Add Req.TransportError and Req.Test.transport_error/2

[wojtekmach]

No description provided.

[wojtekmach]

hey @whatyouhide @josevalim I have a favour ask, what do you think about this API?

I initially thought about returning just an atom:

plug = fn _conn ->
  :econnrefused
end

or to stand out even more from the Plug contract (which obviously does not supports it) maybe throw(:econnrefused) but figured exception is extensible. I hope not but maybe people want to check for Mint.HTTPError, Finch.HTTPError, etc. Which I'm not standardising on btw, meaning, Finch adapter turns Mint.TransportError to Req.TransportError but other ones it might return are returned as is.

Any feedback appreciated!

[whatyouhide]

I like this more than the atom.

[josevalim]

I think this is better than the atom indeed. You could also have some sort of Req.Plug.halt(conn, reason), if you want to keep the Plug contract, and then you store the reason somewhere in the connection.

[whatyouhide]

Oh that's a very good idea, because it allows you to keep the public API flexible!

[wojtekmach]

reason being exception struct or atom and friends?

maybe Req.Test.transport_error(conn, reason)?

[whatyouhide]

Yeah I think Req.Test.transport_error(conn, reason) is the same idea, but it reads better. I also like that it keeps it scoped to Req.Test. reason would be an atom, so that

Req.Test.transport_error(conn, :timeout)

essentially stores conn.private.req_transport_error = %Req.TransportError{reason: :timeout}, which then you can use to return the error. Thoughts?

[whatyouhide]

Beautiful

[wojtekmach]

@whatyouhide @josevalim Thank you!