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

1module.exports = {
2  preset: '@shelf/jest-mongodb',
3};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      version: '4.0.3',
5      skipMD5: true,
6    },
7    autoStart: false,
8    instance: {},
9  },
10};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      version: '4.0.3',
5      skipMD5: true,
6    },
7    instance: {
8      dbName: 'jest',
9    },
10    autoStart: false,
11  },
12};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      skipMD5: true,
5    },
6    autoStart: false,
7    instance: {},
8  },
9
10  useSharedDBForAllJestWorkers: false,
11};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      version: '4.0.3',
5      skipMD5: true,
6    },
7    instance: {},
8    autoStart: false,
9  },
10};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      version: '4.0.3',
5      skipMD5: true,
6    },
7    instance: {},
8    autoStart: false,
9  },
10  mongoURLEnvName: 'MONGODB_URI',
11};

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

1module.exports = {
2  mongodbMemoryServerOptions: {
3    binary: {
4      skipMD5: true,
5    },
6    autoStart: false,
7    instance: {},
8    replSet: {
9      count: 3,
10      storageEngine: 'wiredTiger',
11    },
12  },
13};

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

1const {MongoClient} = require('mongodb');
2
3describe('insert', () => {
4  let connection;
5  let db;
6
7  beforeAll(async () => {
8    connection = await MongoClient.connect(global.__MONGO_URI__, {
9      useNewUrlParser: true,
10      useUnifiedTopology: true,
11    });
12    db = await connection.db();
13  });
14
15  afterAll(async () => {
16    await connection.close();
17  });
18});

4. PROFIT! Write tests

1it('should insert a doc into collection', async () => {
2  const users = db.collection('users');
3
4  const mockUser = {_id: 'some-user-id', name: 'John'};
5  await users.insertOne(mockUser);
6
7  const insertedUser = await users.findOne({_id: 'some-user-id'});
8  expect(insertedUser).toEqual(mockUser);
9});

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)

1beforeEach(async () => {
2  await db.collection('COLLECTION_NAME').deleteMany({});
3});

_{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

1// jest.config.js
2module.exports = {
3  watchPathIgnorePatterns: ['globalConfig'],
4};

See Also

• jest-dynamodb

Publish

1$ git checkout master
2$ yarn version
3$ yarn publish
4$ git push origin master --tags

License

MIT © Shelf