mock-req-res

1.2.1 verified Sat Apr 25 auth: no javascript

Library for creating mock Express request and response objects for unit testing controllers and middleware. Version 1.2.1 works with Sinon >10.0.0 and Node >=8.10.0. Provides mockRequest and mockResponse functions that return sinon stubs/spies for all standard Express req/res properties. Supports extensibility via options parameter. Lightweight and focused on isolated unit tests, unlike full integration tools like supertest. Includes TypeScript definitions via @types/mock-req-res. Release cadence is slow, with minor updates as needed.

Common errors

error TypeError: mockRequest is not a constructor ↓

cause Attempting to use 'new mockRequest()' instead of calling it as a function.

fix

Remove 'new': const req = mockRequest(options);

error Cannot find module 'sinon' ↓

cause Sinon is a peer dependency and must be installed separately.

fix

Run: npm install sinon --save-dev (ensure compatible version).

error TypeError: mockResponse(...).json is not a function ↓

cause Likely using a very old version (<1.0.0) where .json did not exist; or failing to pass options that include json.

fix

Upgrade to latest version: npm install mock-req-res@latest --save-dev. The default mockResponse includes .json as a spy.

Warnings

breaking Version 1.0.0 changed the API; mockRequest and mockResponse replaced earlier mockReq and mockRes functions. ↓

fix Replace mockReq with mockRequest and mockRes with mockResponse. Update import paths.

deprecated Older versions (≤1.1.6) used sinon <10; peer dep now requires sinon >10.0.0. ↓

fix Upgrade sinon to at least 10.0.0.

gotcha The mockRequest and mockResponse functions are not constructors; do not use 'new'. ↓

fix Call normally: mockRequest() or mockResponse(), not new mockRequest().

gotcha Headers are not populated by default until version 1.1.0; test code may rely on headers being present. ↓

fix Provide headers in options: mockRequest({ headers: { 'content-type': 'application/json' } }).

gotcha TypeScript definitions are provided by @types/mock-req-res, not included in the main package. ↓

fix Install @types/mock-req-res as a devDependency if using TypeScript.

Install

npm install mock-req-res

yarn add mock-req-res

pnpm add mock-req-res

Imports

mockRequest

wrong

const mockRequest = require('mock-req-res').mockRequest

correct

import { mockRequest } from 'mock-req-res'

Named export; can be destructured from CJS require or ESM import.

mockResponse

wrong

const mockResponse = require('mock-req-res')

correct

import { mockResponse } from 'mock-req-res'

Not the default export; must destructure or use .mockResponse.

mockRequest and mockResponse (both)
```
import { mockRequest, mockResponse } from 'mock-req-res'
```
Both are exported as named exports.

Quickstart

Shows basic usage: creating mock req and res, invoking a controller, and asserting on sinon stubs/spies.

const { mockRequest, mockResponse } = require('mock-req-res');
const sinon = require('sinon');

// Sample controller that uses req.body and res.json
const createThing = (req, res) => {
  const { name, description } = req.body;
  if (!name || !description) {
    return res.status(400).json({ error: 'Invalid properties' });
  }
  res.json({ id: 1, name, description });
};

// Test setup
const req = mockRequest({ body: { name: 'test', description: 'desc' } });
const res = mockResponse();

// Invoke controller
createThing(req, res);

// Assertions
console.log(res.json.calledOnce); // true
console.log(res.json.firstCall.args[0]); // { id: 1, name: 'test', description: 'desc' }
console.log(res.status.called); // false (no error)