[erlang-bugs] Eunit, test generators and code:purge()

[Andrew Thompson]

So, I've been chasing a failure in a test suite for the last couple
days. Turns out, the problem is the test suite does this:

* Test module A, with a test generator function
* Test module B, and meck module A

Eunit's runner is holding a reference to something in module A (probably
a fun), so when meck does a purge on A as part of test B, the code
server kills the eunit test runner process. This bug was actually
reported three years ago:

http://erlang.org/pipermail/erlang-bugs/2010-June/001844.html

But it still affects at least R15B03, which is what I'm using.

I have a slightly modified version of b_mod that proves that eunit is
holding a ref to something from a_mod:

-module(b_mod).

-include_lib("eunit/include/eunit.hrl").

second_test() ->
    ?debugFmt("I am ~p ~p~n", [self(), erlang:process_info(self())]),
    true = code:delete(a_mod),
    ?debugFmt("processes using a_mod: ~p~n", [[P || P <- processes(), erlang:check_process_code(P, a_mod)]]),
    true = code:soft_purge(a_mod),
    ok.


I looked into trying to patch this, but the eunit code is too convoluted
for me to understand where it is holding the problematic reference.

Andrew