import { INestApplication, Injectable } from '@nestjs/common';
import { Test } from '@nestjs/testing';
import request from 'supertest';
import { McpModule } from '../src/mcp/mcp.module';
import { createStreamableClient } from './utils';
import { Tool } from '../src/mcp/decorators/tool.decorator';
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
@Injectable()
class Tools {
@Tool({
name: 'tool',
description: 'Tool from Module',
})
toolA() {
return 'Tool result';
}
}
const composeMutators = (...mutators: Array<(server: McpServer) => McpServer>) => {
return (server: McpServer) => {
return mutators.reduce((srv, mutator) => mutator(srv), server);
}
}
let fakeTelemetry = jest.fn();
const telemetryMutator = (server: McpServer) => {
const originalConnect = server.connect;
server.connect = async (transport) => {
fakeTelemetry();
return originalConnect.call(server, transport);
}
return server;
}
describe('MCP with mutated telemetry server', () => {
let app: INestApplication;
let port: number;
// Set timeout for all tests in this describe block to 15000ms
jest.setTimeout(15000);
beforeEach(async () => {
fakeTelemetry.mockClear();
})
beforeAll(async () => {
const moduleRef = await Test.createTestingModule({
imports: [
McpModule.forRoot({
name: 'mutated-mcp-server',
version: '0.0.1',
serverMutator: telemetryMutator,
}),
],
providers: [Tools],
exports: [Tools],
}).compile();
app = moduleRef.createNestApplication();
await app.listen(0);
const server = app.getHttpServer();
port = (server.address() as import('net').AddressInfo).port;
});
afterAll(async () => {
await app.close();
});
it('should connect to mutated server', async () => {
const client = await createStreamableClient(port, {
endpoint: `/mcp`,
});
try {
const tools = await client.listTools();
expect(tools.tools.length).toBe(1);
expect(fakeTelemetry).toHaveBeenCalled();
} finally {
await client.close();
}
});
});
