MCP Mock Client

Create mock MCP client for server testing.

Generated Patterns

import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';
import { spawn } from 'child_process';

export async function createTestClient(serverCmd: string, args: string[]) {
  const proc = spawn(serverCmd, args, { stdio: ['pipe', 'pipe', 'inherit'] });
  const transport = new StdioClientTransport({ reader: proc.stdout!, writer: proc.stdin! });
  const client = new Client({ name: 'test-client', version: '1.0.0' }, { capabilities: {} });
  await client.connect(transport);
  return { client, close: () => proc.kill() };
}

export async function testTool(client: Client, name: string, args: Record<string, unknown>) {
  const result = await client.callTool({ name, arguments: args });
  return result;
}

Target Processes

• mcp-server-testing-suite
• mcp-tool-implementation