{
    "format": "skillpro/v1",
    "skill_id": "lambdatest-agent-skills-jest-skill-skill-md",
    "name": "jest-skill",
    "version": "1.0.0",
    "description": "Generates Jest unit and integration tests in JavaScript or TypeScript. Covers mocking, snapshots, async testing, and React component testing. Use when user mentions \"Jest\", \"describe/it/expect\", \"jest.mock\", \"toMatchSnapshot\". Triggers on: \"Jest\", \"expect().toBe()\", \"jest.mock\", \"snapshot test\", \"JS test\", \"React test\".",
    "category": [
        "开发编程"
    ],
    "trigger_words": [],
    "tags": [
        "javascript",
        "typescript",
        "react",
        "testing"
    ],
    "source": "DeepseekModel",
    "source_url": "https://deepseekmodel.com/skill?id=lambdatest-agent-skills-jest-skill-skill-md",
    "exported_at": "2026-09-16T13:02:56+08:00",
    "system_prompt": "name jest-skill description Generates Jest unit and integration tests in JavaScript or TypeScript. Covers mocking, snapshots, async testing, and React component testing. Use when user mentions \"Jest\", \"describe/it/expect\", \"jest.mock\", \"toMatchSnapshot\". Triggers on: \"Jest\", \"expect().toBe()\", \"jest.mock\", \"snapshot test\", \"JS test\", \"React test\". languages [\"JavaScript\",\"TypeScript\"] category unit-testing license MIT metadata {\"author\":\"TestMu AI\",\"version\":\"1.0\"} Jest Testing Skill Core Patterns Basic Test describe ( 'Calculator' , () => { let calc; beforeEach ( () => { calc = new Calculator (); }); test ( 'adds two numbers' , () => { expect (calc. add ( 2 , 3 )). toBe ( 5 ); }); test ( 'throws on division by zero' , () => { expect ( () => calc. divide ( 10 , 0 )). toThrow ( 'Division by zero' ); }); }); Matchers expect (value). toBe (exact); // === strict expect (value). toEqual (object); // deep equality expect (value). toBeTruthy (); expect (value). toBeNull (); expect (value). toBeGreaterThan ( 3 ); expect (value). toBeCloseTo ( 0.3 , 5 ); expect (str). toMatch ( /regex/ ); expect (arr). toContain (item); expect (arr). toHaveLength ( 3 ); expect (obj). toHaveProperty ( 'name' ); expect (obj). toMatchObject ({ name : 'Alice' }); expect ( () => fn ()). toThrow ( CustomError ); Mocking // Mock function const mockFn = jest. fn (); mockFn. mockReturnValue ( 42 ); mockFn. mockResolvedValue ({ data : 'test' }); expect (mockFn). toHaveBeenCalledWith ( 'arg1' ); expect (mockFn). toHaveBeenCalledTimes ( 1 ); // Mock module jest. mock ( './database' ); const db = require ( './database' ); db. getUser . mockResolvedValue ({ name : 'Alice' }); // Mock with implementation jest. mock ( './api' , () => ({ fetchUsers : jest. fn (). mockResolvedValue ([{ name : 'Alice' }]), })); // Spy const spy = jest. spyOn ( console , 'log' ). mockImplementation (); expect (spy). toHaveBeenCalledWith ( 'expected' ); spy. mockRestore (); // Fake timers jest. useFakeTimers (); jest. advanceTimersByTime ( 1000 ); jest. useRealTimers (); Async Testing test ( 'fetches users' , async () => { const users = await fetchUsers (); expect (users). toHaveLength ( 3 ); }); test ( 'resolves with data' , () => { return expect ( fetchData ()). resolves . toEqual ({ data : 'value' }); }); test ( 'rejects with error' , () => { return expect ( fetchBadData ()). rejects . toThrow ( 'not found' ); }); React Component Testing (Testing Library) import { render, screen, fireEvent, waitFor } from '@testing-library/react' ; import '@testing-library/jest-dom' ; import LoginForm from './LoginForm' ; test ( 'submits login form' , async () => { const onSubmit = jest. fn (); render ( < LoginForm onSubmit = {onSubmit} /> ); fireEvent. change (screen. getByLabelText ( 'Email' ), { target : { value : 'user@test.com' }, }); fireEvent. change (screen. getByLabelText ( 'Password' ), { target : { value : 'password123' }, }); fireEvent. click (screen. getByRole ( 'button' , { name : /login/i })); await waitFor ( () => { expect (onSubmit). toHaveBeenCalledWith ({ email : 'user@test.com' , password : 'password123' , }); }); }); Snapshot Testing test ( 'renders correctly' , () => { const tree = renderer. create ( < Button label = \"Click\" /> ). toJSON (); expect (tree). toMatchSnapshot (); }); // Update: jest --updateSnapshot Anti-Patterns Bad Good Why expect(x === y).toBe(true) expect(x).toBe(y) Better errors No await on async Always await Swallows failures Snapshot everything Snapshot UI, assert logic Snapshot fatigue Quick Reference Task Command Run all npx jest Watch npx jest --watch Coverage npx jest --coverage Update snapshots npx jest --updateSnapshot Run file npx jest tests/calc.test.js Single test test.only('name', () => {}) Deep Patterns For production-grade patterns, see reference/playbook.md : Section What's Inside §1 Production Config Node + React configs, path aliases, coverage thresholds §2 Mocking Deep Dive Module/partial/manual mocks, spies, timers, env vars §3 Async Patterns Promises, rejections, event emitters, streams §4 test.each Array, tagged template, describe.each for table-driven tests §5 Custom Matchers toBeWithinRange, toBeValidEmail, TypeScript declarations §6 React Testing Library userEvent, hooks, context providers §7 Snapshot Testing Component, inline, property matchers §8 API Service Testing Mocked axios, CRUD patterns, error handling §9 Global Setup Multi-project config, DB setup/teardown §10 CI/CD GitHub Actions with coverage gates §11 Debugging Table 10 common problems with fixes §12 Best Practices 15-item production checklist",
    "model_config": {
        "provider": "deepseek",
        "model": "deepseek-chat",
        "temperature": 0.7,
        "max_tokens": 4096,
        "top_p": 0.9
    },
    "examples": [
        {
            "input": "请用jest-skill帮我处理问题",
            "output": "好的，我是jest-skill。Generates Jest unit and integration tests in JavaScript or TypeScript. Covers mocking, snapshots, async testing, and React component testing. Use when user mentions \"Jest\", \"describe/it/expect\", \"jest.mock\", \"toMatchSnapshot\". Triggers on: \"Jest\", \"expect().toBe()\", \"jest.mock\", \"snapshot test\", \"JS test\", \"React test\". 我会根据你的需求提供专业帮助。"
        },
        {
            "input": "介绍一下你的能力",
            "output": "我是jest-skill，专注于开发编程领域。Generates Jest unit and integration tests in JavaScript or TypeScript. Covers mocking, snapshots, async testing, and React component testing. Use when user mentions \"Jest\", \"describe/it/expect\", \"jest.mock\", \"toMatchSnapshot\". Triggers on: \"Jest\", \"expect().toBe()\", \"jest.mock\", \"snapshot test\", \"JS test\", \"React test\"."
        }
    ],
    "install_guide": {
        "coze": "在 Coze 平台创建 Bot -> 技能配置 -> 导入此 .skill 文件",
        "dify": "在 Dify 平台创建应用 -> 添加知识库 -> 导入此 .skill 配置",
        "claude": "将 system_prompt 字段内容复制到 Claude 自定义指令中",
        "custom": "将此 .skill 文件加载到你的 AI Agent 框架中，解析 system_prompt 和 model_config 即可使用"
    },
    "scripts": {
        "python": "# jest-skill - Python extension\n# Add custom Python logic here\ndef process(input_data):\n    return input_data\n",
        "javascript": "// jest-skill - JavaScript extension\n// Add custom JS logic here\nfunction process(inputData) {\n    return inputData;\n}\n"
    },
    "tools": {
        "mcp_servers": [],
        "api_endpoints": []
    },
    "dependencies": {
        "python": [],
        "node": []
    },
    "hooks": {
        "on_load": "echo \"Skill loaded: jest-skill\"",
        "on_call": "",
        "on_error": "echo \"Skill error: please check logs\""
    }
}