Unit tests are often overlooked in the software development process but there are a lot of nice side effects of writing unit tests. After writing production software code for more than a decade, which has served billions of users for planet scale applications, I can confidently say that unit tests hold a critical place in software development lifecycle.
Despite the importance of unit tests, many engineers often overlook them due to timeline constraints or their over reliance on manual testing. There is also a misconception that unit tests slow down software development which is not necessarily true. As a matter of fact, study reveals that test driven development (TDD) may have a positive impact on software development productivity. In the long run, unit tests make iterating on code easier and faster.