7 Best Practices for Agile Test-Driven Development (TDD) Projects

Kent Beck, in his book ‘Test Driven Development: By Example,’ says, “If you’re happily slamming some code together that more or fewer works and you’re happy never looking at the result again, TDD is not for you. TDD rests on a charmingly naïve geeked assumption that you’ll be more successful if you write better code. TDD helps you pay attention to the right issues at the right time to make your designs cleaner and refine your designs as you learn.” 

Test–Driven Development (TDD) 

Test-driven development (TDD) is a minimalist software development process in which the tests are written before the actual code. By doing so, the method ensures maximum alignment between the requirements and the production code. The requirements are converted into particular test cases defining the needed features in a TDD software development process. Then, code is written based on the feature-driven test cases. When the tests are written before the code, the developers can focus better on the requirements and specifications. 

First, the code is written to fail the test. Once the test fails for the expected reasons, the developer writes minimal code to pass the test case. All the test cases should pass individually and in compilation and should not break or affect any existing feature or functionality. Then, the code is refactored to meet the standards, and duplicates are removed from the code base. TDD software development process results in flexible and bug-free code, high test coverage, and greater productivity of the tests. Designed as an offshoot of extreme programming, TDD follows the agile method of building software in iterations and involves clean, simple designs and code. 

Best TDD Practices Followed in Test–Driven Development Projects 

Let us talk about some of the best TDD practices to be followed in TDD projects: 

1. Avoid functional complexity

Focus on one functionality or feature at a time – keep it simple! Deliberate on it with the whole team to ensure the test case covers the desired functionality in every way possible. As the test case is the driver, it should be reviewed for correctness and completeness. 

2. Focus on what you need to achieve

Ensure you understand where the code needs to be called and frame the test suite accordingly.  Test cases should follow standard naming conventions and depict what needs to be achieved by the end of the development process. This is crucial as functionality keeps getting added with iterations. Future developers should be able to look at the test and easily deduce the intended functionality. 

3. Maintain code austerity

Ensure your code has just enough meat to satisfy your test case. This is a basic tenet of TDD. This minimizes the chances of defects and simplifies review and testing processes. However, do ensure the code is understandable and allows future enhancements. 

4. Test repeatedly

Test before coding and after coding. Then, test once again after code refactoring. This reinforces that no code is broken in any of the steps. During refactoring, ensure the new code is maintainable and adheres to the standards. The rule of thumb is to repeat testing whenever a code change, code move, or code merger occurs. 

5. Maintain code sanctity

Use version control tools to check out and check in code. This is important, specifically when more than one developer works on the code. Using continuous integration tools like Jenkins can avoid code merger issues. 

6. Application knowledge

In TDD, coding must be limited but effective in achieving its purpose without breaking anything else. Also, the new code should ideally pass the test case in the first run. Maintaining adequate system documentation, including a repository of test cases and engaging team members with good application knowledge, can ensure a smooth and successful project execution. 

7. Know when to use TDD

Lastly, TDD works best in specific scenarios like any other development concept. Use TDD for developments that can be quickly tested. Any prolonged or complex testing defeats the purpose of TDD. 

To sum up  

With TDD, development is more controlled, and as a result, defects are considerably reduced. Repetitive testing ensures each component in the system is working correctly at every step. Test-driven development is a perfect choice for functional testing but may not be sufficient for complex situations such as UI testing. If understood correctly, TDD is the simplest way to achieve high test coverage and better code quality. 

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