mongo-mock

library4.2.0jsnpmunverified

Mongo-Mock (v4.2.0, last released 2022) is an in-memory mock implementation of the MongoDB server, designed to mimic the official MongoDB Node.js driver API. It allows developers to test MongoDB interactions without a real database, supporting basic CRUD operations, async simulation with configurable delay, optional disk persistence, and some query operators. Compared to alternatives like mongodb-memory-server, it is lighter-weight but has limited feature coverage and is no longer actively maintained.

testing

npm install mongo-mock

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MONGO-MOCK

mongo-mock

testingjavascriptv4.2.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

MongoClient

✓ import { MongoClient } from 'mongo-mock'

✗ const MongoClient = require('mongodb').MongoClient

mongo-mock exports a top-level MongoClient, not from 'mongodb' package. Use ES import or require('mongo-mock') directly.

default import

✓ import mongodb from 'mongo-mock'

✗ import * as mongodb from 'mongo-mock'

Default import gives an object with MongoClient, etc. Namespace import is not needed.

require CommonJS

✓ const mongodb = require('mongo-mock')

✗ const { MongoClient } = require('mongo-mock')

Destructuring from require works, but the entire object is also fine. The package supports both CJS and ESM.

Connect to an in-memory mock, insert documents, and query them using async callbacks.

import { MongoClient } from 'mongo-mock'; // optional: set to 0 for synchronous behavior (default delay is 400ms) MongoClient.max_delay = 0; // optional: persist data to disk MongoClient.persist = 'mongo.json'; const url = 'mongodb://localhost:27017/myproject'; MongoClient.connect(url, {}, (err, client) => { if (err) { console.error(err); return; } const db = client.db(); const collection = db.collection('documents'); collection.insertMany([{ a: 1 }, { a: 2 }, { a: 3 }], (err, result) => { console.log('inserted', result); collection.findOne({ a: 2 }, (err, doc) => { console.log('found', doc); db.close(); }); }); });

Debug

Known issues

gotchaDefault async delay of 400ms can cause slow tests if not set to 0.

fix

Set MongoClient.max_delay = 0 for synchronous behavior.

affects: >=1.0.0

gotchaNot all MongoDB features are implemented; advanced queries (aggregation, geospatial) may fail silently.

fix

Check the GitHub issues or README for supported features. Use a different mock for complex pipelines.

affects: >=1.0.0

breakingIn v4, the API changed from callback-only to support promises, but callbacks are still default.

fix

Ensure you handle both callbacks and promises correctly. If using promises, omit the callback parameter.

affects: >=4.0.0 <5.0.0

deprecatedThe package is no longer actively maintained; last release 2022.

fix

Consider migrating to mongodb-memory-server for active support.

affects: >=4.0.0

Errors

Common errors & fixes

MongoClient is not a constructor

Using import/require incorrectly, e.g., importing default as class.

fix

Use: const { MongoClient } = require('mongo-mock');

Cannot find module 'mongo-mock'

Package not installed or misspelled.

fix

Run: npm install mongo-mock

TypeError: db.collection is not a function

Using the old driver API where db is the client; in mongo-mock v4, client.db() returns a database object.

fix

Call client.db() to get the db object before using collection.

Timeout - Async callback was not invoked

Test framework expecting callback but mongo-mock's default delay (400ms) may exceed timeout.

fix

Set MongoClient.max_delay = 0 or increase test timeout.

Upgrade

Version history

4.2.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

9 hits · last 30 days

node

Resources

githubhttps://github.com/williamkapke/mongo-mock ↗

packagemongo-mock ↗

homepagehttps://github.com/williamkapke/mongo-mock ↗