Question

"Refactoring and unit testing are interdependent practices that are vital to the creation and maintenance of adaptive code." Provide an explanation supported with examples (business or code). Be as specific as possible and provide details.

Answer 1

Test-driven development (TDD), is an new age evolutionary approach to development which emphasizes test-first development. Here you write a test before you write just enough production code to fulfill that test and then go on to refactor the production code. The primary goal of TDD is specification and not validation. In other words, it’s one way to think through your requirements or design before your write your functional code (implying that TDD is both an important agile requirements and agile design technique). Another view is that TDD is a programming technique.

Following the TDD process, a developer must focus on the test cases before actually coding anything. That meansa developer is thinking more about the use of the software and the design of user interfaces to achieve that. As a result, the developer is more interested in the interface than in the implementation—and that leads to more usable software.

There are several other tangible benefits for taking a TDD approach, including:

• Creating a metric for the code quality that can be easy and quick.
• Allowing for a quick visualization to determine if the code base has any functional issues.
• Living documentation of functionality with new code written.
• Allowing for safe refactors of code, whether based on attempts to improve code quality or a changed requirement.

That final point is worth dwelling on for a moment. The TDD approach requires that the evolving code base is cleaned up frequently so that new tests and code are easy to introduce. That usually means that code moves from its current place to where it more logically belongs in the software. That has the effect of reducing any extraneous duplication of code and enforces a strong discipline around objects, classes, modules, etc. In this way, the overall maintainability of the software increases incrementally.

The improvement in readability and maintainability will pay huge dividends during the expected life cycle of the software. Following a TDD methodology requires developers to focus on writing smaller units of testable code. By following the TDD methodology, this leads to more modularized, flexible and extensible software.