Thanks for making the test case and PR!! This is just a cursory review. I won't have time for a thorough review prior to 3.7.0b1 and someone else should review it, too, particular @doko42. Comments: The test in the PR fails as it stands; see the Travis CI output. The test_support module is there to test things in the test support module; this new test case does not belong there (though I'm not sure where, it might need a new file?). The test fails if run from an installed Python rather than from a build directory: the base_dir path calculation needs to handle both cases, see other tests for examples. (You can test an installed Python by using something like ./configure --prefix=/tmp/pybin; make ...; make install; cd /out/of/the/build/directory ; /tmp/pybin/python3 -m test ... ) Building of all of those modules will be problematic because some depend on compiling and linking with third-party libraries which may not be present or whose paths are platform dependent. So perhaps simplify the list of modules to those without external dependencies.