Unit Test MCP

Intelligent test generation and execution for GitHub Copilot

A VS Code extension that enables GitHub Copilot to generate, run, and improve Jest, Vitest, Pytest, and .NET tests using the Model Context Protocol (MCP).

✨ Features

• 🚀 Zero Setup: Install and use immediately - no configuration needed
• 🧪 Multi-Framework Support: Jest/Vitest (JS/TS), Pytest (Python), and .NET (C#)
• 🤖 AI-Powered: Works seamlessly with GitHub Copilot Chat
• 📊 Coverage Reports: Get instant test coverage feedback with inspect_coverage
• 📁 Batch Test Generation: Generate tests for entire folders at once with prioritization
• 🔧 Auto-Configuration: Automatically sets up MCP server on first activation
• 📝 Copilot Instructions: Auto-creates and syncs workspace instruction files that teach Copilot the test workflow
• 📖 Getting Started Walkthrough: Built-in tutorial accessible via Unit Test MCP: Show Welcome & Tutorial

📦 Installation

Install from the VS Code Marketplace or search for "Unit Test MCP" in the Extensions view (Ctrl+Shift+X).

🚀 Quick Start

1. Install the Extension

Install from the Marketplace link above. The extension auto-configures on first activation.

2. Start Using with Copilot

Open GitHub Copilot Chat and try:

Generate unit tests for this file

Generate tests for all files in src/

Run tests with coverage

What files have low coverage?

The extension will automatically activate and handle the requests.

📋 Requirements

🎯 What You Can Do

With Jest or Vitest (JavaScript/TypeScript)

• ✅ Generate JS/TS unit tests (including React component tests)
• ✅ Run tests with coverage
• ✅ Watch mode support
• ✅ Targeted test execution
• ✅ Update snapshots (Jest, via --updateSnapshot, when applicable)

With Pytest (Python)

• ✅ Generate Python unit tests
• ✅ Run tests with coverage
• ✅ Parametrized test support
• ✅ Fixture-based testing

With .NET (C#)

• ✅ Generate xUnit/NUnit tests
• ✅ Run tests via dotnet test
• ✅ Coverage reporting
• ✅ Solution-aware test generation

Coverage Reports

Ask Copilot "Run tests with coverage" or "What files have low coverage?" to get an interactive coverage report showing per-file line, branch, function, and statement coverage.

⚙️ Configuration

The extension works out-of-the-box, but you can customize it using the Unit Test MCP side panel.

1. Open the Unit Test MCP view in the VS Code sidebar (look for the clipboard/gear icon in the Activity Bar).
2. Use the UI to:
   • Browse and select custom instruction files for Jest, Vitest, Pytest, or .NET.
   • View currently loaded instructions.
   • Set target code coverage percentage.
   • Configure custom test commands.

Changes take effect immediately - no restart required!

📝 Custom Instructions

Customize test generation with your own instructions! See CUSTOM_INSTRUCTIONS.md for details.

💡 How It Works

┌─────────────────────────┐
│   GitHub Copilot Chat   │
└───────────┬─────────────┘
            │ MCP Protocol
┌───────────▼─────────────┐
│  TypeScript MCP Server  │
│  (Bundled in Extension) │
└───────────┬─────────────┘
            │
┌───────────▼─────────────┐
│ Jest / Vitest / Pytest  │
│        / Dotnet         │
└─────────────────────────┘

1. You ask Copilot to generate/run tests
2. Copilot calls the MCP server via standard protocol
3. Server executes Jest/Vitest/Pytest/.NET and returns results
4. Copilot shows you formatted output

🐛 Troubleshooting

Extension Not Working?

Check Status:

1. Open the Unit Test MCP sidebar view.
2. Verify that the server is connected and configuration is valid.

Still not working?

1. Reload VS Code: Ctrl+Shift+P → "Reload Window"
2. Check Output panel: View → Output → Select "Log (Extension Host)" and search for "Unit Test MCP"

Copilot Doesn't See the Tools?

1. Ensure GitHub Copilot extension is installed and active
2. Reload VS Code
3. Try asking: "What MCP tools are available?"

Tests Not Running?

For Jest:

• Ensure package.json exists in your project root
• Verify Jest is installed: npm list jest

For Vitest:

• Ensure package.json exists in your project root
• Verify Vitest is installed: npm list vitest

For Pytest:

• Ensure Python is installed: python --version
• Verify Pytest is installed: pip list | grep pytest

For .NET:

• Ensure .NET SDK is installed: dotnet --version
• Ensure your project is a valid .NET project

📚 Examples

Example 1: Generate React Tests

You: Generate unit tests for src/components/Button.tsx

Copilot: [Uses generate_test tool]
Creates: src/components/__tests__/Button.test.tsx

Example 2: Run Tests with Coverage

You: Run tests with coverage for the Button component

Copilot: [Uses run_tests tool]
Shows: Test results + coverage report

Example 3: Batch Test Generation

You: Generate tests for all files in src/services/

Copilot: [Uses generate_tests_batch tool]
Scans folder, prioritizes by missing tests/low coverage
Creates tests for each file sequentially

Example 4: Inspect Coverage

You: What files have low test coverage?

Copilot: [Uses inspect_coverage tool]
Shows: Worst-covered files and branches from existing coverage artifacts

🏗️ For Developers

See DEVELOPMENT.md for:

• Local development setup
• Building from source
• Testing the extension
• Publishing to Marketplace

📚 Additional Resources

🐳 Dev Container

This repository includes a pre-configured dev container with all necessary dependencies:

• Node.js & npm - For extension and MCP server development
• Python 3 & pip - For Pytest integration testing
• Git, ESLint, and common CLI tools - Pre-installed and ready to use

The dev container ensures consistent development environments across all contributors. Simply open in VS Code with the Remote-Containers extension installed.

🔧 Standalone MCP Server

The mcp-dist folder contains a standalone MCP server that works independently from the VS Code extension.

Use cases:

• Integration with other MCP clients (Claude Desktop, custom tools)
• Command-line test generation workflows
• CI/CD pipeline integration
• Copilot CLI with --additional-mcp-config

See mcp-dist/README.md for build and usage instructions.

🧪 Test Quality Evaluator Notebook

The notebooks/evaluator.ipynb demonstrates using GitHub Copilot CLI with the MCP server to automatically generate and evaluate tests.

Features:

• Integrates Copilot CLI with the standalone MCP server via --additional-mcp-config
• Generates test files using natural language prompts
• Evaluates test quality, coverage, and mutation scores
• Requires Python virtual environment and GitHub token with Copilot scope

See the notebook's first cell for complete setup instructions and available MCP tools.

�📄 License

MIT License - see LICENSE file for details

📮 Support

• Issues/Feedback: Use the "Give Feedback" button in the Unit Test MCP sidebar panel
• Repository: GitHub (Internal Microsoft access only)