Fix. Mock not working for grandchildren and beyond

[carrascoacd]

Context

!is_nil(Process.get(ancestor, __MODULE__)) always returns true, hence the find fn returns the first ancestor.

Solution

Iterate properly over ancestors trying to find the __MODULE__ key.

cc/ @yordis

[yordis]

🚀

[tomekowal]

Hey! Thanks for that fix. I was bitten by the same issue recently.
However, I am wondering if the code works as intended.
E.g. it starts searching for the mock from the "oldest" or "most root" ancestor.
If, for some reason, parent process defined a mock, then defining new one in the test process would not work.
Also, I don't think $ancestors is the correct thing to use.
E.g. for supervised tasks, the ancestor is the task supervisor and not the test process.

I believe, something like this should work better:

pids = [self() | Enum.reverse(Process.get(:"$callers", []))]

pid_holder = Enum.find(pids, nil, fn pid -> ... end)

If you agree with my reasoning, I am happy to make a PR :)