@shelf/jest-mongodb

jest-mongodb

Jest preset to run MongoDB memory server

Usage

0. Install

$ yarn add @shelf/jest-mongodb --dev

Make sure mongodb is installed in the project as well, as it's required as a peer dependency.

1. Create jest.config.js

module.exports = {
  preset: '@shelf/jest-mongodb',
};

If you have a custom jest.config.js make sure you remove testEnvironment property, otherwise it will conflict with the preset.

2. Create jest-mongodb-config.js

See mongodb-memory-server

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      version: '4.0.3',
      skipMD5: true,
    },
    autoStart: false,
    instance: {},
  },
};

To use the same database for all tests pass the config like this:

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      version: '4.0.3',
      skipMD5: true,
    },
    instance: {
      dbName: 'jest',
    },
    autoStart: false,
  },
};

To use separate database for each jest worker pass the useSharedDBForAllJestWorkers: false (doesn't create process.env variable when using this option):

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      skipMD5: true,
    },
    autoStart: false,
    instance: {},
  },

  useSharedDBForAllJestWorkers: false,
};

To use dynamic database name you must pass empty object for instance field:

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      version: '4.0.3',
      skipMD5: true,
    },
    instance: {},
    autoStart: false,
  },
};

To use another uri environment variable name you must set mongoURLEnvName field:

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      version: '4.0.3',
      skipMD5: true,
    },
    instance: {},
    autoStart: false,
  },
  mongoURLEnvName: 'MONGODB_URI',
};

To use mongo as a replica set you must add the replSet config object and set count and storageEngine fields:

module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      skipMD5: true,
    },
    autoStart: false,
    instance: {},
    replSet: {
      count: 3,
      storageEngine: 'wiredTiger',
    },
  },
};

3. Configure MongoDB client

Library sets the process.env.MONGO_URL for your convenience, but using of global.__MONGO_URI__ is preferable as it works with useSharedDBForAllJestWorkers: false

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

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

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

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

4. PROFIT! Write tests

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);
});

Cache MongoDB binary in CI by putting this folder to the list of cached paths: ./node_modules/.cache/mongodb-memory-server/mongodb-binaries

You can enable debug logs by setting environment variable DEBUG=jest-mongodb:*

5. Clean collections before each test (optional)

beforeEach(async () => {
  await db.collection('COLLECTION_NAME').deleteMany({});
});

_{See this issue for discussion}

6. Jest watch mode gotcha

This package creates the file globalConfig.json in the project root, when using jest --watch flag, changes to globalConfig.json can cause an infinite loop

In order to avoid this unwanted behaviour, add globalConfig to ignored files in watch mode in the Jest configuation

// jest.config.js
module.exports = {
  watchPathIgnorePatterns: ['globalConfig'],
};

Node 22.12+ and ESM configs

Node 22.12 turned on require() support for ESM by default. If your config is an .mjs file with a default export, @shelf/jest-mongodb now imports it automatically (and still supports CommonJS configs). If you prefer the old behavior, you can run Jest with --no-experimental-require-module.

See Also

• jest-dynamodb

Publish

$ git checkout master
$ yarn version
$ yarn publish
$ git push origin master --tags

License

MIT © Shelf