What problem does it solve?
Standard test-driven development workflows miss critical guardrails that lead to silent spec errors in metric design, avoidable cumulative linter threshold violations from small code changes, and broken intermediate code states caused by autofix formatter hooks, resulting in rework and undetected defects.
Core Features & Use Cases
- Design-level metric falsification: Validates proposed scoring or heuristic metrics on real live data before implementation to catch spec errors that unit tests will never flag, preventing perfectly implemented but fundamentally flawed metrics.
- Shared definition extraction for comparable values: Eliminates silent drift between duplicate formula implementations by extracting shared, separately tested helper functions for values that must match across different parts of the codebase.
- GREEN-phase lint discipline: Runs project linters during the GREEN step of the TDD loop to catch cumulative complexity threshold violations early, when fixes are cheap, rather than at commit time when they require costly refactoring.
- Autofix-safe edit sequencing: Stages code edits to prevent formatter autofixers from stripping unused imports or breaking intermediate code states, avoiding NameErrors that only surface during test collection.
Use this skill when implementing a new scoring metric, adding a control-flow branch to a dense function, or working in a repository with active PostToolUse formatter hooks to eliminate common TDD pitfalls that standard workflows do not cover.
Quick Start
Use the test-driven-development-extras skill alongside your standard test-driven development workflow when implementing a new feature that computes a value matching an existing reported metric, adds a control-flow branch to an already dense function, or edits files in a repository with active autofix formatter hooks.
