mcp-jest

mcp-jest

Automated testing for Model Context Protocol (MCP) servers. Test your AI agent tools with Jest-like syntax, validate protocol compliance, and integrate with CI/CD.

• 🧪 Test tools, resources, and prompts — automated validation of your MCP server capabilities
• 📦 Zero config — works out-of-the-box with any MCP server (stdio, HTTP, SSE)
• ✅ Protocol validation — check MCP compliance with detailed scoring
• 🚀 CI/CD ready — GitHub Actions, Jenkins, CircleCI integration
• 📸 Snapshot testing — capture and compare outputs over time

MIT licensed · npm · GitHub

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Install

npm install mcp-jest        # Project dependency
npm install -g mcp-jest     # Or globally for CLI

Use It

Test your MCP server in 30 seconds:

mcp-jest node ./server.js --tools search,email

Or use the JavaScript API:

import { mcpTest } from 'mcp-jest';

const results = await mcpTest(
  { command: 'node', args: ['./server.js'] },
  { tools: ['search', 'email'] }
);

console.log(`${results.passed}/${results.total} tests passed`);

What is MCP?

Model Context Protocol (MCP) is an open standard by Anthropic that lets AI assistants (Claude, ChatGPT, Gemini) connect to external tools, databases, and APIs. MCP-Jest tests those connections.

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Why MCP-Jest?

You built an MCP server. But how do you know it works?

• Manual testing is slow and error-prone
• Silent failures break AI workflows
• No native CI/CD integration for MCP
• Debugging production failures is hard

MCP-Jest solves this with automated, repeatable testing.

Features

Core Testing

• Automated Testing - Write tests once, run them everywhere
• Comprehensive Coverage - Test connections, tools, resources, and prompts
• Flexible Expectations - Simple strings or custom validation functions
• CI/CD Ready - Works with GitHub Actions, Jenkins, CircleCI, etc.

Advanced Features

• Snapshot Testing - Capture and compare MCP outputs over time
• Test Filtering - Run specific tests with --filter and --skip
• Watch Mode - Auto-rerun tests when files change
• HTML Reports - Generate beautiful, shareable test reports

Transport Support

• stdio - Default transport for local servers
• HTTP Streaming - Test remote HTTP servers
• SSE - Server-Sent Events support

Developer Tools

• Auto-Discovery - Automatically discover and generate tests for all capabilities
• Protocol Validator - Check MCP compliance with detailed scoring
• GitHub Action - Native CI/CD integration

CLI Quick Reference

Command	Description
mcp-jest node ./server.js --tools search	Test specific tools
mcp-jest --config test.json	Use config file
mcp-jest discover node ./server.js	Auto-discover capabilities
mcp-jest validate node ./server.js	Check protocol compliance
mcp-jest watch node ./server.js --tools search	Watch mode

Common Options

Option	Description
-t, --tools <tools>	Comma-separated tools to test
-c, --config <file>	Config file path
--timeout <ms>	Test timeout (default: 30000)
-u, --update-snapshots	Update snapshot files
--reporter html	Generate HTML report

See CLI Reference for all options.

Example: CI/CD Integration

# .github/workflows/test.yml
- name: Test MCP Server
  run: |
    npm install -g mcp-jest
    mcp-jest node ./dist/server.js --tools "search,analyze"

Example: Config File

{
  "server": {
    "command": "node",
    "args": ["./server.js"]
  },
  "tests": {
    "tools": {
      "search": {
        "args": { "query": "test" },
        "expect": "content.length > 0"
      }
    },
    "timeout": 30000
  }
}

Documentation

Guide	Description
Getting Started	Step-by-step setup guide
CLI Reference	Complete CLI documentation
API Reference	Library API documentation
Examples	Real-world examples
Architecture	How MCP-Jest works
Troubleshooting	Common issues and solutions

Feature Guides

• Snapshot Testing
• HTTP Transport
• GitHub Actions
• Watch Mode

Requirements

• Node.js 18+
• MCP Server implementing Model Context Protocol

Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

git clone https://github.com/josharsh/mcp-jest.git
cd mcp-jest
npm install
npm run dev
npm test

Security

See SECURITY.md for our security policy and vulnerability reporting.

Use Cases

MCP-Jest is ideal for:

• MCP Server Developers - Test your tools, resources, and prompts before deployment
• AI Application Teams - Ensure your MCP integrations work correctly
• DevOps/SRE - Add MCP server testing to CI/CD pipelines
• Open Source MCP Projects - Provide reliable testing for community contributions

Comparison with Other Tools

Feature	MCP-Jest	Manual Testing	Generic Test Frameworks
MCP Protocol Support	Native	Manual	Requires custom setup
Auto-Discovery	Yes	No	No
Snapshot Testing	Yes	No	Varies
Protocol Validation	Yes	No	No
CI/CD Integration	Built-in	Manual	Varies

Support

• GitHub Issues - Bug reports and feature requests
• GitHub Discussions - Questions and ideas
• Model Context Protocol - Official MCP documentation

Related Technologies

• Model Context Protocol (MCP) - The protocol standard
• @modelcontextprotocol/sdk - Official MCP SDK
• Claude - Anthropic's AI assistant with MCP support
• Jest - JavaScript testing framework (inspiration for MCP-Jest)

License

MIT License - Use freely in commercial and open source projects.

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Project Status

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Built for the MCP ecosystem | Documentation | Examples | Contributing

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