Test-Driven Development (TDD) is a software engineering practice in which automated tests are written before the actual code. This approach ensures that the code meets specified requirements and helps detect errors early in the development cycle.
TDD follows a repetitive cycle: write a failing test, implement the minimal code to pass it, then refactor while ensuring all tests still pass. This cycle promotes cleaner code, higher test coverage, and better maintainability. It is commonly used in agile environments and continuous integration pipelines.
- Write failing unit tests before implementing functionality
- Refactor code continuously while maintaining test pass rates
- Use testing frameworks such as JUnit, pytest, or Jest
- Collaborate with developers and QA to define test criteria
- Integrate tests into build and deployment processes
Roles in software development—especially backend, frontend, and full-stack engineers—frequently apply TDD to build robust applications. It is widely adopted in industries requiring high reliability, such as fintech, healthcare, and SaaS. Knowledge of TDD includes understanding assertion libraries, mocking, test runners, and refactoring techniques. Employers expect practitioners to write clear, maintainable tests and use TDD to guide system design and reduce technical debt.
