Test-Driven Development Explained
Write the test first, then the code. The discipline that produces reliable software by design.
Test-Driven Development (TDD)
A development practice where tests are written before the code they test. The cycle is: write a failing test, write the minimum code to pass it, then refactor.
Explanation
TDD follows a strict red-green-refactor cycle. First, write a test that describes the desired behavior (it will fail because the code does not exist yet — "red"). Then, write the simplest code that makes the test pass ("green"). Finally, refactor the code while keeping tests green. TDD ensures every line of production code is covered by a test and that the code is designed to be testable. It works best for business logic, algorithms, and pure functions.
Bookuvai Implementation
Bookuvai teams practice TDD for all business logic and API endpoints. Our AI PM includes test requirements in each user story, and code reviews verify that tests were written before implementation. Integration and e2e tests supplement TDD unit tests.
Related Terms
Frequently Asked Questions
- Does TDD slow down development?
- Initially, yes — writing tests first takes more time upfront. But TDD reduces debugging time, prevents regressions, and makes refactoring safe. Net productivity is typically higher over the project lifecycle.
- Should everything be developed with TDD?
- TDD works best for business logic, algorithms, and data transformations. UI components, CSS layout, and prototype/exploratory code are often better suited to testing after implementation.