Jest Generator

Generates Jest unit tests for JavaScript and TypeScript code with proper mocking, describe blocks, and coverage patterns. You get test files that follow the standard naming convention (Feature.test.tsx), include beforeEach/afterEach hooks for cleanup, and handle async testing, timers, and React components with Testing Library. The skill covers both bun and npm test runners, which is helpful since bun is faster but not everywhere yet. The structure templates are solid, especially the Arrange/Act/Assert pattern and the common matchers reference. Honestly, this is most useful when you need to backfill tests on existing code or want consistent test structure across a codebase without remembering every Jest API detail.

skills.sh installs: 391
GitHub stars: 248
last updated: Aug 21, 2026

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Install

$ npx -y skills add secondsky/claude-skills --skill jest-generator --agent claude-code

Installs into .claude/skills of the current project.

Files

Jest Generator Skill

Purpose

Generate Jest-based unit tests for JavaScript and TypeScript code, following Jest conventions and best practices with proper mocking, describe blocks, and code organization.

When to Use

Generate Jest tests for JavaScript/TypeScript modules
Create test files for React components
Add missing test coverage to existing code
Need Jest-specific patterns (mocks, spies, snapshots)

Test File Naming

Source to Test Mapping:

src/components/Feature.tsx → src/components/Feature.test.tsx
src/utils/validator.ts → src/utils/validator.test.ts
src/models/User.ts → src/models/User.test.ts

Running Tests

# Preferred: Using bun (faster)
bun test

# Run specific file
bun test src/utils/validator.test.ts

# Run with coverage
bun test --coverage

# Watch mode
bun test --watch

# Alternative: Using npm
npm test
npm test -- --coverage

Jest Test Structure

import { functionToTest, ClassToTest } from './Feature'

jest.mock('./dependency')

describe('ModuleName', () => {
  beforeEach(() => {
    jest.clearAllMocks()
  })

  afterEach(() => {
    jest.restoreAllMocks()
  })

SKILL.md on GitHub