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/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
/**
* This test verifies MCP (Model Context Protocol) server integration.
* It uses a minimal MCP server implementation that doesn't require
* external dependencies, making it compatible with Docker sandbox mode.
*/
import { test, describe, before } from 'node:test';
import { strict as assert } from 'node:assert';
import { TestRig, validateModelOutput } from './test-helper.js';
import { join } from 'path';
import { writeFileSync } from 'fs';
// Create a minimal MCP server that doesn't require external dependencies
// This implements the MCP protocol directly using Node.js built-ins
const serverScript = `#!/usr/bin/env node
/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
const readline = require('readline');
const fs = require('fs');
// Debug logging to stderr (only when MCP_DEBUG or VERBOSE is set)
const debugEnabled = process.env.MCP_DEBUG === 'true' || process.env.VERBOSE === 'true';
function debug(msg) {
if (debugEnabled) {
fs.writeSync(2, \`[MCP-DEBUG] \${msg}\\n\`);
}
}
debug('MCP server starting...');
// Simple JSON-RPC implementation for MCP
class SimpleJSONRPC {
constructor() {
this.handlers = new Map();
this.rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: false
});
this.rl.on('line', (line) => {
debug(\`Received line: \${line}\`);
try {
const message = JSON.parse(line);
debug(\`Parsed message: \${JSON.stringify(message)}\`);
this.handleMessage(message);
} catch (e) {
debug(\`Parse error: \${e.message}\`);
}
});
}
send(message) {
const msgStr = JSON.stringify(message);
debug(\`Sending message: \${msgStr}\`);
process.stdout.write(msgStr + '\\n');
}
async handleMessage(message) {
if (message.method && this.handlers.has(message.method)) {
try {
const result = await this.handlers.get(message.method)(message.params || {});
if (message.id !== undefined) {
this.send({
jsonrpc: '2.0',
id: message.id,
result
});
}
} catch (error) {
if (message.id !== undefined) {
this.send({
jsonrpc: '2.0',
id: message.id,
error: {
code: -32603,
message: error.message
}
});
}
}
} else if (message.id !== undefined) {
this.send({
jsonrpc: '2.0',
id: message.id,
error: {
code: -32601,
message: 'Method not found'
}
});
}
}
on(method, handler) {
this.handlers.set(method, handler);
}
}
// Create MCP server
const rpc = new SimpleJSONRPC();
// Handle initialize
rpc.on('initialize', async (params) => {
debug('Handling initialize request');
return {
protocolVersion: '2024-11-05',
capabilities: {
tools: {}
},
serverInfo: {
name: 'addition-server',
version: '1.0.0'
}
};
});
// Handle tools/list
rpc.on('tools/list', async () => {
debug('Handling tools/list request');
return {
tools: [{
name: 'add',
description: 'Add two numbers',
inputSchema: {
type: 'object',
properties: {
a: { type: 'number', description: 'First number' },
b: { type: 'number', description: 'Second number' }
},
required: ['a', 'b']
}
}]
};
});
// Handle tools/call
rpc.on('tools/call', async (params) => {
debug(\`Handling tools/call request for tool: \${params.name}\`);
if (params.name === 'add') {
const { a, b } = params.arguments;
return {
content: [{
type: 'text',
text: String(a + b)
}]
};
}
throw new Error('Unknown tool: ' + params.name);
});
// Send initialization notification
rpc.send({
jsonrpc: '2.0',
method: 'initialized'
});
`;
describe('simple-mcp-server', () => {
const rig = new TestRig();
before(async () => {
// Setup test directory with MCP server configuration
await rig.setup('simple-mcp-server', {
settings: {
mcpServers: {
'addition-server': {
command: 'node',
args: ['mcp-server.cjs'],
},
},
},
});
// Create server script in the test directory
const testServerPath = join(rig.testDir!, 'mcp-server.cjs');
writeFileSync(testServerPath, serverScript);
// Make the script executable (though running with 'node' should work anyway)
if (process.platform !== 'win32') {
const { chmodSync } = await import('fs');
chmodSync(testServerPath, 0o755);
}
});
test('should add two numbers', async () => {
// Test directory is already set up in before hook
// Just run the command - MCP server config is in settings.json
const output = await rig.run('add 5 and 10');
const foundToolCall = await rig.waitForToolCall('add');
assert.ok(foundToolCall, 'Expected to find an add tool call');
// Validate model output - will throw if no output, fail if missing expected content
validateModelOutput(output, '15', 'MCP server test');
assert.ok(output.includes('15'), 'Expected output to contain the sum (15)');
});
});
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