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 JakubMikolajek/codex-skills-collection --skill e2e-testinggit clone --depth 1 https://github.com/JakubMikolajek/codex-skills-collectionWrote 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/jakubmikolajek/codex-skills-collection/e2e-testing)<a href="https://agentmods.dev/skills/jakubmikolajek/codex-skills-collection/e2e-testing"><img src="https://agentmods.dev/badge/skills/jakubmikolajek/codex-skills-collection/e2e-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/jakubmikolajek/codex-skills-collection/e2e-testing"><img src="https://agentmods.dev/badge/skills/jakubmikolajek/codex-skills-collection/e2e-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 | $0.00046 | $0.00509 |
| Opus 5.5 | $0.00018 | $0.00204 |
| Sonnet 5.5 | $0.00009 | $0.00102 |
| Haiku 4.5 | $0.00005 | $0.00051 |
Grade A, and why
e2e-testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
E2E Testing Patterns & Practices
Page Object Pattern
export class FeaturePage {
constructor(readonly page: Page) {}
get submitBtn() {
return this.page.getByRole('button', { name: 'Submit' });
}
async navigate() { await this.page.goto('/feature'); }
}
Test Structure
test('should [behavior] when [condition]', async ({ page }) => {
const id = `test-${Date.now()}-${test.info().parallelIndex}`;
// Arrange → Act → Assert
});
Mocking (external APIs only)
await page.route('**/api/external/**', route => route.fulfill({ status: 200, body: '{}' }));
Verification Loop
RUN → FAIL? → DEBUG (browser_snapshot) → FIX → REPEAT
| Rule | Limit |
|---|---|
| Max per test | 5 iterations → test.fixme() |
| Max per suite | 15 iterations → stop |
| Flaky detection | 3 pass/fail mix → investigate |
| Stability | 3+ consecutive passes required |
| App bug | Mark test.fixme('BUG: desc') |
Error Recovery
| Error | Action |
|---|---|
| Timeout | Increase once → check selector → check if element renders |
| Element not found | Alternative locator → check DOM → verify page loaded |
| Network | Retry → consider mock → verify backend |
| Flaky | Explicit waits → check race conditions → run 5x |
| App bug | Mark test.fixme('BUG: desc') - test is skipped; CI usually still passes unless skipped tests fail the build |
CI Readiness Checklist
- Passes in CI runner mode:
<project e2e command> - Uses
process.env.BASE_URL - No hardcoded credentials
- Explicit viewport
Quick Reference
Always: accessible locators, unique test data, 3+ passes, mock external APIs
Never: waitForTimeout(), CSS selectors, test interdependencies, hardcoded creds
What ships with it
1 file 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 · 70 lines · 46 tokens per session scan A cadd978d8586
e2e-testing is a skill published in the GitHub repository JakubMikolajek/codex-skills-collection (6 stars, last pushed 19d ago), licensed MIT. It adds 46 tokens to every session and 509 once invoked, about $0.0002 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.
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