Code coverage of a pybind11 library

[hman523]

Hi all! I am trying to determine if I am testing all of the functions within a python module made using pybind. I have tried using coverage.py but it only showed the functions written 100% in python. I also tried gcov but it did not really show anything meaningful. I would like to just see what functions from the module are called when running pytest. Has anyone done this before?

[jpreiss]

Did you ever find a good solution?

[ianthomas23]

contourpy generates coverage information for both Python and pybind11-wrapped C++ in this workflow: https://github.com/contourpy/contourpy/blob/main/.github/workflows/test.yml (see the "Test debug with coverage" run). Log file for the latest run is at https://github.com/contourpy/contourpy/actions/runs/6220269820/job/16879953676 and it uploads to https://app.codecov.io/gh/contourpy/contourpy.

Essentially you need to

• Pass appropriate compile and link flags
• Use appropriate flags when running pytest
• Extract and combine the Python and C++ coverage information

If you want to do this locally rather than upload to codecov then you need to do something like

cat coverage.lcov coverage.cpp > coverage.combined
lcov --list coverage.combined

to get textual output or

genhtml coverage.combined --output-directory out

to generate HTML output.

Note this is using meson-python as the build backend. If you are using a different build backend you will no doubt need different compile/link flags.

[jpreiss]

@ianthomas23 thank you for the suggestions!!