With the Global Setup/Teardown and Async Test Environment APIs, Jest can work smoothly with MongoDB.

Use jest-mongodb Preset

Jest MongoDB provides all required configuration to run your tests using MongoDB.

1. First install @shelf/jest-mongodb

yarn add @shelf/jest-mongodb --dev

2. Specify preset in your Jest configuration:

{
  "preset": "@shelf/jest-mongodb"
}

3. Write your test

const {MongoClient} = require('mongodb');

describe('insert', () => {
  let connection;
  let db;

  beforeAll(async () => {
    connection = await MongoClient.connect(global.__MONGO_URI__, {
      useNewUrlParser: true,
    });
    db = await connection.db(global.__MONGO_DB_NAME__);
  });

  afterAll(async () => {
    await connection.close();
    await db.close();
  });

  it('should insert a doc into collection', async () => {
    const users = db.collection('users');

    const mockUser = {_id: 'some-user-id', name: 'John'};
    await users.insertOne(mockUser);

    const insertedUser = await users.findOne({_id: 'some-user-id'});
    expect(insertedUser).toEqual(mockUser);
  });
});

There's no need to load any dependencies.

See documentation for details (configuring MongoDB version, etc).