In a certain way, you always use tests when you are developing something. Write code, run it, see what happens, repeat. The 'see what happens' part is what is

In a certain way, you always use tests when you are developing something. Write code, run it, see what happens, repeat. The 'see what happens' part is what is different in TDD. It can be very similar to what you do without automated testing (while also repeating all previous tests), or it can be a scaffold on endless tests, or two few tests, or anything in between. I've seen too many mocking tests for my taste. In fact, my tests tend to be in the 'integration tests, not unit tests' category.