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 tslateman/duet --skill testinggit clone --depth 1 https://github.com/tslateman/duetWrote 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/tslateman/duet/testing)<a href="https://agentmods.dev/skills/tslateman/duet/testing"><img src="https://agentmods.dev/badge/skills/tslateman/duet/testing/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/tslateman/duet/testing"><img src="https://agentmods.dev/badge/skills/tslateman/duet/testing.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 | $0.00066 | $0.01838 |
| Opus 5.5 | $0.00026 | $0.00735 |
| Sonnet 5.5 | $0.00013 | $0.00368 |
| Haiku 4.5 | $0.00007 | $0.00184 |
Grade A, and why
testing 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 215 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Design as Thinking
Overview
Test strategy, not test generation. Treat test design as an act of specification, articulate the contract, find the boundaries, surface hidden assumptions. Use Beck's Test Desiderata to make testing tradeoffs deliberate instead of accidental.
Beck's 12 Test Desiderata
Every test balances these properties. No test maximizes all twelve. The skill is knowing which to prioritize.
| Property | Definition | Tension |
|---|---|---|
| Isolated | Same results regardless of run order | vs. speed (shared setup) |
| Composable | Test dimensions of variability separately | vs. writability (more tests) |
| Deterministic | Same results if nothing changes | vs. realism (real services) |
| Fast | Run quickly | vs. predictiveness (integration) |
| Writable | Cheap to write relative to code cost | vs. thoroughness |
| Readable | Comprehensible, invokes motivation | vs. conciseness |
| Behavioral | Sensitive to behavior changes | vs. structure-insensitivity |
| Structure-insensitive | Unaffected by refactoring | vs. behavioral sensitivity |
| Automated | No human intervention needed | vs. exploratory testing |
| Specific | Failure cause is obvious | vs. breadth of coverage |
| Predictive | Passing means production-ready | vs. speed and isolation |
| Inspiring | Passing builds confidence to deploy | vs. all other properties |
See references/desiderata.md for application guidance.
Test Design Workflow
1. Articulate the Contract
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 1mo ago First seen · 215 lines · 66 tokens per session scan A 2fbc0c857080
testing is a skill published in the GitHub repository tslateman/duet (1 stars, last pushed 1mo ago), licensed MIT. It adds 66 tokens to every session and 1,838 once invoked, about $0.0003 per session on Opus 5.5. 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.
Other skills, from other repositories
launch-plan
Generate a comprehensive launch checklist from a PRD, covering release criteria, QA, comms, rollback, metrics, and stakeholder prep. Slash command: /launch.
run
The single lifecycle entry point — take one or more tickets and drive each through its whole lifecycle (investigate, red tests, implement, gates, review, PR, merge, archive), interleaving them. Lean by default — one worker per ticket runs red tests, implementation and the gate scripts in one worktree, then…
slop-check
Inspect a branch diff for AI slop — tests rewritten to pass, assertions inverted, vacuous or tautological tests, swallowed errors — and return each finding with its location, the signal that identified it, a severity, and one overall verdict. Reports only; never fixes.
grill
Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use /slopstop:grill to stress-test a plan — typically before breaking it into tickets.
vacuity-check
Mechanically prove whether each named test would already have passed against the pre-branch code by re-running it, by node-id, in a scratch worktree checked out at the base commit. Returns a per-node-id verdict (vacuous / meaningful / could-not-determine) with the exit status as evidence, plus one overall verdict.
release-notes
Generate and publish concise, evidence-based notes in the body of the latest existing GitHub Release. Use only when the user explicitly invokes $release-notes or explicitly asks to update the latest existing GitHub Release body. Do not invoke for general release planning, changelog, tag, or version tasks.