Hi Lars-Dominik, Lars-Dominik Braun writes: > Adds a new phase validating usalibity of installed Python packages. > > * guix/build/python-build-system.scm (validate-script): Add script. > (validate-loadable): New phase. > (%standard-phases): Use it. > * tests/builders.scm (make-python-dummy): Add test package generator. > (check-build-{success,failure}): Add build helper functions. > (python-dummy-*): Add test packages. > ("python-build-system: &"): Add tests. Attached is a small rework of your original patch. I've made the Python script standalone, which should make it easier to maintain. I've also refactored the tests somewhat and added your copyright information. Is this OK with you? Thanks! Maxim