Automated testing is useful, for sure. However, TDD purists tend to focus on one very specific type of testing: automated unit testing, in the small, where you already know the expected output for given input and can easily specify that output using assertions in code. By its nature, TDD emphasises being testable in that specific sense above all else. I don’t think that is necessarily a good thing, partly because that type of universal unit testing may not be a good strategy for every software system, and partly because other useful properties of the code might be diminished because of the changes needed to make it “testable” in the TDD sense.
