What the author didn't consider is that test code adds redundancy to the code base - if you introduce a bug only in the test code, while the tested code is corr

What the author didn't consider is that test code adds redundancy to the code base - if you introduce a bug only in the test code, while the tested code is correct, will make the test fail, and you will fix this. Where instead the amount of test code can become a problem, in my experience, is with maintenance. Efficiency is very important.