Which two concepts describe test-driven development?

Test-Driven Development (TDD) is a software development approach where tests are written before the actual code. The process follows these steps:

Write a test before writing code (B): Developers write tests for a new function or feature before implementing it. This ensures that the tests define what the code is supposed to do.

Enable code refactoring (A): Because tests are written first, TDD supports continuous refactoring of the code. Developers can confidently improve and clean up code, knowing that existing functionality is verified by the tests.