I've been in several multi-million line codebases that all were built with TDD. It's possible. The default way of organizing code with DI makes unit tests extr

I've been in several multi-million line codebases that all were built with TDD. It's possible. The default way of organizing code with DI makes unit tests extremely expensive to write and maintain. Mocks should be banned if you want to add unit tests or practice TDD. Instead the tested code should be pure. Pure code is easy to test, even if it's calling a dozen helper functions.