staff-test-driven-development

Test-driven development for bug fixes is enforced by requiring a failing test before implementation, writing minimal code to satisfy the test, and verifying the failure occurs for the expected reason before refactoring.

The red-green-refactor cycle is a test-first process where you write a failing test, implement the smallest code change to pass it, and then refactor while ensuring tests remain green throughout the verification process.

To write a failing test first for a new feature, you draft a test defining the expected behavior, run it to confirm it fails specifically due to missing implementation, and then proceed to write the minimal production code required to make it pass.

Test-first development applies to behavior changes in existing software projects by enforcing strict verification guardrails, ensuring every logic modification or new API endpoint is backed by a proof of behavior before the code is refactored.

You can use this test-first approach for both new features and regression fixes, as it enforces disciplined red-green-refactor execution to verify that production code changes pass tests and prevent unverified code from slipping in.

Strict test-first development requires writing a failing test before any implementation, which may limit rapid prototyping speed by enforcing verification guardrails and minimal code increments for every behavior change or refactor.