"Human testing doesn't scale"? Maybe I should have linked to another of his slide presentations that has more background info than practical code.
But for me, from experience, leaving smoke running hourly as a cronjob (that emails me if there's errors) when I'm developing has saved me a pile of debugging. Quite a few times, I've assumed something, only to find that that assumption broke another assumption elsewhere in the code.
I know I'm far too lazy to manually test every time I add new functionality or optimizations, so knowing that I'm going to get an email if there's either something wrong with my code - or that a test is wrong because functionality has changed - is invaluable.
But, if it's just you on the code and it's never going to grow to become a monster(say 10,000 lines or more), then you might not reap the full benefits, or think it's worthwhile. On the other hand, you might be pleasantly surprised at how much it can help :)
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