You have a point and automated tests are definitely a big deal. However, as Wikipedia summarizes about "No Silver Bullet":
> "While Brooks insists that there is no one silver bullet, he believes that a series of innovations attacking essential complexity could lead to significant improvements."
So I'd say your experience doesn't contradict his point. Automated testing is not an orders of magnitude improvement, and software projects continue to fail or be flawed at an alarming rate, but it definitely helps! (like Brooks also said of high-level languages).
Automated testing existed at the time Brooks wrote his essay. In "The Soul of a New Machine", published 5 years prior, engineers arrived in the morning and examined the results of the automated tests that ran overnight, looking for regressions and improvements in the microcode for the new processor. The author treats this sort of behavior as standard engineering work, something all serious engineering professionals do and have been doing for as long as such a thing was possible. Not new, not novel.
What we have now is the result of refinements and improvements, perhaps it is a series of innovations. You are right - automated testing doesn't refute Brooks.
> "While Brooks insists that there is no one silver bullet, he believes that a series of innovations attacking essential complexity could lead to significant improvements."
So I'd say your experience doesn't contradict his point. Automated testing is not an orders of magnitude improvement, and software projects continue to fail or be flawed at an alarming rate, but it definitely helps! (like Brooks also said of high-level languages).