#chemfp, the package I develop for #cheminformatics fingerprints, supports the #RDKit, #OpenBabel, #OEChem, and #CDK toolkits. By far the easiest one to test is CDK. It's distributed as a standalone Java jar file, which I access from #Python via the #JPype bridge. From the same environment I can test 12 different CDK versions by simply changing the CLASSPATH. For everything else I need to set up something like nox, and configure the environment. And OEChem is not on PyPI.