TDD (Test Driven Development) was introduced to me around 2006 with PHPUnit. As a naive, I couldn’t see the benefits, eg., I saw the pattern of code has been updated very often (growing organically) and frequent failing test. I was like, Why should I write unit test to test my own code? with the same data I used for manual testing? As they say I was seeing the forest for the trees. I failed to realize the failing test is actually the benefit of practicing TDD.