My experience is that the resulting architecture will sometimes end up with characteristics that makes it easy to test but more complex, exposes things it shoul

My experience is that the resulting architecture will sometimes end up with characteristics that makes it easy to test but more complex, exposes things it should not and too many layers of indirection. DHH wrote some about it here: https://dhh.dk/2014/test-induced-design-damage.html https://dhh.dk/2014/test-induced-design-damage.html I do like automated tests (unit and integration) and often TDD is appropriate. However tests are not the end goal of an architecture. The code should be maintainable, easy to follow and simple to reduce number of bugs. If TDD starts to change that by adding layers of indirection or changing the purpose of something just so you can do a fast unit test then something is wrong.