AI agent skill for Jest 29/30 — 28 rules: mocks, async, timers, snapshots, CI. Works with Claude Code, Cursor, Codex, Windsurf.

Jest Skill

An AI agent skill for writing, debugging, and reviewing Jest tests with modern best practices.

Created by Anivar Aravind

The Problem

AI agents frequently generate outdated or incorrect Jest patterns — wrong mock cleanup semantics (clearAllMocks vs restoreAllMocks), missing await on async assertions, incorrect timer mock usage, factory hoisting bugs, and anti-patterns that cause tests to silently pass without actually asserting anything. These produce test suites that compile and pass but don't test what they claim to test.

This Solution

28 rules with incorrect→correct code examples that teach agents Jest's actual API behavior, mock lifecycle, async patterns, timer control, module mocking, snapshot testing, configuration, and CI optimization. Each rule targets a specific mistake and shows exactly how to fix it.

Install

npx skills add anivar/jest-skill -g

Or with full URL:

npx skills add https://github.com/anivar/jest-skill

Baseline

• jest ^29.0.0 / ^30.0.0
• JavaScript / TypeScript

What's Inside

28 Rules Across 9 Categories

Each rule file contains:

• Why it matters
• Incorrect code with explanation
• Correct code with explanation
• Decision tables and additional context

9 Deep-Dive References