Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add mamahoos/dot-files --skill test-driven-developmentgit clone --depth 1 https://github.com/mamahoos/dot-filesWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/mamahoos/dot-files/test-driven-development)<a href="https://agentmods.dev/skills/mamahoos/dot-files/test-driven-development"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/test-driven-development/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mamahoos/dot-files/test-driven-development"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/test-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00092 | $0.03771 |
| Opus 5.5 | $0.00037 | $0.01508 |
| Sonnet 5.5 | $0.00018 | $0.00754 |
| Haiku 4.5 | $0.00009 | $0.00377 |
Grade A, and why
test-driven-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
98% identical to test-driven-development — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 400 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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, aMakefile - Checked-in wrappers — prefer
./gradlew,./mvnw,make test, or a repo script over globally installed tools - Test framework and configuration — and how it runs a single focused test vs the full suite
- Existing conventions — where tests live, how files are named, what patterns neighboring tests follow
- Documented commands — README, CONTRIBUTING, and CI workflows show the commands that actually gate merges
Run the repository's focused-test command during the loop and its full-suite command before completion. Never assume a default like npm test — a Gradle, Cargo, or pytest project has its own equivalent.
The examples below use TypeScript for illustration; the workflow is identical in any language once you've discovered the project's own tooling.
The TDD Cycle
RED GREEN REFACTOR
Write a test Write minimal code Clean up the
that fails ──→ to make it pass ──→ implementation ──→ (repeat)
│ │ │
▼ ▼ ▼
Test FAILS Test PASSES Tests still PASS
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago Changed · +35 tokens per session 43d06bdd7cbe
- 1mo ago Changed · +7 tokens per session a82049a031e6
- 1mo ago First seen · 400 lines · 50 tokens per session scan A a65ec1f2cc60
test-driven-development is a skill published in the GitHub repository mamahoos/dot-files (5 stars, last pushed yesterday), licensed MIT. It adds 92 tokens to every session and 3,771 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to test-driven-development, differing in 1 line, and is treated as a copy.
Other skills, from other repositories
test-driven-development
Use when implementing any feature or bugfix, before writing implementation code.
django-tdd
Use when testing Django applications with pytest - TDD workflow, pytest-django setup, factoryboy and model-bakery fixtures, DRF API testing, mocking and patching, integration tests, or coverage.
laravel-tdd
Test-driven development for Laravel with PHPUnit and Pest, factories, database testing, fakes, and coverage targets.
tdd
Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious cheap local test target. Skip when the test path is unclear, expensive, integration-heavy, or not requested.
gh-issue
Fetch GitHub issue, create branch, plan and implement with TDD, then open PR.
add-assertion
Add new assertion function with comprehensive tests following TDD.