supertest

What is supertest?

The supertest npm package is a high-level abstraction for testing HTTP, allowing you to test your Node.js HTTP servers using a fluent API. It is built on top of the SuperAgent library and provides a simple and flexible way to assert HTTP responses in your tests.

What are supertest's main functionalities?

HTTP Assertions

This feature allows you to make assertions on the HTTP response, such as the status code, content type, and body content. The code sample demonstrates how to test an Express.js route.

const request = require('supertest');
const express = require('express');
const app = express();

app.get('/user', function(req, res) {
  res.status(200).json({ name: 'john' });
});

describe('GET /user', function() {
  it('responds with json', function(done) {
    request(app)
      .get('/user')
      .expect('Content-Type', /json/)
      .expect('Content-Length', '15')
      .expect(200, done);
  });
});

Integration Testing

Supertest can be used for integration testing of an entire application by sending requests to the routes and asserting the expected responses. The code sample shows how to test for both a successful response and a 404 error.

const request = require('supertest');
const app = require('../app');

describe('Integration Testing', function() {
  it('responds to /', function(done) {
    request(app)
      .get('/')
      .expect(200, done);
  });

  it('404 everything else', function(done) {
    request(app)
      .get('/foo/bar')
      .expect(404, done);
  });
});

Asynchronous/Await Support

Supertest works with async/await syntax, allowing for cleaner and more readable asynchronous test code. The code sample demonstrates an asynchronous test using async/await.

const request = require('supertest');
const app = require('../app');

describe('Async/Await Support', function() {
  it('responds to /', async () => {
    await request(app)
      .get('/')
      .expect(200);
  });
});

Other packages similar to supertest

axios

Axios is a promise-based HTTP client for the browser and Node.js. While it is not specifically designed for testing like supertest, it can be used in combination with testing frameworks to make HTTP requests and assert responses.

nock

Nock is an HTTP server mocking and expectations library for Node.js. Unlike supertest, which performs integration tests against an actual server, nock allows you to test modules that perform HTTP requests by mocking the responses, without having to have an actual server running.

chai-http

Chai-http is a plugin for the Chai assertion library that enables HTTP assertions. Similar to supertest, it allows for testing HTTP servers, but it is designed to be used with the Chai assertion library, providing a different syntax and additional assertion capabilities.

README

SuperTest

HTTP assertions made easy via superagent.

About

The motivation with this module is to provide a high-level abstraction for testing HTTP, while still allowing you to drop down to the lower-level API provided by superagent.

Getting Started

Install SuperTest as an npm module and save it to your package.json file as a development dependency:

npm install supertest --save-dev

Once installed it can now be referenced by simply calling require('supertest');

Example

You may pass an http.Server, or a Function to request() - if the server is not already listening for connections then it is bound to an ephemeral port for you so there is no need to keep track of ports.

SuperTest works with any test framework, here is an example without using any test framework at all:

const request = require('supertest');
const express = require('express');

const app = express();

app.get('/user', function(req, res) {
  res.status(200).json({ name: 'john' });
});

request(app)
  .get('/user')
  .expect('Content-Type', /json/)
  .expect('Content-Length', '15')
  .expect(200)
  .end(function(err, res) {
    if (err) throw err;
  });

Here's an example with mocha, note how you can pass done straight to any of the .expect() calls:

describe('GET /user', function() {
  it('respond with json', function(done) {
    request(app)
      .get('/user')
      .set('Accept', 'application/json')
      .expect('Content-Type', /json/)
      .expect(200, done);
  });
});

One thing to note with the above statement is that superagent now sends any HTTP error (anything other than a 2XX response code) to the callback as the first argument if you do not add a status code expect (i.e. .expect(302)).

If you are using the .end() method .expect() assertions that fail will not throw - they will return the assertion as an error to the .end() callback. In order to fail the test case, you will need to rethrow or pass err to done(), as follows:

describe('POST /users', function() {
  it('responds with json', function(done) {
    request(app)
      .post('/users')
      .send({name: 'john'})
      .set('Accept', 'application/json')
      .expect(200)
      .end(function(err, res) {
        if (err) return done(err);
        done();
      });
  });
});

You can also use promises

describe('GET /users', function() {
  it('responds with json', function() {
    return request(app)
      .get('/users')
      .set('Accept', 'application/json')
      .expect(200)
      .then(response => {
          assert(response.body.email, '[e-mail]')
      })
  });
});

Expectations are run in the order of definition. This characteristic can be used to modify the response body or headers before executing an assertion.

describe('POST /user', function() {
  it('user.name should be an case-insensitive match for "john"', function(done) {
    request(app)
      .post('/user')
      .send('name=john') // x-www-form-urlencoded upload
      .set('Accept', 'application/json')
      .expect(function(res) {
        res.body.id = 'some fixed id';
        res.body.name = res.body.name.toUpperCase();
      })
      .expect(200, {
        id: 'some fixed id',
        name: 'john'
      }, done);
  });
});

Anything you can do with superagent, you can do with supertest - for example multipart file uploads!

request(app)
.post('/')
.field('name', 'my awesome avatar')
.attach('avatar', 'test/fixtures/avatar.jpg')
...

Passing the app or url each time is not necessary, if you're testing the same host you may simply re-assign the request variable with the initialization app or url, a new Test is created per request.VERB() call.

request = request('http://localhost:5555');

request.get('/').expect(200, function(err){
  console.log(err);
});

request.get('/').expect('heya', function(err){
  console.log(err);
});

Here's an example with mocha that shows how to persist a request and its cookies:

const request = require('supertest');
const should = require('should');
const express = require('express');
const cookieParser = require('cookie-parser');

describe('request.agent(app)', function() {
  const app = express();
  app.use(cookieParser());

  app.get('/', function(req, res) {
    res.cookie('cookie', 'hey');
    res.send();
  });

  app.get('/return', function(req, res) {
    if (req.cookies.cookie) res.send(req.cookies.cookie);
    else res.send(':(')
  });

  const agent = request.agent(app);

  it('should save cookies', function(done) {
    agent
    .get('/')
    .expect('set-cookie', 'cookie=hey; Path=/', done);
  });

  it('should send cookies', function(done) {
    agent
    .get('/return')
    .expect('hey', done);
  });
})

There is another example that is introduced by the file agency.js

API

You may use any superagent methods, including .write(), .pipe() etc and perform assertions in the .end() callback for lower-level needs.

.expect(status[, fn])

Assert response status code.

.expect(status, body[, fn])

Assert response status code and body.

.expect(body[, fn])

Assert response body text with a string, regular expression, or parsed body object.

.expect(field, value[, fn])

Assert header field value with a string or regular expression.

.expect(function(res) {})

Pass a custom assertion function. It'll be given the response object to check. If the check fails, throw an error.

request(app)
  .get('/')
  .expect(hasPreviousAndNextKeys)
  .end(done);

function hasPreviousAndNextKeys(res) {
  if (!('next' in res.body)) throw new Error("missing next key");
  if (!('prev' in res.body)) throw new Error("missing prev key");
}

.end(fn)

Perform the request and invoke fn(err, res).

Notes

Inspired by api-easy minus vows coupling.

License

MIT