if plug isn't good to use for this, is there an alternative that I missed?

[wojtekmach]

The messages are sent by Plug test adapter that Req uses for this: https://github.com/elixir-plug/plug/blob/v1.15.3/lib/plug/adapters/test/conn.ex#L101.

My suggestion is to use things like Bypass to spawn a server for your test and hit.

I’m gonna close this but please feel free to continue the discussion.

[wojtekmach]

I might be able to consume these messages in Req before returning to the caller as they are never meant to end up in the calling process.

[danj3]

I am injecting the plug not in a proper test, but to simulate the remote during development of other parts, to avoid making remote calls with undesirable side effects, instead of swapping the base url and making a local endpoint. the plug seemed like a simple way to do this, but now i understand that it’s using plug test and that i’m abusing the intended purpose.

of course if you can consume the messages, then i could abuse it this way. thanks for considering the possibility.

[danj3]

changed dep to the 7c04 commit and this problem is resolved. Thank you!