Coverage data for individual test suites is mangled when running multiple test suites

[ElectronicRU]

Current behaviour

When using several testing frameworks (the case at least with EUnit, Common Test, and PropEr) with rebar3, the total coverage data is calculated right, but per-method (?) coverage shown is actually + <that method's coverage>.

Expected behaviour

All coverages are calculated correctly.

Proof of concept

https://bitbucket.org/0player/cover_test

[ferd]

Sounds like a variation of what was fixed by merging #1316.

This means that while rebar3 do ct -c, eunit -c, proper -c, cover works fine, running them individually in a sequence still shows the problem.

[ferd]

Fun fact: running the following also causes the issue:

$ rebar3 do ct -c, eunit -c, proper -c
$ rebar3 cover

I'm guessing something funny happens with a freshly started cover server that does not happen with a previously running one, despite the following procedure to load cover data being fully identical in all cases.

rebar3 do eunit -c, ct -c && rebar3 do proper -c, cover also works fine. Starting to wonder if there's something in cover compilation that primes the cover pid properly and doesn't happen on a single cover run.

[ElectronicRU]

Turns out to load coverdata properly, you need to have relevant modules cover-compiled. Forcing a cover compilation on rebar3 cover does fix the problem.