My counterpoint to this would be that everything you need for proper testing exists already in Julia. Also I would argue that Julia is a much easier language t

My counterpoint to this would be that everything you need for proper testing exists already in Julia. Also I would argue that Julia is a much easier language to write correct code in than Python. Python suffers the general OOP problem where it becomes hard to isolate problems due to all the mutations (imperative coding). While Julia is not a purely functional language, you program in a far more functional style in Julia because it supports it much better. My own experience when working with both languages suggest that I am able to write more pure functions in Julia than Python. I am able to crank out small isolated functions which I quickly test in my REPL environment as I go. It is a different way of working. My Python friends write more formalized tests than me as they code. Julia is perhaps more in the LISP tradition. You are continuously writing and testing as you go in the REPL. Some of those test make their way into my test suite but not all. Because we are generally not writing Server code in Julia testing is less important. If the program crashes so what? What is important is correctness of numerical output. Yes you need tests for that. But I would speculate that tests needed to verify correctness of numerical calculations are less than tests needed to secure uptime for some server service.