node-mocks-http

What is node-mocks-http?

The node-mocks-http package is a tool for creating mock HTTP objects for testing purposes in Node.js applications. It allows developers to simulate HTTP requests and responses, making it easier to test Express.js middleware and route handlers without needing a real HTTP server.

What are node-mocks-http's main functionalities?

Mocking HTTP Requests

This feature allows you to create a mock HTTP request object. You can specify the method, URL, and parameters to simulate different types of requests.

const httpMocks = require('node-mocks-http');

const request = httpMocks.createRequest({
  method: 'GET',
  url: '/user/42',
  params: {
    id: '42'
  }
});

console.log(request.method); // 'GET'
console.log(request.url); // '/user/42'
console.log(request.params.id); // '42'

Mocking HTTP Responses

This feature allows you to create a mock HTTP response object. You can set the status code and send data, and then inspect the response to verify its properties.

const httpMocks = require('node-mocks-http');

const response = httpMocks.createResponse();

response.status(200).send('OK');

console.log(response._getStatusCode()); // 200
console.log(response._getData()); // 'OK'

Mocking HTTP Headers

This feature allows you to create a mock HTTP request with specific headers. You can then inspect the headers to ensure they are set correctly.

const httpMocks = require('node-mocks-http');

const request = httpMocks.createRequest({
  headers: {
    'content-type': 'application/json'
  }
});

console.log(request.headers['content-type']); // 'application/json'

Mocking HTTP Cookies

This feature allows you to create a mock HTTP request with cookies. You can then inspect the cookies to ensure they are set correctly.

const httpMocks = require('node-mocks-http');

const request = httpMocks.createRequest({
  cookies: {
    token: '12345'
  }
});

console.log(request.cookies.token); // '12345'

Other packages similar to node-mocks-http

supertest

Supertest is a popular library for testing HTTP endpoints. It provides a high-level abstraction for testing HTTP, making it easy to send requests and assert responses. Unlike node-mocks-http, Supertest actually sends HTTP requests to a server, which can be useful for end-to-end testing.

nock

Nock is a library for HTTP mocking and expectations. It allows you to intercept HTTP requests and provide predefined responses. Nock is more focused on mocking external HTTP requests, whereas node-mocks-http is more focused on creating mock request and response objects for internal testing.

sinon

Sinon is a versatile library for creating spies, stubs, and mocks. While it is not specifically designed for HTTP mocking, it can be used in conjunction with other libraries to mock HTTP requests and responses. Sinon provides more general-purpose mocking capabilities compared to node-mocks-http.

README

Mock 'http' objects for testing Express, Next.js and Koa routing functions, but could be used for testing any Node.js web server applications that have code that requires mockups of the request and response objects.

Installation

This project is available as a NPM package.

$ npm install node-mocks-http --save-dev
$ npm install @types/node @types/express --save-dev # when using TypeScript

or

$ yarn add node-mocks-http --dev
$ yarn add @types/node @types/express --dev # when using TypeScript

After installing the package include the following in your test files:

const httpMocks = require('node-mocks-http');

Usage

Suppose you have the following Express route:

app.get('/user/:id', routeHandler);

And you have created a function to handle that route's call:

const routeHandler = function( request, response ) { ... };

You can easily test the routeHandler function with some code like this using the testing framework of your choice:

exports['routeHandler - Simple testing'] = function (test) {
    const request = httpMocks.createRequest({
        method: 'GET',
        url: '/user/42',
        params: {
            id: 42
        }
    });

    const response = httpMocks.createResponse();

    routeHandler(request, response);

    const data = response._getJSONData(); // short-hand for JSON.parse( response._getData() );
    test.equal('Bob Dog', data.name);
    test.equal(42, data.age);
    test.equal('[e-mail]', data.email);

    test.equal(200, response.statusCode);
    test.ok(response._isEndCalled());
    test.ok(response._isJSON());
    test.ok(response._isUTF8());

    test.done();
};

TypeScript typings

The typings for TypeScript are bundled with this project. In particular, the .createRequest(), .createResponse() and .createMocks() methods are typed and are generic. Unless specified explicitly, they will be return an Express-based request/response object:

it('should handle expressjs requests', () => {
    const mockExpressRequest = httpMocks.createRequest({
        method: 'GET',
        url: '/user/42',
        params: {
            id: 42
        }
    });
    const mockExpressResponse = httpMocks.createResponse();

    routeHandler(request, response);

    const data = response._getJSONData();
    test.equal('Bob Dog', data.name);
    test.equal(42, data.age);
    test.equal('[e-mail]', data.email);

    test.equal(200, response.statusCode);
    test.ok(response._isEndCalled());
    test.ok(response._isJSON());
    test.ok(response._isUTF8());

    test.done();
});

The expected type parameter in the mock request and response expects any type that extends the NodeJS http.IncomingRequest interface or Fetch API Request class. This means you can also mock requests coming from other frameworks too. An example for NextJS request will look like this:

it('should handle nextjs requests', () => {
    const mockExpressRequest = httpMocks.createRequest<NextApiRequest>({
        method: 'GET',
        url: '/user/42',
        params: {
            id: 42
        }
    });
    const mockExpressResponse = httpMocks.createResponse<NextApiResponse>();

    // ... the rest of the test as above.
});

It is also possible to mock requests from the NextJS new AppRouter:

it('should handle nextjs app reouter requests', () => {
    const mockExpressRequest = httpMocks.createRequest<NextRequest>({
        method: 'GET',
        url: '/user/42',
        params: {
            id: 42
        }
    });
    const mockExpressResponse = httpMocks.createResponse<NextResponse>();

    // ... the rest of the test as above.
});

API

.createRequest()

httpMocks.createRequest(options)

Where options is an object hash with any of the following values:

option	description	default value
method	request HTTP method	'GET'
url	request URL	''
originalUrl	request original URL	url
baseUrl	request base URL	url
path	request path	''
params	object hash with params	{}
session	object hash with session values	undefined
cookies	object hash with request cookies	{}
socket	object hash with request socket	{}
signedCookies	object hash with signed cookies	undefined
headers	object hash with request headers	{}
body	object hash with body	{}
query	object hash with query values	{}
files	object hash with values	{}

The object returned from this function also supports the Express request functions (.accepts(), .is(), .get(), .range(), etc.). Please send a PR for any missing functions.

.createResponse()

httpMocks.createResponse(options);

Where options is an object hash with any of the following values:

option	description	default value
locals	object that contains response local variables	{}
eventEmitter	event emitter used by response object	mockEventEmitter
writableStream	writable stream used by response object	mockWritableStream
req	Request object being responded to	null

NOTE: The out-of-the-box mock event emitter included with node-mocks-http is not a functional event emitter and as such does not actually emit events. If you wish to test your event handlers you will need to bring your own event emitter.

Here's an example:

const httpMocks = require('node-mocks-http');
const res = httpMocks.createResponse({
  eventEmitter: require('events').EventEmitter
});

// ...
  it('should do something', function(done) {
    res.on('end', function() {
      assert.equal(...);
      done();
    });
  });
// ...

This is an example to send request body and trigger it's 'data' and 'end' events:

const httpMocks = require('node-mocks-http');
const req = httpMocks.createRequest();
const res = httpMocks.createResponse({
    eventEmitter: require('events').EventEmitter
});

// ...
it('should do something', function (done) {
    res.on('end', function () {
        expect(response._getData()).to.equal('data sent in request');
        done();
    });

    route(req, res);

    req.send('data sent in request');
});

function route(req, res) {
    let data = [];
    req.on('data', (chunk) => {
        data.push(chunk);
    });
    req.on('end', () => {
        data = Buffer.concat(data);
        res.write(data);
        res.end();
    });
}
// ...

.createMocks()

httpMocks.createMocks(reqOptions, resOptions);

Merges createRequest and createResponse. Passes given options object to each constructor. Returns an object with properties req and res.

Design Decisions

We wanted some simple mocks without a large framework.

We also wanted the mocks to act like the original framework being mocked, but allow for setting of values before calling and inspecting of values after calling.

For Developers

We are looking for more volunteers to bring value to this project, including the creation of more objects from the HTTP module.

This project doesn't address all features that must be mocked, but it is a good start. Feel free to send pull requests, and a member of the team will be timely in merging them.

If you wish to contribute please read our Contributing Guidelines.

Release Notes

Most releases fix bugs with our mocks or add features similar to the actual Request and Response objects offered by Node.js and extended by Express.

See the Release History for details.

License

Licensed under MIT.

Changelog

v 1.17.1

• Fix direct access to the headers [Issue #319][319].