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
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__, {
useNewUrlParser: true,
useUnifiedTopology: true,
});
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'],
};See Also
Publish
$ git checkout master
$ yarn version
$ yarn publish
$ git push origin master --tagsLicense
MIT © Shelf