// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) 2025 Pierre Fitness Intelligence
// ABOUTME: Mock MCP client for testing bridge stdio communication
// ABOUTME: Simulates Claude Desktop's MCP Client behavior over stdin/stdout
//
// Licensed under either of Apache License, Version 2.0 or MIT License at your option.
// Copyright ©2025 Async-IO.org
const { spawn } = require('child_process');
const { EventEmitter } = require('events');
/**
* Mock MCP client that communicates via stdio
* Simulates MCP Client behavior
*/
class MockMCPClient extends EventEmitter {
constructor(command, args = []) {
super();
this.command = command;
// ALWAYS add --no-browser to prevent 100+ Chrome tabs opening during tests
this.args = args.includes('--no-browser') ? args : [...args, '--no-browser'];
this.process = null;
this.buffer = '';
this.pendingRequests = new Map();
this.nextId = 1;
}
async start() {
return new Promise((resolve, reject) => {
this.process = spawn(this.command, this.args, {
stdio: ['pipe', 'pipe', 'pipe']
});
this.process.on('error', (error) => {
reject(new Error(`Failed to start bridge: ${error.message}`));
});
this.process.stdout.on('data', (data) => {
this.handleData(data.toString());
});
this.process.stderr.on('data', (data) => {
if (process.env.DEBUG) {
console.error(`[Bridge Stderr]: ${data}`);
}
});
this.process.on('exit', (code) => {
if (code !== 0 && code !== null) {
this.emit('error', new Error(`Bridge exited with code ${code}`));
}
});
// Wait a moment for bridge to initialize
setTimeout(resolve, 1000);
});
}
handleData(data) {
this.buffer += data;
const lines = this.buffer.split('\n');
this.buffer = lines.pop() || '';
for (const line of lines) {
if (line.trim()) {
try {
const message = JSON.parse(line);
this.handleMessage(message);
} catch (error) {
console.error('Failed to parse JSON:', line);
}
}
}
}
handleMessage(message) {
if (message.id !== undefined && this.pendingRequests.has(message.id)) {
const { resolve, reject, timeout } = this.pendingRequests.get(message.id);
clearTimeout(timeout);
this.pendingRequests.delete(message.id);
if (message.error) {
reject(new Error(message.error.message || JSON.stringify(message.error)));
} else {
resolve(message);
}
} else {
this.emit('notification', message);
}
}
async send(request, timeoutMs = 30000) {
if (!this.process) {
throw new Error('Client not started');
}
const id = request.id || this.nextId++;
const fullRequest = { ...request, id, jsonrpc: '2.0' };
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
this.pendingRequests.delete(id);
reject(new Error(`Request ${id} timed out after ${timeoutMs}ms`));
}, timeoutMs);
this.pendingRequests.set(id, { resolve, reject, timeout });
this.process.stdin.write(JSON.stringify(fullRequest) + '\n');
});
}
sendRaw(data) {
return new Promise((resolve) => {
let response = '';
const originalHandler = this.handleData.bind(this);
this.handleData = (data) => {
response += data;
if (response.includes('\n')) {
this.handleData = originalHandler;
resolve(response.trim());
}
};
this.process.stdin.write(data);
});
}
async stop() {
if (this.process) {
return new Promise((resolve) => {
this.process.on('exit', resolve);
this.process.kill('SIGTERM');
setTimeout(() => {
if (!this.process.killed) {
this.process.kill('SIGKILL');
}
resolve();
}, 5000);
});
}
}
}
module.exports = { MockMCPClient };
