addy-test-driven-development

Test-driven development is a practice where you write a failing test that captures desired behavior before implementing the minimal code to pass it. This reduces regressions and facilitates bug fixes by verifying behavior upfront.

The Prove-It pattern in unit testing reproduces a bug by writing a failing test that captures the erroneous behavior. You then implement the minimal code fix to make the test pass, ensuring the regression is permanently documented in your test suite.

Start writing tests before code by identifying the desired behavior and writing a failing test that captures it. Then, implement the minimal code required to make the test pass, and finally refactor the implementation for clarity without breaking the test.

Test-driven development maintains code health during refactoring by ensuring a robust test suite covers edge cases. This incremental quality assurance gives you confidence that refactoring existing features will not introduce unexpected regressions.

You should reconsider test-driven development when exploring highly experimental code where desired behavior is not yet defined. TDD requires a clear understanding of expected outcomes upfront to write a meaningful failing test before implementation.