API Testing with Nock

This repository is used to try out API testing using nock, mocha, chai and chai-http.

The test server will be set up using express.

Setting Up

• Just run npm install if you're cloning this repository along with the package.json file
• The instructions below are for starting from scratch

Initialize the repository

• Install nodejs and npm
  sudo apt install nodejs

• If npm wasn't installed along with nodejs, install it manually
  sudo apt install npm

• Create package.json file
  npm init

• Create .gitignore file
  touch .gitignore

• Install express
  npm install express

Install testing dependencies

• Install nock, mocha, chai and chai-http
npm install --save-dev nock mocha chai chai-http

• Modify test script in package.json

"scripts": {
    "test": "mocha"
  },

Mocking HTTP requests using nock

• For each describe block, create a nock interceptor for the http route that is being tested in the before hook

describe('GET /route/to/be/tested', () => {
    before(() => {
      nock(host)
      .get('/route/to/be/tested')
      .reply(200, 'This is some fake data sent by the nock interceptor.')
    })

    it('should get do something', (done) => {
      // test something
      // call done() to signal callback end (only when using `chai-http`)
    })
  })

• Run npm test to execute the tests without a live server (duh, that's the whole point)

Recording fixtures using Nock Back

• Nocks can become cumbersome to write, especially when they return different results with each call

• Fortunately, nock supports fixture recording and playback

• Set up the fixture directory and mode to use

const nockBack = require('nock').back

nockBack.fixtures = __dirname + '/fixtures'
nockBack.setMode('record')

• For each http request to record/test, pass in the desired file name for the recorded fixture, call the http request before finally using the recorded fixture to run the tests

• Take note to call nockDone() after recording the fixture and after completion of the tests

• You can use other packages such as http or request to make the http request as well

• Ensure that you pass in the same fixture file name for both nockBack() calls

// Pass in desired file name for recorded fixture
nockBack('myFixture.json', async (nockDone) => {
  // Record the fixture
  await axios.get('https://some-random-website.com')
  nockDone()

  // Use the recorded fixture for tests
  nockBack('myFixture.json', (nockDone) => {
    describe('GET /route/to/be/tested', () => {
        // test something
        // call done() to signal callback end (only when using `chai-http`)
      })
    })
    nockDone()
  })
})

Recording fixtures using Nock Recorder

• to be done soon