They're around. Doctests cover most of the library, many modules have main()s that take care of some more complex unit tests, then the applications that use the

They're around. Doctests cover most of the library, many modules have main()s that take care of some more complex unit tests, then the applications that use the utilities cover a lot of regression cases. Tests are kept as close to the code as possible to keep each module independent and self-explanatory, as explained here: https://boltons.readthedocs.org/en/latest/architecture.html https://boltons.readthedocs.org/en/latest/architecture.html