TDD- The Leading Approach of Software Development

Identifying a problem and finding its root cause plays a significant role in software development. There are several points of view about the best way to approach software development; a methodology that can ensure cleaner code and make it easier to locate critical spots will make a huge difference. The TDD or Test-Driven Development approach is unique as it seeks to fail the code before developing it further.  

The TDD Approach

TDD is a developmental approach that integrates with the concept of test-first programming. TDD focuses mainly on the specification and programming technique to write clean code that works. It works primarily through refactoring, which means writing a unit test before writing the production code to pass that test. It implements two philosophies in the software development phase:

  • Writing a unit test that fails 
  • Writing production code to pass the failed test 

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Fail-Pass-Refactor Theory

TDD-Reverse Thinking Approach

Fail: Make the written test fail. 

Pass: Make the test pass by implementing proper coding.

Refactor: Remove duplication and improve the design and readability of code.   You must be interested in: How To Enhance Your Software Testing Cycle By 80%?

Let’s “Bug It to Debug!!”

With acceptance tests and developer tests as inputs, TDD simplifies the code and allows for less documentation. As the primary objective of a programmer is on the task at hand, it ensures the written code is covered by at least one test. 

Likewise, development continues until the failed test is passed, confirming that the required functionality has been correctly implemented. This approach ensures earlier defect finding and fixing, limiting the code’s number of defects. Also, as it eliminates the defect early, tedious debugging is avoided. 

TDD vs. Agile 

Agile development focuses on delivering a quality product by accommodating continuous feedback from clients. Due to the changing requirements of sprint cycles, the quality of the software gets hampered. 

The test-first approach in TDD eliminates the above bottleneck by receiving requirements with clarity, writing unit tests before writing production code to prevent later fixes, and finally, refactoring it. This way, Agile and TDD go hand-in-hand to deliver a digitally assured product

How TDD Works

Customer requirements are turned into tests, and software is written to pass the new test. As the new tests are written with the customer requirements in mind, only the objectives defined by the scope are covered in the unit test. It is necessary to change the production code only if any test fails; otherwise, refactoring is adequate to optimize the code. 

Simple Modular Design-Clean Code  

Developers can achieve better architecture by picking up one feature at a time and not moving to the next feature until the test has been passed. Iteratively doing this helps improve the code quality, identify defects quickly and ensure the code can be reused.  

Refactoring and Maintenance Made Easier 

As tests cover each functionality, any change in the code could introduce an easily detectable error. Developers can fix bugs quickly, and code optimization achieves greater code readability. Doing this also helps decrease the percentage of defects gradually.  

Effective Teamwork 

TDD is a team-oriented approach that involves the concept of pair programming. Collaboration and knowledge sharing have become more accessible and more efficient in TDD. Any team member can work confidently on other team members’ code; the test will inform them if the code changes unexpectedly.  

High Coverage Density 

In the traditional approach, testing is narrowed down to critical functionalities due to the limited period. Whereas in TDD, the maximum coverage is attained for the software by developing one test for each functionality. TDD helps achieve high test coverage and density compared to other developmental approaches. 


How the test is designed acts as documentation for all new team members. The test code explains what the code does and how it integrates with another interface. Thus, TDD prevents developers from writing documentation that is unsustainable to maintain. 

We know TDD is an excellent methodology, and we know that not all application parts are easy to test using simple unit tests. In that case, TDD would be a replacement for the traditional methodology.  

TDD assures the developer that the bug will not appear in the system again as it was already fixed (Red ->Green). It also minimizes the system testing effort. However, one cannot wholly rely on TDD as a “sorcerer that drives away bugs from code.” Acceptance testing is indispensable before delivering the final product to the client. 

The primary driving factor behind digital assurance should be to keep up the brand promise made to the customer as opposed to the drive to exclusively achieve speed, scale, security and innovation on the cloud.