> the code needs to be tested anyway. If you don't test it, you are just an idiot who has no proof that the code does what it claims to do First, in most cases

> the code needs to be tested anyway. If you don't test it, you are just an idiot who has no proof that the code does what it claims to do First, in most cases you're going to test your code manually anyway- whether you write unit tests or not. So writing unit tests is just in addition to the time already spent testing manually. But most importantly, unit tests often do very little to prove "your code actually does what it claims to do". They prove you have tested some cases, that's all. In many occasions, the code under test doesn't even "claim" to do anything in particular: the claim is that you're delivering a feature, not pieces of code that behave as expected. All your code fragments can behave exactly as expected and still the feature might be broken, or miss implicit requirements, or ill conceived. Finally, unit tests as documentation are disastrous, as they document only details of specific implementations, as opposed to the feature you're expected to deliver. Good comments are a hundred times better that tests in that respect.