Rework API

[whatyouhide]

WIP API discussed with @josevalim.

[whatyouhide]

@josevalim you were right, shaved off a lot of code by using your proposed API. One last question from me: do we want to be able to remove ownerships? We could do that by having the callback in get_and_update/4 return nil, which would act as "delete this ownership" if the ownership exists (and no-op if it doesn't exist).

[whatyouhide]

@josevalim this is ready for review. This API is fantastic IMO, and definitely works on Mox 🙃

I have the Mox PR in dashbitco/mox#148.

Right now, we're basically keeping Mox.Server just for the sake of keeping track of whether we're in global mode or private mode. I’m not sure it's worth to extract that part into this lib just yet because I’m not sure we'll need it in other places.

[wojtekmach]

{:ok, {owner_pid, metadata}}

I don't think it's returned anymore and the typespecs say so. Which I think is a shame because we could always find metadata from any caller with just one call instead of now two calls:

defmodule Req.Test do
  @ownership Req.Ownership

  def stub(name) do
    case NimbleOwnership.fetch_owner(@ownership, callers(), name) do
      {:ok, owner} when is_pid(owner) ->
        %{^name => value} = NimbleOwnership.get_owned(@ownership, owner)
        value

      :error ->
        raise "cannot find stub #{inspect(name)} in process #{inspect(self())}"
    end
  end

  def stub(name, value) do
    NimbleOwnership.get_and_update(@ownership, self(), name, fn _ -> {:ok, value} end)
  end

  defp callers do
    [self() | Process.get(:"$callers") || []]
  end
end

I think 2 calls are still OK but thought I'd mention this anyway.

[whatyouhide]

@wojtekmach I lost 90% of context on this already ahah. We could add fetch_owner_with_metadata/3, but do you have time to take a look at whether that's viable and if it would help in Mox too?

[wojtekmach]

Yup I’ll look into it soon!