Re^2: how to begin with testing?

[JadeNB]

While your advice for when to write tests seems spot on—before writing (much) code, and when bugs are found—your advice for when not to write them seems suspect. Even when a complete, working application is in place, it's appropriate to buttress it with tests—they will help with maintenance, so that changes can be seen not to break existing behaviour, and, well, testing, perhaps revealing that an application that seemed to be both complete and working is neither. Since writing tests, especially in Perl, can be very cheap, and need not be done all at once, it seems harmless at worst.

[zwon]

Ok, maybe I made this too categorical. Of course tests would be useful on any stage of program life cycle. I just think that price-usefulness ratio would be too hight to develop complete test suite after program is ready. You saying that writing tests very cheap, hmm, for me its usually more than half of the time I work on a program, so I'd say it rather expensive.

What about maintenance -- yes, I would write tests when I have to maintain program without tests, but again that would be individual tests, not a complete test suite, nobody would pay me for that. The only case I would write full tests is if I'm going to seriously refactor some old stuff; but I would do it just before refactoring and not just after writing a program, because I don't know what requirements would be, if at all.