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 agentmods add skills/mtvrkan/senior-dev-kit/test-writernpx skills add mtvrkan/senior-dev-kit --skill test-writergit clone --depth 1 https://github.com/mtvrkan/senior-dev-kitWrote 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/mtvrkan/senior-dev-kit/test-writer)<a href="https://agentmods.dev/skills/mtvrkan/senior-dev-kit/test-writer"><img src="https://agentmods.dev/badge/skills/mtvrkan/senior-dev-kit/test-writer.svg" alt="Measured on agentmods" 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 | $0.00035 | $0.00391 |
| Opus 5 | $0.00017 | $0.00196 |
| Sonnet 5 | $0.00007 | $0.00078 |
| Haiku 4.5 | $0.00003 | $0.00039 |
Grade A, and why
test-writer 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 5d 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.
What it actually says
test-writer
Fires for backend service/controller/repo/handler/use-case, mobile ViewModel/UseCase/Repository, frontend server action/API route. Not for pure UI changes.
Process
- Read budget: changed file + existing test file (
*.spec.ts/*_test.go/test_*.py) — 2 files max. - Write 3-6 cases, one assertion each: happy path (1) + edge/boundary (1-2) + error (1) + regression if bugfix (1).
- Mock: external HTTP APIs, email/payment gateways, external SDKs, Date.now(), Math.random(). Never mock internal pure functions, utility functions, type mappers, constants, or your own DB (use a test DB — see
rules/300-testing.md). - Run targeted only:
jest [file].spec.ts --no-coverage|vitest run [file]|go test ./pkg/... -run TestFn|pytest [file] -x -q|./gradlew test --tests "*.Class"
Output
TEST: [test names] | FILE: [path] | RUN: [command — ✓ N passed] | MOCKS: [list | none]
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.
- 5d ago First seen · 28 lines · 35 tokens per session scan A 07ec93be2d50
test-writer is a skill published in the GitHub repository mtvrkan/senior-dev-kit (5 stars, last pushed 5d ago), licensed MIT. It adds 35 tokens to every session and 391 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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