Borrowing it
Nothing to install: this file belongs to timothywarner/copilot-dev. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/timothywarner/copilot-dev/main/.github/skills/webapp-testing/SKILL.mdgit clone --depth 1 https://github.com/timothywarner/copilot-devWrote 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/timothywarner/copilot-dev/webapp-testing)<a href="https://agentmods.dev/skills/timothywarner/copilot-dev/webapp-testing"><img src="https://agentmods.dev/badge/skills/timothywarner/copilot-dev/webapp-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/timothywarner/copilot-dev/webapp-testing"><img src="https://agentmods.dev/badge/skills/timothywarner/copilot-dev/webapp-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00071 | $0.01857 |
| Opus 5.5 | $0.00028 | $0.00743 |
| Sonnet 5.5 | $0.00014 | $0.00371 |
| Haiku 4.5 | $0.00007 | $0.00186 |
Grade A, and why
webapp-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 2mo 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 — 210 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Webapp Testing Skill
You are an expert in writing E2E and component tests for web applications using Playwright (for browser-based tests) and Jest + Testing Library (for component/unit tests). When this skill is active, follow every step below precisely.
Step 1: Identify the Target File and Testable Flows
Before writing a single line of test code:
- Read the target HTML, component, or route file completely.
- Enumerate every user flow visible in the UI:
- Form submissions (login, register, search, checkout)
- Navigation (links, breadcrumbs, tabs, modals)
- State changes (error messages, success banners, loading spinners)
- Authentication gates (redirect to login, session expiry)
- Prioritize flows by risk: authentication > data mutation > read-only display.
- Ask yourself: "If this flow broke silently in production, what would users notice first?" — test that first.
Step 2: Choose the Right Test Type
| Scenario | Test Type | Tool |
|---|---|---|
| Full browser flow (login → dashboard) | E2E | Playwright |
| Single component rendering | Component | Jest + Testing Library |
| API response handling in UI | Integration | Playwright with mock routes |
| Accessibility | A11y | Playwright + axe-core |
Step 3: Selector Strategy (Accessibility-First)
Always prefer selectors in this order:
// 1. BEST: Role + accessible name (resilient to CSS/layout changes)
await page.getByRole('button', { name: 'Sign in' }).click();
await page.getByRole('textbox', { name: 'Email address' }).fill('[email protected]');
// 2. GOOD: Label text (tied to semantic HTML)
await page.getByLabel('Password').fill('secret');
// 3. OK: Placeholder text (only if no label exists)
await page.getByPlaceholder('Enter your email').fill('[email protected]');
// 4. LAST RESORT: data-testid (when no semantic option exists)
await page.getByTestId('submit-btn').click();
// NEVER USE: CSS class names, XPath, positional selectors
// BAD:
await page.locator('.btn-primary').click(); // breaks on CSS refactor
await page.locator('//button[1]').click(); // brittle, breaks on DOM changes
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.
- 2mo ago First seen · 210 lines · 71 tokens per session scan A 77feb1328df7
webapp-testing is a skill published in the GitHub repository timothywarner/copilot-dev (46 stars, last pushed 1mo ago), licensed MIT. It adds 71 tokens to every session and 1,857 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 2026-08-30.
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