test-driven-development

Test-driven development (TDD) is a practice where you write failing tests defining expected behavior before implementing code. It improves software quality by treating tests as contracts, ensuring robust and maintainable outcomes through an iterative development cycle.

Start the TDD workflow by writing a failing test defining expected behavior for your new feature. Next, write implementation code to make the test pass, then refactor while ensuring the test contract remains intact throughout the iterative cycle.

Use mocking strategies in test-driven development when isolating components across architectural boundaries. Mocking balances unit and integration tests by simulating external dependencies, allowing you to focus on verifying the specific contract of the module under test.

You should fix the implementation instead of modifying a failing test because TDD treats tests as contracts. Changing a test to pass violates defined expected behavior, whereas fixing the implementation ensures your software actually meets the agreed-upon requirements.

Yes, test-driven development works effectively within agile environments. TDD's iterative workflow of writing tests first and implementing code to pass them aligns directly with agile principles, supporting continuous integration and delivering robust, well-tested software features incrementally.