test-driven-development

Test-driven development for bug fixes and refactoring requires writing a failing test that captures the desired behavior before changing production code. You then implement the minimal change to make it pass and clean up safely.

The red-green-refactor workflow in unit testing is a strict test-first loop where you write a failing test, implement minimal code to pass it, then clean up safely. It enforces behavior validation throughout feature development.

To avoid overfitting unit tests to mocks, focus tests on verifying real outcomes and behavior changes rather than implementation details. This prevents fragile implementations and preserves confidence while changing code.

You need to write failing tests before production code when adding new features, fixing regressions, or modifying behavior in software projects. This prevents fragile implementations by defining expected behavior upfront.

Validating test failures during test-first development involves checking that the failing test accurately captures the requirement before writing code. You then implement only enough production code to make the test pass.

Test-driven development works without external mocking dependencies by encouraging behavior-focused testing that verifies real outcomes. It provides practical guardrails to validate failures and passes without overfitting to mocks.