test-driven-development

The red-green-refactor cycle in test-driven development is a strict test-first workflow where you write a failing test, implement minimal code to pass it, and then refactor. This enforces validating requirements by failing tests first, preventing unverified behavior and brittle changes.

To write unit tests before production code in JavaScript, start by writing a failing test for the desired behavior, then implement minimal code to pass the test and refactor. This test-first discipline ensures deterministic tests and clean code across your JavaScript or TypeScript projects.

You should use test-driven development for refactoring when you need to prevent regressions and maintain test coverage. It provides strict test-first guidance during feature development, bug fixes, and refactoring to ensure changes remain deterministic and code stays maintainable.

Yes, you can apply test-driven development to TypeScript projects. The workflow applies across JavaScript and TypeScript projects, focusing on deterministic tests and clean code while guiding feature development, bug fixes, and refactoring through a strict red-green-refactor cycle.

The best way to prevent regressions when writing new features is to enforce test-driven development. By validating requirements through a failing test first and maintaining a strict red-green-refactor cycle, you ensure test coverage and prevent unverified behavior in production code.

Writing production code without tests risks brittle changes because behavior remains unverified. Test-driven development solves this by prescribing a test-first workflow that validates requirements through failing tests, ensuring test coverage and maintainable code through disciplined red-green-refactor cycles.