MCP Server E2E Testing Example

A minimal example repository demonstrating two patterns for end‑to‑end (E2E) testing a TypeScript MCP (Model Context Protocol) server using Vitest:

• Raw approach: Spawning the CLI with tsx and communicating over stdio (JSON‑RPC).
• SDK approach: Using the official MCP SDK’s Client and InMemoryTransport for in‑memory RPC.

Repository: https://github.com/mkusaka/mcp-server-e2e-testing-example

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📁 Repository Layout

.
├── LICENSE
├── README.md
├── package.json
├── pnpm-lock.yaml
├── src
│   ├── cli.ts         # CLI entrypoint (tsx + stdio transport)
│   └── server.ts      # createServer() factory (resources, prompts, tools)
├── tests
│   └── e2e
│       ├── raw.spec.ts  # spawn‑based E2E tests
│       └── sdk.spec.ts  # SDK/InMemoryTransport‑based E2E tests
└── tsconfig.json

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🚀 Getting Started

Prerequisites

• Node.js ≥ 16
• pnpm installed globally
• Git

Installation

# Clone the repo
git clone https://github.com/mkusaka/mcp-server-e2e-testing-example.git
cd mcp-server-e2e-testing-example

# Install dependencies
pnpm install

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🧪 Running E2E Tests

1. Raw (spawn + stdio) tests

This suite launches the CLI (src/cli.ts) via npx tsx and sends JSON‑RPC over stdin/stdout.

pnpm vitest run tests/e2e/raw.spec.ts

2. SDK (in‑memory) tests

This suite uses the MCP SDK’s Client + InMemoryTransport to invoke the same server logic without spawning a child process.

pnpm vitest run tests/e2e/sdk.spec.ts

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🛠️ Scripts

Add these to package.json if desired:

{
  "scripts": {
    "test:raw": "vitest run tests/e2e/raw.spec.ts",
    "test:sdk": "vitest run tests/e2e/sdk.spec.ts",
    "test": "vitest run"
  }
}

• pnpm run test:raw – Run only the raw/stdio tests
• pnpm run test:sdk – Run only the in‑memory SDK tests
• pnpm run test – Run all tests

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📦 Publishing & Usage

This repository is intended as an example/template. Feel free to:

• Adapt the src/server.ts factory for your own MCP server
• Expand raw.spec.ts and sdk.spec.ts with additional test cases
• Integrate into your CI pipeline

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📄 License

Released under the MIT License.