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 kouroshez/coding-os --skill end-to-end-testinggit clone --depth 1 https://github.com/kouroshez/coding-osWrote 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/kouroshez/coding-os/end-to-end-testing)<a href="https://agentmods.dev/skills/kouroshez/coding-os/end-to-end-testing"><img src="https://agentmods.dev/badge/skills/kouroshez/coding-os/end-to-end-testing.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 | $0.00177 | $0.01323 |
| Opus 5 | $0.00088 | $0.00661 |
| Sonnet 5 | $0.00035 | $0.00265 |
| Haiku 4.5 | $0.00018 | $0.00132 |
Grade A, and why
end-to-end-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 6d 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 — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.
End-to-End Testing
End-to-end tests are the most valuable and the most expensive tests — they prove a real user journey works across the whole stack, and they break for unrelated reasons if written carelessly. The discipline: few but critical journeys, semantic locators, zero hard sleeps, and isolated data. A flaky end-to-end suite is worse than none — teams learn to ignore red.
Lint Playwright specs for flakiness anti-patterns:
python3 scripts/lint_e2e.py tests/**/*.spec.ts
Cover journeys, not units (it's the tip of the pyramid)
End-to-end tests are slow and broad — reserve them for the handful of journeys that, if broken, mean the product is down: sign up → log in, add to cart → checkout, the core create→read→update path. Everything else (edge cases, error states, validation) is cheaper and more reliable as unit/integration tests. Which test type for a given change is owned by testing-strategy — this skill is how to write the end-to-end ones well.
Playwright — locators + auto-wait (web)
// Wrong — brittle selector + a hard sleep = flaky and slow
await page.waitForTimeout(3000);
await page.click(".btn-primary.css-1x2y3z"); // generated class, breaks on rebuild
// Correct — semantic locator + auto-waiting assertion
await page.getByRole("button", { name: "Sign in" }).click(); // waits for actionable
await expect(page.getByText("Welcome")).toBeVisible(); // retries until true or times out
Playwright auto-waits for elements to be actionable — getByRole/getByLabel/
getByText plus web-first expect assertions retry automatically. A
waitForTimeout is always wrong: either too short (flaky) or too long (slow).
Prefer role/label/text locators (they double as accessibility checks — see
a11y) over CSS/XPath. Detail → references/playwright.md.
Maestro — flows for mobile
# flows/login.yaml
appId: com.example.app
---
- launchApp
- tapOn: "Email"
- inputText: "[email protected]"
- tapOn: "Sign in"
- assertVisible: "Welcome"
What ships with it
5 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.
- 6d ago First seen · 102 lines · 177 tokens per session scan A c5fb822c80ab
end-to-end-testing is a skill published in the GitHub repository kouroshez/coding-os (6 stars, last pushed 6d ago), licensed Apache-2.0. It adds 177 tokens to every session and 1,323 once invoked, about $0.0009 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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