This file is byte-identical to the first copy the registry indexed, one of 4 indexed copies. Same content hash, so the same checks give both the same grade.
test-driven-development from nota-america/forgecat-agent-profiles is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
Drives development with tests using the red-green-refactor loop. Use when implementing any logic, fixing any bug, or changing any behavior. Use when you need to prove that code works, when a bug report arrives, or when you're about to modify existing functionality.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Test-Driven Development
## Overview
Write a failing test before writing the code that makes it pass. For bug fixes, reproduce the bug with a test before attempting a fix. Tests are proof — "seems right" is not done. A codebase with good tests is an AI agent's superpower; a codebase without tests is a liability.
## When to Use
- Implementing any new logic or behavior
- Fixing any bug (the Prove-It Pattern)
- Modifying existing functionality
- Adding edge case handling
- Any change that could break existing behavior
**When NOT to use:** Pure configuration changes, documentation updates, or static content changes that have no behavioral impact.
**Related:** For browser-based changes, combine TDD with runtime verification using Chrome DevTools MCP — see the Browser Testing section below.
## Discover the Stack First
The TDD cycle is universal; the commands are not. Before writing the first test, discover how *this* repository tests, and use its commands for every RED, GREEN, and verification step:
- **Language and build system** — `package.json`, `pom.xml`/`build.gradle`, `pyproject.toml`, `go.mod`, `Cargo.toml`, `Gemfile`, a `Makefile`
…
The line at the top of this page pins the label git:20260916.3a6b22e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_xzoyo5rpltwggomm
GET https://markdownregistry.com/api/v1/resolve?ref=nota-america/forgecat-agent-profiles/test-driven-development
GET https://markdownregistry.com/api/v1/blob/7c0c6ac057c19d7f8be65d9f49c3a638703b868f4625c78b70da5439d5d74fca
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/api-and-interface-design/SKILL.md · Guides stable API and interface design. Use when designing APIs,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/browser-testing-with-devtools/SKILL.md · Tests in real browsers via Chrome DevTools MCP. Use when building
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/ci-cd-and-automation/SKILL.md · Automates CI/CD pipeline setup. Use when setting up or modifying
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/code-review-and-quality/SKILL.md · Conducts multi-axis code review. Use before merging any change. Use
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/code-simplification/SKILL.md · Simplifies code for clarity. Use when refactoring code for clarity
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/constraint-driven-development/SKILL.md · Establishes a project's quality bar as a written contract and stops
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/context-engineering/SKILL.md · Optimizes agent context setup. Use when starting a new session,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/deprecation-and-migration/SKILL.md · Manages deprecation and migration. Use when removing old systems,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/documentation-and-adrs/SKILL.md · Records decisions and documentation. Use when you need to document
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/doubt-driven-development/SKILL.md · Subjects every non-trivial decision to a fresh-context adversarial
addyosmani/agent-skills · skills/test-driven-development/SKILL.md · Drives development with tests using the red-green-refactor loop. Use when implementing any logic, fixing any bug, or…
mvschwarz/openrig · skills/_canonical/process/test-driven-development/SKILL.md · Use when implementing any feature or bugfix, before writing implementation code
mvschwarz/openrig · packages/daemon/specs/agents/shared/skills/process/test-driven-development/SKILL.md · Use when implementing any feature or bugfix, before writing implementation code
cbrock84/headcount · plugins/technology/skills/test-driven-development/SKILL.md · Drives implementation by writing a failing test first, then the smallest code that passes it. Use this before writing…
a5c-ai/babysitter · library/methodologies/superpowers/skills/test-driven-development/SKILL.md · Use when implementing any feature or bugfix, before writing implementation code. Enforces RED-GREEN-REFACTOR cycle.
a5c-ai/babysitter · library/methodologies/rpikit/skills/test-driven-development/SKILL.md · Test-first development practice where test specifications are written before production code, integrated into plan…
