In-memory MongoDB for test?

Question

I am writing some integration and system tests for my NodeJS application using a MongoDB database. The test framework I use is Mocha and Supertest. Is it possible to setup MongoDB as an in-memory database which I can use to only test which then wipes away all my collections and documents when the test is done?

Answer 1

You can accomplish this using mongodb-memory-server. The package downloads a mongod binary to your home directory and instantiates a new memory-backed MondoDB instance as needed. For each test file you can spin up a new server which means you can run them all parallel.

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For readers using jest and the native mongodb driver, you may find this class useful:

const { MongoClient } = require('mongodb'); const { MongoMemoryServer } = require('mongodb-memory-server');  // Extend the default timeout so MongoDB binaries can download jest.setTimeout(60000);  // List your collection names here const COLLECTIONS = [];  class DBManager {   constructor() {     this.db = null;     this.server = new MongoMemoryServer();     this.connection = null;   }    async start() {     const url = await this.server.getUri();     this.connection = await MongoClient.connect(url, { useNewUrlParser: true });     this.db = this.connection.db(await this.server.getDbName());   }    stop() {     this.connection.close();     return this.server.stop();   }    cleanup() {     return Promise.all(COLLECTIONS.map(c => this.db.collection(c).remove({})));   } }  module.exports = DBManager; 

Then in each test file you can do the following:

const dbman = new DBManager();  afterAll(() => dbman.stop()); beforeAll(() => dbman.start()); afterEach(() => dbman.cleanup()); 

I suspect this approach may be similar for other testing frameworks.