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Spinning up mongod in memory for fast tests. If you run tests in parallel this lib helps to spin up dedicated mongodb servers for every test file in MacOS, *nix, Windows or CI environments (in most cases with zero-config).
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README.md

mongodb-memory-server

CircleCI NPM version Downloads stat Commitizen friendly TypeScript compatible

This package spins up an actual/real MongoDB server programmatically from node, for testing or mocking during development. By default it holds the data in memory. A fresh spun up mongod process takes about 7Mb of memory. The server will allow you to connect your favorite ODM or client library to the MongoDB server and run integration tests isolated from each other.

On install, this package downloads the latest MongoDB binaries and saves them to a cache folder.

On starting a new instance of the memory server, if the binary cannot be found, it will be auto-downloaded, thus the first run may take some time. All further runs will be fast, because they will use the downloaded binaries.

This package automatically downloads binaries from https://fastdl.mongodb.org/ according to your operating system. You can see all available versions for Linux (Ubuntu, RHEL, Debian, SUSE, Amazon), OSX, and Windows.

If your network is behind a proxy, make sure that it is configured through the HTTPS_PROXY or HTTP_PROXY environment variable.

Every MongoMemoryServer instance creates and starts a fresh MongoDB server on some free port. You may start up several mongod simultaneously. When you terminate your script or call stop(), the MongoDB server(s) will be automatically shutdown.

Works perfectly with Travis CI without additional services and addons options in .travis.yml.

Installation

This tool provides three packages for different purposes:

  • With auto-download mongod binary on npm install
  • Without auto-download on npm install

Choose any package, because they are the same. They differ only in the default configuration, which you may override (see section Available options).

Requirements

  • NodeJS: 8+
  • Typescript: 3.7+ (if used)

And one of those:

  • having lsb-core installed (or any that provides the lsb_release command)
  • having an /etc/os-release file that is compliant to the OS-Release Spec
  • having an /etc/*-release file that is compliant to the OS-Release Spec (and does not include lsb)
  • manually specify which version & system should be used

Known Incompatibilities

  • ArchLinux & Alpine do not have an offical mongodb build
  • ArchLinux(Docker) does not have an /etc/os-release file by default

mongodb-memory-server

Auto-downloads the latest mongod binary on npm install to: node_modules/.cache/mongodb-binaries.

yarn add mongodb-memory-server --dev
# OR
npm install mongodb-memory-server --save-dev

mongodb-memory-server-global

Auto-downloads the latest mongod binary on npm install to: %HOME%/.cache/mongodb-binaries / ~/.cache/mongodb-binaries.

yarn add mongodb-memory-server-global --dev
# OR
npm install mongodb-memory-server-global --save-dev

mongodb-memory-server-core

Does NOT auto-download mongod on npm install.

yarn add mongodb-memory-server-core --dev
# OR
npm install mongodb-memory-server-core --save-dev

Note: the package does try to download mongod upon server start if it cannot find the binary.

Usage

Simple server start

import { MongoMemoryServer } from 'mongodb-memory-server';

const mongod = new MongoMemoryServer();

const uri = await mongod.getUri();
const port = await mongod.getPort();
const dbPath = await mongod.getDbPath();
const dbName = await mongod.getDbName();

// some code
//   ... where you may use `uri` for as a connection string for mongodb or mongoose

// you may check instance status, after you got `uri` it must be `true`
mongod.getInstanceInfo(); // return Object with instance data

// you may stop mongod manually
await mongod.stop();

// when mongod killed, it's running status should be `false`
mongod.getInstanceInfo();

// even you forget to stop `mongod` when you exit from script
// special childProcess killer will shutdown it for you

Available options for MongoMemoryServer

All options are optional.

const mongod = new MongoMemoryServer({
  instance: {
    port?: number, // by default choose any free port
    ip?: string, // by default '127.0.0.1', for binding to all IP addresses set it to `::,0.0.0.0`,
    dbName?: string, // by default generate random dbName
    dbPath?: string, // by default create in temp directory
    storageEngine?: string, // by default `ephemeralForTest`, available engines: [ 'devnull', 'ephemeralForTest', 'mmapv1', 'wiredTiger' ]
    replSet?: string, // by default no replica set, replica set name
    auth?: boolean, // by default `mongod` is started with '--noauth', start `mongod` with '--auth'
    args?: string[], // by default no additional arguments, any additional command line arguments for `mongod` `mongod` (ex. ['--notablescan'])
  },
  binary: {
    version?: string, // by default 'latest'
    downloadDir?: string, // by default node_modules/.cache/mongodb-memory-server/mongodb-binaries
    platform?: string, // by default os.platform()
    arch?: string, // by default os.arch()
    checkMD5?: boolean, // by default false OR process.env.MONGOMS_MD5_CHECK
    systemBinary?: string, // by default undefined or process.env.MONGOMS_SYSTEM_BINARY
  },
  autoStart?: boolean, // by default true
});

Replica Set start

import { MongoMemoryReplSet } from 'mongodb-memory-server';

const replSet = new MongoMemoryReplSet({
  replSet: { storageEngine: 'wiredTiger' },
});
await replSet.waitUntilRunning();
const uri = await replSet.getUri();
// or you may obtain the connection config parts:
// const port = await replSet.getPort();
// const dbPath = await replSet.getDbPath();
// const dbName = await replSet.getDbName();

// some code, eg. for mongoose
mongoose.set('useFindAndModify', false);
mongoose.set('useCreateIndex', true);
mongoose.connect(uri, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});
// after some useful code don't forget to disconnect
mongoose.disconnect();

// stop replica set manually
replSet.stop();
// or it should be stopped automatically when you exit from script

Available options for MongoMemoryReplSet

All options are optional.

const replSet = new MongoMemoryReplSet({
  autoStart, // same as for MongoMemoryServer
  binary: binaryOpts, // same as for MongoMemoryServer
  instanceOpts: [
    {
      args, // any additional instance specific args
      port, // port number for the instance
      dbPath, // path to database files for this instance
      storageEngine, // same storage engine options
    },
    // each entry will result in a MongoMemoryServer
  ],
  // unless otherwise noted below these values will be in common with all instances spawned.
  replSet: {
    name, // replica set name (default: 'testset')
    auth, //  enable auth support? (default: false)
    args, // any args specified here will be combined with any per instance args from `instanceOpts`
    count, // number of `mongod` processes to start; (default: 1)
    dbName, // default database for db URI strings. (default: uuid.v4())
    ip, // by default '127.0.0.1', for binding to all IP addresses set it to `::,0.0.0.0`
    oplogSize, // size (in MB) for the oplog; (default: 1)
    spawn, // spawn options when creating the child processes
    storageEngine, // default storage engine for instance. (Can be overridden per instance)
    configSettings: {
      // Optional settings for replSetInitiate command. See https://docs.mongodb.com/manual/reference/command/replSetInitiate/
      chainingAllowed: boolean, // When true it allows secondary members to replicate from other secondary members. When false, secondaries can replicate only from the primary.
      heartbeatTimeoutSecs: number, // Number of seconds that the replica set members wait for a successful heartbeat from each other. If a member does not respond in time, other members mark the delinquent member as inaccessible.
      heartbeatIntervalMillis: number, // The frequency in milliseconds of the heartbeats.
      electionTimeoutMillis: number, // The time limit in milliseconds for detecting when a replica set’s primary is unreachable.
      catchUpTimeoutMillis: number, // Time limit for a newly elected primary to sync (catch up) with the other replica set members that may have more recent writes.
    },
  },
});

Options which can be set via ENVIRONMENT variables

MONGOMS_DOWNLOAD_DIR=/path/to/mongodb/binaries
MONGOMS_PLATFORM=linux
MONGOMS_ARCH=x64
MONGOMS_VERSION=3
MONGOMS_DEBUG=1 # also available case-insensitive values: "on" "yes" "true"
MONGOMS_DOWNLOAD_MIRROR=host # your mirror host to download the mongodb binary
MONGOMS_DOWNLOAD_URL=url # full URL to download the mongodb binary
MONGOMS_DISABLE_POSTINSTALL=1 # if you want to skip download binaries on `npm i` command
MONGOMS_SYSTEM_BINARY=/usr/local/bin/mongod # if you want to use an existing binary already on your system.
MONGOMS_MD5_CHECK=1 # if you want to make MD5 check of downloaded binary.
# Passed constructor parameter `binary.checkMD5` has higher priority.

# GetOS specific ones (for linux only)
MONGOMS_USE_LINUX_LSB_RELEASE # Only try "lsb_release -a"
MONGOMS_USE_LINUX_OS_RELEASE # Only try to read "/etc/os-release"
MONGOMS_USE_LINUX_ANYFILE_RELEASE # Only try to read the first file found "/etc/*-release"

Options which can be set via package.json's config section

You can also use package.json's config section to configure installation process. Environment variables have higher priority than contents of package.json.

{
  "config": {
    "mongodbMemoryServer": {
      "downloadDir": "/path/to/mongodb/binaries",
      "platform": "linux",
      "arch": "x64",
      "version": "3",
      "debug": "1",
      "downloadMirror": "url",
      "disablePostinstall": "1",
      "systemBinary": "/usr/local/bin/mongod",
      "md5Check": "1"
    }
  }
}

Simple test with MongoClient

Take a look at this test file.

Provide connection string to mongoose

import mongoose from 'mongoose';
import { MongoMemoryServer } from 'mongodb-memory-server';

const mongoServer = new MongoMemoryServer();

mongoose.Promise = Promise;
mongoServer.getUri().then((mongoUri) => {
  const mongooseOpts = {
    // options for mongoose 4.11.3 and above
    autoReconnect: true,
    reconnectTries: Number.MAX_VALUE,
    reconnectInterval: 1000,
    useMongoClient: true, // remove this line if you use mongoose 5 and above
  };

  mongoose.connect(mongoUri, mongooseOpts);

  mongoose.connection.on('error', (e) => {
    if (e.message.code === 'ETIMEDOUT') {
      console.log(e);
      mongoose.connect(mongoUri, mongooseOpts);
    }
    console.log(e);
  });

  mongoose.connection.once('open', () => {
    console.log(`MongoDB successfully connected to ${mongoUri}`);
  });
});

For additional information I recommend you to read this article Testing a GraphQL Server using Jest with Mongoose

Several mongoose connections simultaneously

import mongoose from 'mongoose';
import { MongoMemoryServer } from 'mongodb-memory-server';

mongoose.Promise = Promise;

const mongoServer1 = new MongoMemoryServer();
const mongoServer2 = new MongoMemoryServer();

// Firstly create connection objects, which you may import in other files and create mongoose models.
// Connection to databases will be estimated later (after model creation).
const connections = {
  conn1: mongoose.createConnection(),
  conn2: mongoose.createConnection(),
  conn3: mongoose.createConnection(),
};

const mongooseOpts = { // options for mongoose 4.11.3 and above
  promiseLibrary: Promise;
  autoReconnect: true,
  reconnectTries: Number.MAX_VALUE,
  reconnectInterval: 1000,
  useMongoClient: true, // remove this line if you use mongoose 5 and above
};

mongoServer1.getUri('server1_db1').then((mongoUri) => {
  connections.conn1.open(mongoUri, mongooseOpts);
  connection.once('open', () => {
    console.log(`MongoDB successfully connected to ${mongoUri}`);
  });
});

mongoServer1.getUri('server1_db2').then((mongoUri) => {
  connections.conn2.open(mongoUri, mongooseOpts);
  connection.once('open', () => {
    console.log(`MongoDB successfully connected to ${mongoUri}`);
  });
});

mongoServer2.getUri('server2_db').then((mongoUri) => {
  connections.conn3.open(mongoUri, mongooseOpts);
  connection.once('open', () => {
    console.log(`MongoDB successfully connected to ${mongoUri}`);
  });
});

export default connections;


// somewhere in other file
import { Schema } from 'mongoose';
import { conn1, conn2, conn3 } from './file_above';

const userSchema = new Schema({
  name: String,
});

const taskSchema = new Schema({
  userId: String,
  task: String,
});

export default {
  User: conn1.model('user', userSchema),
  Task: conn2.model('task', taskSchema),
  UserOnServer2: conn3.model('user', userSchema),
}

Note: When you create mongoose connection manually, you should do:

import mongoose from 'mongoose';

const opts = { useMongoClient: true }; // remove this option if you use mongoose 5 and above
const conn = mongoose.createConnection(); // just create connection instance
const User = conn.model('User', new mongoose.Schema({ name: String })); // define model
conn.open(uri, opts); // open connection to database (NOT `connect` method!)

With default connection:

import mongoose from 'mongoose';

const opts = { useMongoClient: true }; // remove this option if you use mongoose 5 and above
mongoose.connect(uri, opts);
const User = mongoose.model('User', new mongoose.Schema({ name: String })); // define model

Simple Mocha/Chai test example

Start Mocha with --timeout 60000 cause first download of MongoDB binaries may take a time.

import mongoose from 'mongoose';
import { MongoMemoryServer } from 'mongodb-memory-server';

let mongoServer;
const opts = { useMongoClient: true }; // remove this option if you use mongoose 5 and above

before(async () => {
  mongoServer = new MongoMemoryServer();
  const mongoUri = await mongoServer.getUri();
  await mongoose.connect(mongoUri, opts);
});

after(async () => {
  await mongoose.disconnect();
  await mongoServer.stop();
});

describe('...', () => {
  it('...', async () => {
    const User = mongoose.model('User', new mongoose.Schema({ name: String }));
    const cnt = await User.count();
    expect(cnt).to.equal(0);
  });
});

Simple Jest test example

import mongoose from 'mongoose';
import { MongoMemoryServer } from 'mongodb-memory-server';

// May require additional time for downloading MongoDB binaries
jasmine.DEFAULT_TIMEOUT_INTERVAL = 600000;

let mongoServer;
const opts = { useMongoClient: true }; // remove this option if you use mongoose 5 and above

beforeAll(async () => {
  mongoServer = new MongoMemoryServer();
  const mongoUri = await mongoServer.getUri();
  await mongoose.connect(mongoUri, opts, (err) => {
    if (err) console.error(err);
  });
});

afterAll(async () => {
  await mongoose.disconnect();
  await mongoServer.stop();
});

describe('...', () => {
  it('...', async () => {
    const User = mongoose.model('User', new mongoose.Schema({ name: String }));
    const count = await User.count();
    expect(count).toEqual(0);
  });
});

Additional examples of Jest tests:

AVA test runner

For AVA written detailed tutorial how to test mongoose models by @zellwk.

Docker Alpine

There isn't currently an official MongoDB release for alpine linux. This means that we can't pull binaries for Alpine (or any other platform that isn't officially supported by MongoDB), but you can use a Docker image that already has mongod built in and then set the MONGOMS_SYSTEM_BINARY variable to point at that binary. This should allow you to use mongodb-memory-server on any system on which you can install mongod.

Enable Debug Mode

The Debug mode can be enabled with an Environment-Variable or in the package.json "config" section:

MONGOMS_DEBUG=1 # also available case-insensitive values: "on" "yes" "true"

or

{
  "config": {
    "mongodbMemoryServer": {
      "debug": "1", // also available case-insensitive values: "on" "yes" "true"
    }
  }
}

Travis

It is very important to limit spawned number of Jest workers for avoiding race condition. Cause Jest spawn huge amount of workers for every node environment on same machine. More details Use --maxWorkers 4 or --runInBand option.

script:

-  yarn run coverage
+  yarn run coverage -- --maxWorkers 4

Credits

Inspired by alternative runners for mongodb-prebuilt:

License

MIT

Maintainers

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