Personal opinion here: I don’t think that code inspection and automated tests are mutually exclusive. We write automated tests primarily to reduce the cost of change, not so much to assert correctness.
One cannot really assert correctness with unit tests: as the creator of some code, if you knew that something was incorrect, you would just fix it, and if you don’t know that there is a bug lurking, you cannot write a test for it. We write tests to make sure that our code still does what it is meant to do in face of change. In other words, we write tests for our colleagues (or our future self) that will change our code in the future, so that they can do so knowing if/what they break. A well-tested project is easier to evolve.
Correctness can be inferred by manual tests and code inspections, better if by someone else than the code author. Code reviews and manual tests are about assuring quality.
I think the article is conflating these two aspect, and therefore sees a dichotomy where there is none.
I personally consider writing tests a worth investment of time, and one of the most valuable skills in coding. I also think that code reviews and a good quality assurance process are necessary.
