javascript-testing-patterns

javascript-testing-patterns is a skill for Claude Code, Codex from beel-collab/presets.dev. It costs 23 tokens per session (332 once invoked), scanned A, a copy of javascript-testing-patterns, MIT.

A guide to testing JavaScript and TypeScript applications, from individual functions to complete user journeys.

In plain words
What is it for?
Use it to set up tests, write unit and integration tests, test frontend components and APIs, mock dependencies, and apply TDD, a practice of writing tests before implementation.
Why use it?
It helps catch regressions and verify that application code, APIs, components, integrations, and external-service interactions behave as expected.

Skill for Claude CodeCodex

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

Good fit Use it to set up tests, write unit and integration tests, test…

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Install with agentmods
npx agentmods add skills/beel-collab/presets.dev/javascript-testing-patterns
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 beel-collab/presets.dev --skill javascript-testing-patterns
Clone the repo
git clone --depth 1 https://github.com/beel-collab/presets.dev

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 javascript-testing-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/beel-collab/presets.dev/javascript-testing-patterns.svg)](https://agentmods.dev/skills/beel-collab/presets.dev/javascript-testing-patterns)
Your own site
<a href="https://agentmods.dev/skills/beel-collab/presets.dev/javascript-testing-patterns"><img src="https://agentmods.dev/badge/skills/beel-collab/presets.dev/javascript-testing-patterns.svg" alt="Measured on agentmods" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 332 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 91% copy Near-identical to another mod 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 $0.00023 $0.00332
Opus 5 $0.00012 $0.00166
Sonnet 5 $0.00005 $0.00066
Haiku 4.5 $0.00002 $0.00033

Measured 3d ago against content hash 7361effe1854, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

javascript-testing-patterns 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 3d 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.

Origin

This is a copy

91% identical to javascript-testing-patterns — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

claude/skills/development/javascript-testing-patterns/SKILL.md · 45 lines

What it actually says

JavaScript Testing Patterns

Comprehensive guide for implementing robust testing strategies in JavaScript/TypeScript applications using modern testing frameworks and best practices.

Use this skill when

  • Setting up test infrastructure for new projects
  • Writing unit tests for functions and classes
  • Creating integration tests for APIs and services
  • Implementing end-to-end tests for user flows
  • Mocking external dependencies and APIs
  • Testing React, Vue, or other frontend components
  • Implementing test-driven development (TDD)
  • Setting up continuous testing in CI/CD pipelines

Do not use this skill when

  • The task is unrelated to javascript testing patterns
  • You need a different domain or tool outside this scope

Instructions

  • Clarify goals, constraints, and required inputs.
  • Apply relevant best practices and validate outcomes.
  • Provide actionable steps and verification.
  • If detailed examples are required, open resources/implementation-playbook.md.

Resources

  • resources/implementation-playbook.md for detailed patterns and examples.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
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. 3d ago First seen · 45 lines · 23 tokens per session scan A 7361effe1854

Subscribe to this mod's changes

javascript-testing-patterns is a skill published in the GitHub repository beel-collab/presets.dev (2 stars, last pushed 4mo ago), licensed MIT. It adds 23 tokens to every session and 332 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to javascript-testing-patterns, differing in 11 lines, and is treated as a copy.