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 solofounder-ai/solofounder --skill tdd-methodologygit clone --depth 1 https://github.com/solofounder-ai/solofounderWrote 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/solofounder-ai/solofounder/tdd-methodology)<a href="https://agentmods.dev/skills/solofounder-ai/solofounder/tdd-methodology"><img src="https://agentmods.dev/badge/skills/solofounder-ai/solofounder/tdd-methodology/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/solofounder-ai/solofounder/tdd-methodology"><img src="https://agentmods.dev/badge/skills/solofounder-ai/solofounder/tdd-methodology.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 | $0.00018 | $0.02407 |
| Opus 5 | $0.00009 | $0.01203 |
| Sonnet 5 | $0.00004 | $0.00481 |
| Haiku 4.5 | $0.00002 | $0.00241 |
Grade A, and why
tdd-methodology 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 12d 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
91% identical to compose:tdd — 34 lines 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 — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-Driven Development (TDD)
Overview
Write the test first. Watch it fail. Write minimal code to pass.
Core principle: If you didn't watch the test fail, you don't know if it tests the right thing.
Violating the letter of the rules is violating the spirit of the rules.
When to Use
Always:
- New features
- Bug fixes
- Refactoring
- Behavior changes
Exceptions (ask your human partner):
- Throwaway prototypes
- Generated code
- Configuration files
Thinking "skip TDD just this once"? Stop. That's rationalization.
The Iron Law
NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST
Write code before the test? Delete it. Start over.
No exceptions:
- Don't keep it as "reference"
- Don't "adapt" it while writing tests
- Don't look at it
- Delete means delete
Implement fresh from tests. Period.
Red-Green-Refactor
digraph tdd_cycle {
rankdir=LR;
red [label="RED\nWrite failing test", shape=box, style=filled, fillcolor="#ffcccc"];
verify_red [label="Verify fails\ncorrectly", shape=diamond];
green [label="GREEN\nMinimal code", shape=box, style=filled, fillcolor="#ccffcc"];
verify_green [label="Verify passes\nAll green", shape=diamond];
refactor [label="REFACTOR\nClean up", shape=box, style=filled, fillcolor="#ccccff"];
next [label="Next", shape=ellipse];
red -> verify_red;
verify_red -> green [label="yes"];
verify_red -> red [label="wrong\nfailure"];
green -> verify_green;
verify_green -> refactor [label="yes"];
verify_green -> green [label="no"];
refactor -> verify_green [label="stay\ngreen"];
verify_green -> next;
next -> red;
}
RED - Write Failing Test
Write one minimal test showing what should happen.
const result = await retryOperation(operation);
expect(result).toBe('success'); expect(attempts).toBe(3); });
Clear name, tests real behavior, one thing
</Good>
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.
- 12d ago First seen · 372 lines · 18 tokens per session scan A 240e8c2b3d95
tdd-methodology is a skill published in the GitHub repository solofounder-ai/solofounder (3 stars, last pushed 5mo ago), licensed MIT. It adds 18 tokens to every session and 2,407 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to compose:tdd, differing in 34 lines, and is treated as a copy.
Other skills, from other repositories
writing-plans
Use when you have a spec or requirements for a multi-step task, before touching code.
test-driven-development
Use when implementing any feature or bugfix, before writing implementation code.
x-qdev
A compact development workflow for a small, clearly defined code change. It keeps the requirement, initially failing tests, implementation, and real verification results in one task document, following TDD, or test-driven development.
orchestrate
A workflow manager for a full test-driven development cycle, where tests are written before implementation and code is then improved and reviewed. It coordinates planning, failing tests, implementation, refactoring, review, and committing changes.
codify-insight
A review skill that sorts lessons from completed TDD cycles into rules to keep, items to postpone, or items not to keep. TDD, or test-driven development, is a practice of writing tests around a change as part of its development cycle.
commit
A Git workflow skill that completes a TDD cycle by committing changes after required review, tests, logs, and retrospective checks pass. Git is a version-control system that records code changes and commits.