🧪 JestSmith

🧠💥 Auto-generate Jest test cases for your JavaScript/TypeScript code using AI — so you can ship confidently without writing a single test.

🚀 What is JestSmith?

JestSmith is a CLI tool that uses AI to automatically generate Jest test cases for any JavaScript or TypeScript project, including:

• ✅ React components
• ✅ Node.js backend logic
• ✅ NestJS modules (controllers, services, routes)
• ✅ Any framework or custom business logic

✨ Features

• ⚡ One-command test generation
• 📂 Folder support (generate tests for entire modules)
• 🧠 AI-powered (works better with a short explanation)
• 📝 Outputs clean, readable, idiomatic Jest tests
• 🧰 Framework-agnostic (React, Node, Angular, NestJS, etc.)
• 🛠️ TypeScript-native

📦 Installation

npm install -g jestsmith

🧑‍💻 Usage

1. Add your OpenAI API_KEY

export OPENAI_API_KEY=<Your OpenAI API KEY>

Or

Add this to your project's local .env file:

OPENAI_API_KEY=<Your OpenAI API KEY>

2. Generate test for a single file

jestsmith ./src/components/LoginForm.tsx --describe "A login form with Formik + Yup that hits a login API on submit"

3. Generate test for a whole folder (e.g., a NestJS module)

jestsmith ./src/modules/user --describe "This is a NestJS User module with CRUD operations"

✅ The tool will:

• Parse each file
• Understand file relationships (controllers, services, routes)
• Generate relevant Jest test cases into a __tests__/ folder or in the --out-dir

🛠 CLI Options

| Option | Description | | ------------ | --------------------------------------------------------- | | --describe | (optional) Add context so the AI writes better tests | | --outDir | (optional) Customize the output folder for test files | | --dry-run | (coming soon) Preview the generated output without saving |

📁 Example

Given a file like:

// LoginForm.tsx
const LoginForm = () => {
  const formik = useFormik({
    /* yup validation */
  });

  const handleSubmit = async () => {
    await api.login(formik.values);
  };

  return <form onSubmit={handleSubmit}>...</form>;
};

Running:

jestsmith LoginForm.tsx --describe "React login form using Formik and Yup"

Might generate:

// __tests__/LoginForm.test.tsx
import { render, fireEvent } from '@testing-library/react';
import LoginForm from '../LoginForm';

describe('LoginForm', () => {
  it('calls login API on successful form submission', async () => {
    ...
  });
});

📚 How It Works

Under the hood, JestSmith:

1. Uses AST parsing to understand your code structure
2. Sends intelligently prepared prompts to an LLM (like GPT)
3. Applies Jest syntax best practices
4. Writes test files based on your code and explanation

💡 Tips for Best Results

• ✅ Provide a short --describe for context
• ✅ Keep functions/components modular and clean
• ✅ Use TypeScript where possible for better inference
• ✅ Use meaningful function/component names

🤖 Roadmap

• [ ] --dry-run to preview generated code
• [ ] Support .jestsmithrc config files
• [ ] Built-in Prettier formatting
• [ ] Estimate test coverage based on function count
• [ ] VSCode extension support

🧑‍🎤 Contributing

PRs, ideas, and contributions are welcome!

🔧 Local Dev

# clone the repo
git clone https://github.com/ahsansheikh94/jestsmith.git
cd jestsmith

# install deps
npm install

# build the CLI
npm run build

# test locally
node dist/bin/index.js ./src/example.ts --describe "Login form with API call"

📦 Publishing

This repo uses Changesets for automated versioning + changelogs + npm publishing.

To release:

npx changeset       # describe the change
git commit -am "chore: version bump"
git push

GitHub Actions will:

• Create a release PR
• Tag version
• Publish to npm automatically

You’ll need to set NPM_TOKEN in GitHub Secrets.

🪪 License

MIT © Ahsan Sheikh

🌍 Community

Found a bug? Have feature ideas?
→ Open an issue

Love the tool?
→ ⭐ Star it and share it with your team!