I would rather at least put the "generic" test dependencies into an extras_require. Would probably also just get rid of the dependency on pytest-timeout (which was the cause of some recent changes) as in our case it's just a matter of calling faulthandler.dump_traceback_later(300, exit=False) which can easily be done in a local plugin.
(I don't feel that strongly about it, but I never really liked requirement files and feel that extra requires are better suited; for example, the latter are directly accessible by pip through PyPI, but not the former.)

👍 in principle. I like that you can now install the dependencies locally with out having to read the travis flie.

Lets punt on mucking with setup.py for now.

Thanks @dstansby ! That's going to help maintainability.