You've taken that phrase out of context and as a result missed the point, which was that you need to exercise each line of code many times to have a serious hope of finding all or most of the bugs. Just hitting 100% by creating 1 test case for each branch is almost never sufficient.

When it comes to your argument about external factors, Perl actually has some advantages over more static languages. Need to test rare conditions in a socket connection? Just override the relevant methods of IO::Socket to produce them when you want. The same trick works for lots of things which are otherwise hard to test.

TDD can work for large systems, because what you do is test the hell out of the small pieces, with the same usage patterns as your full application. This doesn't replace large-scale integration testing, but that doesn't mean that you shouldn't do it. I catch lots of stuff in unit tests that don't get caught in our full-system functional tests (and vice versa).

In reply to Re^4: OT: TDD question by kscaldef
in thread OT: TDD question by dragonchild

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