frontend-testing

frontend-testing is a skill for Claude Code, Codex from bestdeejay-design/agent-skills. It costs 243 tokens per session (2,921 once invoked), scanned A, original, MIT.

A front-end testing guide and scaffolding skill covering unit, integration, end-to-end, visual, accessibility, browser, device, performance, mutation, monitoring, coverage, mocking, and contract tests.

In plain words
What is it for?
Use it to decide which testing layer should cover each concern, create test setup for tools such as Vitest, Jest, MSW, and Playwright, and connect tests to continuous integration.
Why use it?
It turns production-readiness expectations into specific tests and configurations instead of leaving testing as a vague final step.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to decide which testing layer should cover each concern, create test setup for tools such as Vitest, Jest, MSW, and Playwright, and connect tests to continuous integration.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/bestdeejay-design/agent-skills/frontend-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 bestdeejay-design/agent-skills --skill frontend-testing
Clone the repo
git clone --depth 1 https://github.com/bestdeejay-design/agent-skills

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 frontend-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/bestdeejay-design/agent-skills/frontend-testing.svg)](https://agentmods.dev/skills/bestdeejay-design/agent-skills/frontend-testing)
Your own site
<a href="https://agentmods.dev/skills/bestdeejay-design/agent-skills/frontend-testing"><img src="https://agentmods.dev/badge/skills/bestdeejay-design/agent-skills/frontend-testing.svg" alt="Measured on agentmods" height="20"></a>
Per session 243 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,921 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 $0.00243 $0.02921
Opus 5 $0.00121 $0.01460
Sonnet 5 $0.00049 $0.00584
Haiku 4.5 $0.00024 $0.00292

Measured 7d ago against content hash 10fd0904261e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

frontend-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.

The scan reads SKILL.md. This mod also ships 3 executable files (references/e2e-smoke.spec.ts, references/playwright.config.ts, scripts/scaffold.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/frontend-testing/SKILL.md · 203 lines

How it starts

The opening of the file, as written. The whole thing — 203 lines — stays where its author put it; the contents beside it link to each section on GitHub.

frontend-testing

Define and scaffold frontend testing for production readiness. Our other frontend skills (frontend-perfection, frontend-a11y, frontend-performance) audit a built site; they run ZERO tests. This skill closes that gap: it tells you what to test, which layer owns each concern, and hands you the config to wire into CI. It is a process/knowledge + scaffolding skill, not a runtime audit.

The 13 Testing rules → pyramid layer

Mapped 1:1 from the Front-End-Checklist "Testing" category. Each rule names the layer it belongs to and the reference file that scaffolds it.

# Rule (verbatim priority) Layer Scaffold
1 Write unit tests [High] Unit your unit runner (Vitest/Jest)
2 Write integration tests for key workflows [High] Integration your runner + MSW
3 Implement end-to-end testing [High] E2E references/playwright.config.ts, references/e2e-smoke.spec.ts
4 Use visual regression testing [Medium] Visual references/visual-regression.md
5 Include accessibility testing [High] A11y references/a11y-test.md
6 Test across all major browsers [High] Cross-browser references/playwright.config.ts (projects)
7 Test on real mobile devices and viewports [High] Real-device references/playwright.config.ts (Mobile projects)
8 Enforce performance budgets in CI [Medium] Perf-budget references/ci-perf-budget.yml
9 Use mutation testing to measure how well tests detect bugs [Medium] Mutation Stryker config note
10 Integrate real-time error monitoring in production [High] Error-monitoring Sentry note
11 Maintain test coverage thresholds [Medium] Coverage references/ci-perf-budget.yml (coverage gate)
12 Follow mocking best practices [Medium] Mocking mocking note
13 Implement consumer-driven contract testing for API boundaries [Medium] Contract references/contract-test.md

Testing pyramid (shape, not just a list)

Read the full file on GitHub · 203 lines

Files

What ships with it

8 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.

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 · 203 lines · 243 tokens per session scan A 10fd0904261e

Subscribe to this mod's changes

frontend-testing is a skill published in the GitHub repository bestdeejay-design/agent-skills (5 stars, last pushed 3d ago), licensed MIT. It adds 243 tokens to every session and 2,921 once invoked, about $0.0012 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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