Test-driven development (TDD) is a form of software development where you first write the test, run the test (which would fail first), and then write the minimum code needed to make the test pass. This might sound counter-intuitive. Why do we need to write tests when we know that we have not written any code and we are certain that it will fail because of that?

However, look again. We do eventually write the code that merely satisfies these tests. This means that these tests are not ordinary tests, they are more like specifications. They tell you what to expect. These tests or specifications will directly come from your client's user stories. You are writing just enough code to make it work.

The process of test-driven development has many similarities to the scientific method, which is the basis of modern science. In the scientific method, it is important to frame the hypothesis first, gather data, and then conduct experiments that are repeatable and verifiable to...