End-to-End Testing

End-to-End Testing is a skill for Claude Code, Codex from niels-emmer/myace. It costs 28 tokens per session (280 once invoked), scanned A, original, MIT.

A guide to end-to-end (E2E) tests, which check complete user journeys across the frontend, backend, and test environment.

In plain words
What is it for?
Use it to test journeys such as login, create/update/delete actions, and error paths, including in continuous integration (CI).
Why use it?
It catches integration bugs that tests of individual parts can miss and helps reduce flaky, unreliable results.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for aider. Also seen: mentions Codex; built for aider; mentions OpenCode.

Good fit Use it to test journeys such as login, create/update/delete actions, and error paths, including in continuous integration (CI).

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Install with agentmods
npx agentmods add skills/niels-emmer/myace/end-to-end-testing
Install

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.

Any agent
npx skills add niels-emmer/myace --skill end-to-end-testing
Clone the repo
git clone --depth 1 https://github.com/niels-emmer/myace

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for End-to-End Testing

README.md
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Your own site
<a href="https://agentmods.dev/skills/niels-emmer/myace/end-to-end-testing"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/end-to-end-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.

agentmods 80×15 button for End-to-End Testing

Your own site · 80×15
<a href="https://agentmods.dev/skills/niels-emmer/myace/end-to-end-testing"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/end-to-end-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 280 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00028 $0.00280
Opus 5 $0.00014 $0.00140
Sonnet 5 $0.00006 $0.00056
Haiku 4.5 $0.00003 $0.00028

Measured 7d ago against content hash 9a1a96201eba, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

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 7d 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.

collections/additional/fullstack/skills/end-to-end-testing/SKILL.md · 29 lines

What it actually says

Purpose

Catch integration bugs that layer-isolated tests miss.

When to use it

For every feature that spans frontend and backend.

Checklist

  • Scope: test critical user journeys (login, CRUD, error paths) — not every UI permutation.
  • Structure: use page objects or fixtures for maintainable test code.
  • Environment: dedicated test database, clean state per test run.
  • Data seeding: set up test data as part of the test, not in shared fixtures.
  • Flakiness prevention: use wait strategies for async operations, retry on transient failures.
  • CI integration: run E2E tests in CI, not just locally. Fail the build on E2E failures.

Expected output

A suite of E2E tests covering the critical paths of each feature, running in CI with reliable pass/fail results.

Changes

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.

  1. 7d ago First seen · 29 lines · 28 tokens per session scan A 9a1a96201eba

Subscribe to this mod's changes

End-to-End Testing is a skill published in the GitHub repository niels-emmer/myace (1 stars, last pushed 4d ago), licensed MIT. It adds 28 tokens to every session and 280 once invoked, about $0.0001 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 2026-09-03.