test-mcp-logging.ts•3.63 kB
#!/usr/bin/env node
/**
* Test script to verify MCP logging doesn't corrupt the protocol
* This script tests that all logging goes to stderr and not stdout
*/
import { spawn } from 'child_process';
import { writeFileSync, mkdirSync, rmSync } from 'fs';
import { join } from 'path';
console.log('🧪 Testing MCP Server Logging');
console.log('============================');
// Create a temporary test directory
const testDir = join(process.cwd(), '.test-mcp-logging');
mkdirSync(testDir, { recursive: true });
// Test 1: Verify server starts without stdout pollution
console.log('\n📋 Test 1: Server Startup (with logging)');
console.log('----------------------------------------');
const serverProcess = spawn('node', ['dist/src/index.js'], {
env: {
...process.env,
PROJECT_PATH: testDir,
LOG_LEVEL: 'DEBUG', // Enable all logging levels
},
stdio: ['pipe', 'pipe', 'pipe'] // stdin, stdout, stderr
});
let stdoutData = '';
let stderrData = '';
let jsonResponseReceived = false;
// Capture stdout (should only contain JSON-RPC messages)
serverProcess.stdout.on('data', (data) => {
stdoutData += data.toString();
// Try to parse as JSON-RPC
const lines = data.toString().split('\n').filter(line => line.trim());
for (const line of lines) {
try {
const parsed = JSON.parse(line);
if (parsed.jsonrpc === '2.0') {
jsonResponseReceived = true;
console.log('✅ Valid JSON-RPC response received on stdout');
}
} catch (e) {
if (line.trim()) {
console.error('❌ Non-JSON data on stdout:', line);
console.error(' This will corrupt the MCP protocol!');
}
}
}
});
// Capture stderr (should contain all logging)
serverProcess.stderr.on('data', (data) => {
stderrData += data.toString();
});
// Send a test JSON-RPC request
const testRequest = {
jsonrpc: '2.0',
id: 1,
method: 'initialize',
params: {
protocolVersion: '0.1.0',
capabilities: {},
clientInfo: {
name: 'test-client',
version: '1.0.0'
}
}
};
// Send request after a short delay to ensure server is ready
setTimeout(() => {
serverProcess.stdin.write(JSON.stringify(testRequest) + '\n');
}, 500);
// Give the server time to respond
setTimeout(() => {
serverProcess.kill();
console.log('\n📊 Results:');
console.log('----------');
// Check if logging appeared on stderr
if (stderrData.includes('[INFO]') || stderrData.includes('[DEBUG]')) {
console.log('✅ Logging correctly sent to stderr');
console.log(' Sample stderr output:', stderrData.split('\\n')[0]);
} else {
console.log('⚠️ No logging detected on stderr');
}
// Check if stdout is clean
const nonJsonLines = stdoutData.split('\n').filter(line => {
if (!line.trim()) return false;
try {
JSON.parse(line);
return false;
} catch {
return true;
}
});
if (nonJsonLines.length === 0 && jsonResponseReceived) {
console.log('✅ stdout contains only valid JSON-RPC messages');
} else if (nonJsonLines.length > 0) {
console.error('❌ stdout contains non-JSON data:');
nonJsonLines.forEach(line => console.error(' ', line));
} else {
console.log('⚠️ No JSON-RPC response received');
}
// Cleanup
rmSync(testDir, { recursive: true, force: true });
console.log('\n✨ Test complete');
process.exit(nonJsonLines.length > 0 ? 1 : 0);
}, 2000);
// Handle errors
serverProcess.on('error', (error) => {
console.error('❌ Failed to start server:', error);
rmSync(testDir, { recursive: true, force: true });
process.exit(1);
});