What is test-driven development?

Test-driven Development (TDD) is a software development practice that focuses on creating test cases before developing code. These test cases are meant to determine how the software will work. It starts by developing unit tests for every small functionality to test the software at every development stage continuously. If the code fails the test, the TDD framework instructs developers to write new code. The new code is developed to pass the test, so it must be different. Test-driven Development enables the development of simple, bug-free, and unrepeated code.

Test-driven Development Phases

Creating Precise Tests

Developers need to create precise unit tests to verify the functionality of specific software features. They must ensure that the test compiles so that it can execute. Also, you should write the test case before the code. This is a challenge, but it ensures that the developer understands the functionality required to create the test case. The test case is not developed to show code works but rather to test the expected feature. Try to run the test without any code. It should fail to show that it is working correctly, and it will not always pass.

Correcting Code

After testing the code, developers need to make the minimal changes required to correct the code to run when re-executed. Refactor the code for readability and maintainability. Also, run the test after every refactoring to ensure nothing is broken.


You should repeat the cycle for each new piece of functionality. Tests should be small and incremental to avoid missing any minor mistakes in the code. Also, if the new code fails some tests, the programmer can revert rather than debug excessively.

Advantages of Test-driven Developments

Modular Software Design Concept

When using TDD, developers narrow their focus to a single feature at a time without moving to the next one. Code quality is enhanced when written in such an iteration, making it easier to discover bugs and reuse the code. When the code eventually becomes modular and unit-testable, it contributes to better software architecture.

Better Code Documentations

Test-driven Development means there’s no immediate need to spend time creating detailed documentation that is extremely hard to maintain. The simple unit tests can act as documentation to illustrate how the code is supposed to work. It also frees up the time and resources of both programmers and testers to focus on other tasks.

Less Debugging

Bug-free code is the primary benefit of Test-driven Development. When the code has fewer bugs and errors, it’s easier to spend less time fixing them than on other programming methodologies. The more extensive codebases get, the harder they are to track bugs and change. This leaves the software at risk of damage. However, the TDD approach produces higher test coverage by testing the code before completion.

Smooth Refactoring

Test-driven Development makes code more manageable. Refactoring is a mandatory part of the TDD process, optimizing existing code to make it easier to introduce. If the code fails the initial tests, it can be rewritten to match the acceptable standards.

Software developers use the test-driven development approach to find all the bugs before they can damage the whole system. This practice ensures consistent code quality as it is broken into tiny units that are coded and tested independently.

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