test-driven-development

Test-driven development is a test-first discipline where you write a failing test, implement minimal code to pass it, then refactor while keeping tests green. The red-green-refactor cycle reduces bugs and facilitates safer refactoring by ensuring behavior is verified before changes are committed.

To start writing unit tests before production code, write a failing test that specifies the expected behavior for your feature. Implement the minimal code required to make the test pass, then refactor the code for clarity while ensuring the tests remain green.

Yes, test-driven development applies to bug fixes and refactors across software projects where automated verification matters. You write a failing test that reproduces the bug or verifies the intended behavior, then implement minimal changes to pass the test.

The best way to prevent regressions is enforcing a pre-commit safety check that prevents production code without a failing test. Test-driven development guards against regressions by requiring automated verification of expected behavior before changes are committed.

Test-driven development requires writing tests before implementation because a failing test guides the minimal code needed, reducing bugs and preventing over-engineering. This discipline ensures tests describe intended behavior and serve as living documentation for future changes.