Hook up Codecov for coverage reporting on C code

[brettcannon]

See https://github.com/brettcannon/cpython-ci-test/blob/master/codecov.yml for an initial configuration (only differs from the default thanks to the new config for comments).

[tiran]

I have been running lcov regularly. gcov / lcov coverage of C code is a bit tricky for some modules. Some tests require a real terminal (ncurses), X server (tkinter, idle), root privileges (spwd) or special system configuration (yp for nis). The make coverage-lcov target ignores coverage of 3rd party code, too.

 @ # remove 3rd party modules, system headers and internal files with
 @ # debug, test or dummy functions.
 @lcov --remove $(COVERAGE_INFO) \
 '*/Modules/_blake2/impl/*' \
 '*/Modules/_ctypes/libffi*/*' \
 '*/Modules/_decimal/libmpdec/*' \
 '*/Modules/_sha3/kcp/*' \
 '*/Modules/expat/*' \
 '*/Modules/zlib/*' \
 '*/Include/*' \
 '*/Modules/xx*.c' \
 '*/Parser/listnode.c' \
 '*/Python/pyfpe.c' \
 '*/Python/pystrcmp.c' \
 '/usr/include/*' \
 '/usr/local/include/*' \
 '/usr/lib/gcc/*' \
 --output-file $(COVERAGE_INFO)

[brettcannon]

Would we run lcov as a separate coverage step from coverage.py? Or somehow run them simultaneously? I don't know what kind of slowdown we're looking at here if we had both on and if we might run afoul of Travis' free tier limitations.

[tiran]

On my machine it takes almost 10 minutes to run Python's test suite with a gcov instrumented build of Python. My laptop is pretty fast (8 cores i7-4900MQ CPU @ 2.80GHz, 16 GB RAM). I'm able to utilze all cores with 10 parallel test process. It's going to be hard enough to get lcov finish on Travis without coverage.py.

$ make coverage
$ time make test
...
real 9m40.226s
user 56m49.298s
sys 1m17.350s

[brettcannon]

OK, then we can look at running it as a separate test. If you want to try and get this working now then send a PR at https://github.com/brettcannon/cpython-ci-test as that's where I plan to pull the initial config files for Travis and Codecov.

[tiran]

I have to look into it. I'd like to use a service that can use lcov database so we can re-use out-of-tree build and lcov excludes from make coverage-lcov.

[brettcannon]

It looks like lcov is supported by Codecov: https://github.com/codecov/codecov-bash/blob/master/codecov#L822

[brettcannon]

Did you want me to leave this open for you, @tiran to look into lcov?

[abalkin]

Please take a look at https://github.com/abalkin/cpython/tree/ci or specifically at https://codecov.io/gh/abalkin/cpython/branch/ci. @brettcannon is that the "appropriate merging" that you are looking for?

[brettcannon]

@abalkin unfortunately no as there's no coverage for the Lib/ directory. If you include coverage runs for both lcov and coverage.py do the results show up in Codecov as if they were run together?

[abalkin]

Right. I thought I've seen both, but clearly my focus was on C coverage.

We are evaluating codecov's commercial offering in my firm at the moment, so I should have a working setup "soon".

[brettcannon]

Tweaked the title in hopes that someone is able to look into getting C code coverage working.