Getting Smart With Test Driven Development

Test Driven Development

In the chase for speed, a product’s quality assurance is often deprioritized over meeting a project’s deadline. 

According to Coralogix, a data analytics company, a developer builds 70 bugs every 1000 lines of code on average. Debugging these bugs takes up to 75% of a developer’s time, which is roughly 1500 hours per year. As a result, the developers struggle to meet strict deadlines and face budget constraints and, therefore, fail to write and develop error-free codes. 

Testers detect bugs that developers leave while developing the software code. But sometimes, even testing teams also miss out on major bugs. 

In such situations, Test-driven Development (TDD) resolves the quality vs. speed dilemma once and for all. TDD puts tests before coding which assures to meet quality requirements throughout the development process.  

Kent Beck, top global thought leader in testing, in his book Test Driven Development: By Example, says, 

“If you’re happily slamming some code together that works and you’re happy never looking at the result again, TDD is not for you. TDD helps you to pay attention to the right issues at the right time so you can make your designs cleaner, you can refine your designs as you learn.” 

Kent Beck

The question is: how? Read on to crack the TDD code and learn how it is a game-changing technique for high-quality software releases

TDD for a faster development cycle

There is enough research available on the internet that supports TDD for a faster software development cycle.


In a case study, the software engineering teams of IBM and Microsoft experienced a 15% to 35% increase in the early development time after using the TDD technique.

From a different perspective, Microsoft and IBM studies suggest that the software experts observed a long-term increase in quality. Moreover, the software engineers were more determined to implement new features and make changes due to increased test coverage and time.


Live project documentation 

Testers using the TDD approach do not require writing lengthy and time-taking documentations. This is because the test cases written for feature requirements serve as brief documentation that comprises all the necessary user story details. This granularity and linkage with requirements help developers to write codes that should work according to the product specifications. This saves time and works for both testers and developers. 

Without TDD, a new team member remains unaware of recent changes and how he or she will interact with the recently written code — resulting in communication gaps and missed deadlines. 

Therefore, executing TDD from the start of a project allows new developers to understand the development process effortlessly. They can quickly go through the codebase and learn what code was written, reviewed, and tested in the periodic phases of software development via user story threads.

Fewer bugs with TDD

One of the primary benefits of TDD is that it generates fewer bugs. In the survey cited above, the engineers at Microsoft and IBM reasoned that after applying using TDD technique, the pre-release bug density dropped down between 40% and 90%. 

Optimum code quality and project design

TDD aligns well with the Don’t Repeat Yourself (DRY) philosophy. It states that programmers should focus on one feature until its test case is passed before moving to another code. This technique allows the development team to maintain a consistent codebase for easy bug detection and code reuse.

Furthermore, organized and clearly written code allows reusability every time a new change or addition is introduced to the system. Otherwise, complex code structures only make the software development processes more tedious and prolonged. 

Reduced project expenses 

TDD implementation drastically reduces the project development cost as a result of the above-discussed practices i.e.:

  • Easy to maintain and reusable code.
  • Seamless future patch releases with TDD solution.
  • You will have ready-to-use documentation for future purposes.
  • Budget-friendly solution for a sustainable company-client relationship.

These TDD tactics are highly time-efficient and, therefore, enable you to build a unique marketplace website or a SaaS product on a budget.

Code refactoring becomes easier than ever

Refactoring is another mandatory element of TDD. The major goal of code refactoring is the optimization of the existing code and making it simpler to use. A code that passes the initial tests for any improvement or specification can be refactored to agreeable standards, implying that the code meets both client and user expectations.

It is as simple as adding one more test → running it→ seeing if it fails → writing the code → refactoring the code → and repeating the process for code coverage.

How to perform TDD: A robust combination of testing and development

As discussed, the TDD approach is about writing tests that specify and verify what the code is supposed to do. Developers write code only after a test has failed. This, as a result, allows developers to write the code that passes the test criteria for the anticipated product.

The TDD cycle works as explained below: 

Test Driven Development cycle | Codica


Writing a test: Test cases are written for feature-specific requirements. The developer goes through the user stories to understand details and develop a code that should pass these tests. 

Test fails (red): Testers run the test cases after writing them. As there is no code that meets the feature requirements, the test fails. This validates that the testing framework is working as expected.

Write the code (green): The developer writes the code that passes the test after assuring that the feature is corresponding to the design. However, the code is not expected to pass the test flawlessly. 

Run tests: The tester can now rerun a test whenever a new code is released. This practice validates that any recent addition or update does not block the previous features.

Code refactoring: The code is then cleaned to improve the efficiency of the internal source code while maintaining the external functionalities intact. This stage removes code duplication. 

Repeat: These steps are repeated every time a new feature is developed to achieve maximum code coverage per feature to assure a user-friendly design and easy app maintenance in the future.

To all the the testers and developers: you have successfully uncovered how to crack the TDD code. Implement this approach in your testing, to ensure a glitch-free and smooth software development process!