As developers, we always write code targeted to achieve a certain feature/functionality. The piece of code is written down with best efforts to be bug free and to work exactly as expected. Unfortunately we human beings are prone to make errors & mistakes, as a result bugs do creep in. Hence it is always advisable to test out individual units of code, in order to be sure enough that your implementation actually works. With this we are introduced to the term “Unit Testing”. We can define unit testing in this manner:
It is the methodology of testing out individual units of behaviour. An individual unit of behaviour is the smallest possible unit of behaviour that can be individually tested in isolation.