Error when running with mongodb node driver 7.6 in Jest

Versions

• NodeJS: 22.x
• mongodb-memory-server-*: 11.2.0
• mongodb(the binary version): 8.2.0
• mongodb(the js package): 7.6.0
• system: Ubuntu 24.04

package: mongo-memory-server

What is the Problem?

If installing mongodb-memory-server with mongodb node driver 7.6.0, running in Jest fails with the following error:

    MongoServerSelectionError: Missing required sub-document 'driver' in the client metadata document

       6 |   it('connects successfully to a replica set started by mongodb-memory-server', async () => {
       7 |     console.log('Creating replica set...');
    >  8 |     replSet = await MongoMemoryReplSet.create({ replSet: { count: 1 } });
         |               ^
       9 |     console.log('Replica set created, connecting mongoose...');
      10 |     const uri = replSet.getUri();
      11 |

      at Topology.selectServer (node_modules/mongodb/src/sdam/topology.ts:638:30)
      at Topology._connect (node_modules/mongodb/src/sdam/topology.ts:466:22)
      at Topology.connect (node_modules/mongodb/src/sdam/topology.ts:402:7)
      at topologyConnect (node_modules/mongodb/src/mongo_client.ts:684:9)
      at MongoClient._connect (node_modules/mongodb/src/mongo_client.ts:696:7)
      at MongoClient.connect (node_modules/mongodb/src/mongo_client.ts:608:7)
      at Function.connect (node_modules/mongodb/src/mongo_client.ts:887:12)
      at MongoMemoryReplSet._initReplSet (node_modules/mongodb-memory-server-core/src/MongoMemoryReplSet.ts:669:30)
      at MongoMemoryReplSet.start (node_modules/mongodb-memory-server-core/src/MongoMemoryReplSet.ts:406:5)
      at Function.create (node_modules/mongodb-memory-server-core/src/MongoMemoryReplSet.ts:207:5)
      at Object.<anonymous> (repro.spec.ts:8:15)

More details here: https://github.com/Automattic/mongoose/issues/16499 and this repo: https://github.com/andreglock/mongodb-7.6-hanshake-bug

Code Example

import { MongoMemoryReplSet } from 'mongodb-memory-server';

describe('mongoose 9.9.4 + mongodb handshake regression', () => {
  let replSet: MongoMemoryReplSet;

  it('connects successfully to a replica set started by mongodb-memory-server', async () => {
    console.log('Creating replica set...');
    replSet = await MongoMemoryReplSet.create({ replSet: { count: 1 } });
    console.log('Replica set created, connecting mongoose...');
    const uri = replSet.getUri();

    console.log('Got uri', uri);
  }, 120_000); // increased timeout to rule out slow binary download/replset init

  afterAll(async () => {
    if (replSet) {
      await replSet.stop();
    }
  });
});

Jest config:

/** @type {import('jest').Config} */
module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  testTimeout: 30000,
};

package.json:

{
  "name": "mongoose-mongodb-repro",
  "version": "1.0.0",
  "private": true,
  "type": "commonjs",
  "scripts": {
    "test": "jest"
  },
  "devDependencies": {
    "jest": "^29.7.0",
    "ts-jest": "^29.2.5",
    "typescript": "^5.6.3",
    "@types/jest": "^29.5.14",
    "mongodb-memory-server": "^11.2.0"
  },
  "dependencies": {
    "mongoose": "9.9.4"
  }
}

Debug Output

Put The Debugout output here

Do you know why it happenes?

There's some more info here: https://github.com/Automattic/mongoose/issues/16499

Start by running the supplied Jest reproduction in repro.spec.ts with the listed Node.js, mongodb-memory-server, MongoDB, and driver versions. Read MongoMemoryReplSet.ts around _initReplSet and compare the handshake reports linked in the issue. Done means replica-set creation succeeds with mongodb driver 7.6 and the regression is covered by a test.