Cython support

Feature Request:

I’m working on a Python3.5 project which uses Cython v0.23.4 for several modules via the pyximport method. We’re using pytest 3.1.3 and pytest-cov 2.5.1. Currently pytest-cov only reports on .py files. Our tests are written with the convention of test_.py and within those, calls to “def” functions and methods within *.pyx files are made in order to test the output (inside of our *.pyx modules we have a “def” signature for every “cdef” implementation so that non-cython modules in our application can easily call cythonized code in pure python).

Example:

cdef int _return_pos_int():
    return 1

def return_pos_int():
    return _return_pos_int()

If we were testing the example above, our tests would call the function with the “def return_pos_int()” signature.

The current pytest-cov output ignores covered .pyx files, even if there are .py tests accessing those modules. Ideally, pytest-cov would be able to determine the coverage for cython .pyx modules as it does with normal .py modules.

[ionelmc]

I’m trying this now, these changes seem to make it work.

Two things to consider:

• setting the CYTHON_TRACE=1 macro ain’t enough, you also need to litter all your pyx files with # cython: linetrace=True pragmas.
• you need to compile inplace (eg: python setup.py clean --all build_ext --force --inplace if your using the cython support in setuptools)

@darthlukan Your coverage report looks weird. Why do you have a bare __init__.py there? Where are the .so files being built/installed?

Also, try removing source filters (just use a bare --cov till you see hits on pyx files).

[ionelmc]

@darthlukan where are the .so files located then? if in the same place as the .pyx files then probably you’re only missing the macro definitions, eg:

from os import environ
environ['CFLAGS'] = '-DCYTHON_TRACE=1'
import pyximport
pyximport.install()