test-driven-development

To start test-driven development, write a failing unit test for the new feature, implement the minimal code required to make it pass, and then refactor the code while keeping the test green. Repeat this cycle until the feature is complete.

Test-driven development is a software engineering practice where you define real, runnable tests before writing production code. You need it to reduce regressions, validate expected failures, and guide design choices across new features, bug fixes, and refactors.

Yes, you can apply test-first discipline to bug fixes and refactoring. By validating behavior with tests before and after changes, you ensure safer refactoring and confirm that the minimal, well-factored code produced continues to pass all tests.

The best way to guide feature work is to establish a repeatable red-green-refactor cycle. Define a failing test, validate the failure, write minimal production code to pass the test, and iterate until all tests pass, ensuring well-factored code.

Test-driven development supports teams adopting it across architectural changes and maintenance by enforcing test-first discipline. It validates behavior before and after modifications, ensuring minimal code changes that pass tests and reduce regressions during structural updates.