Automated Testing!

• Kode that tests other code
   
• Automatically run (on build?)
   
• Can be run on file changes
  • Like webpack, but for QA


• Verifies that the program works as intended

Three types (+++)

• Unit
  • ​Single module in complete isolation
     
• Integration
  • Between dependencies
  • Actually start the server
     
• End-to-end
  • Start the server
  • Auto-click buttons
  • No manual testing

Mocha

• Framework & test runner
• describe & it

describe('GET /messages', () => {
 it('should require a token', (done) => {
  // do something
 });
});

import { greet } from '../Greeting.js';

describe('Greeting', () => {
 it('should greet on the form "Hello, <name>!', () => {
  const result = greet('Liam');
  const expected = 'Hello, Liam!';

  // now what?
 });
});

Simple JS module

API endpoint

Chai

• Sexy assertion library
   
• Used with Mocha

import { expect } from 'chai'; // !

import { greet } from '../Greeting.js';

describe('Greeting', () => {
 it('should greet on the form "Hello, <name>!', () => {
  const result = greet('Liam');
  const expected = 'Hello, Liam!';

  // this is what
  expect(result).to.equal('Hello, ' + name + '!');
 });
});

Some details

• Run tests with $ mocha
   
• Mocha looks for tests in ./test/*.js
  • ./test/**/*.js with --recursive
     
• mocha.opts file for settings

Installation

• $ npm install --save-dev mocha
• $ npm install --save-dev chai

ES2015 support

• $ npm install --save-dev babel-register
   
• $ mocha --compilers js:babel-register
   
• .babelrc file (ditch the query thing pls)

Custom reporters

$ mocha --reporter <reporter>

(the important things)

Server-side testing

• Let's just test the API endpoints
  • Not really unit tests

describe('GET /messages', () => {
 it('should return a JSON array', () => {

  // Make the API available

  // Send a request

  // Verify the response

  // Notify Mocha you are done

 });
});

Server-side testing

import express from 'express';
import api from '../api.js';

const app = express();

describe('GET /messages', () => {
 it('should return a JSON array', () => {

  // Make the API available
  app.use(api);

  // Send a request

  // Verify the response

  // Notify Mocha you are done

 });
});

Server-side testing

import express from 'express';
import request from 'supertest';

import api from '../api.js';

const app = express();

describe('GET /messages', () => {
 it('should return a JSON array', () => {

  // Make the API available
  app.use(api);

  // Send a request
  request(app)
   .get('/messages')

  // Verify the response

  // Notify Mocha you are done

 });
});

• supertest
   
• Based on superagent
  • Popular HTTP lib
  • Before fetch
     
• $ npm i -D supertest

Server-side testing

import express from 'express';
import request from 'supertest';

import api from '../api.js';

const app = express();

describe('GET /messages', () => {
 it('should return a JSON array', () => {

  // Make the API available
  app.use(api);

  // Send a request
  request(app)
   .get('/messages')

  // Verify the response
   .expect(200)
   .expect('Content-Type', /json/)

  // Notify Mocha you are done

 });
});

• supertest
   
• Based on superagent
  • Popular HTTP lib
  • Before fetch
     
• $ npm i -D supertest

Server-side testing

import express from 'express';
import request from 'supertest';

import api from '../api.js';

const app = express();

describe('GET /messages', () => {
 it('should return a JSON array', done => {

  // Make the API available
  app.use(api);

  // Send a request
  request(app)
   .get('/messages')

  // Verify the response
   .expect(200)
   .expect('Content-Type', /json/)

  // Notify Mocha you are done
   .end(done);

 });
});

• supertest
   
• Based on superagent
  • Popular HTTP lib
  • Before fetch
     
• $ npm i -D supertest

Server-side testing

import express from 'express';
import request from 'supertest';
import { expect } from 'chai';

import api from '../api.js';

const app = express();

describe('GET /messages', () => {
 it('should return a JSON array', done => {

  // Make the API available
  app.use(api);

  // Send a request
  request(app)
   .get('/messages')

  // Verify the response
   .expect(200)
   .expect('Content-Type', /json/)
   .expect(res => {
     expect(res.body).to.be.instanceOf(Array);
   })

  // Notify Mocha you are done
   .end(done);

 });
});

• supertest
   
• Based on superagent
  • Popular HTTP lib
  • Before fetch
     
• $ npm i -D supertest

front-end: Jest?

npm install --save-dev babel-jest \
                       babel-preset-jest \
                       jest-cli

• Looks for __tests__/*.js
• Designed to test modules (export/import, aka single files)
• mocks all modules automatically

jest.mock('XHR'); // note: by default, this is done automatically in Jest
doWork();
const MockXHR = require('XHR');
// assert that MockXHR got called with the right arguments

let oldXHR = XHR;
XHR = function MockXHR() {};
doWork();
// assert that MockXHR got called with the right arguments
XHR = oldXHR; // if you forget this bad things will happen

Meh, just use Mocha

import React from 'react';
import TestUtils from 'react-addons-test-utils';
import EmailInput from '../../../src/web/components/EmailInput.jsx';

describe('EmailInput', () => {
  it('is a div that contains a label', () => {
    // ...
  });
});

• Pure functions are easy to test
   
• Redux => everything is a prop
   
• Components are functions of props
   
• Small components are easiest

Shallow rendering

• react-addons-test-utils
   
• Render a component one level deep

import React from 'react';
import TestUtils from 'react-addons-test-utils';

import { expect } from 'chai';

describe('EmailInput', () => {
 it('should be a div', () => {
  const renderer = TestUtils.createRenderer();

  renderer.render(
    <EmailInput label={label}
      placeholder={placeholder}
      onChange={onChange}/>
  );

  const component = renderer.getRenderOutput();

  // Verify that a div is displayed
  expect(component.type).to.equal('div');
 });
});

import { expect }  from 'chai';
import React from 'react';
import TestUtils from 'react-addons-test-utils';
import EmailInput from '../../../src/web/components/EmailInput.jsx';

describe('EmailInput', () => {
  it('contains expected tags & label', () => {
    const label = 'Email goes here';
    const placeholder = 'someone@example.xyz';
    const onChange = email => {};

    const renderer = TestUtils.createRenderer();

    renderer.render(
      <EmailInput label={label}
        placeholder={placeholder}
        onChange={onChange}/>
    );

    const component = renderer.getRenderOutput();

    // Verify that a div is displayed
    expect(component.type).to.equal('div');

    // ... that contains only a label
    const labelElement = component.props.children;
    expect(labelElement.type).to.equal('label');
    expect(labelElement.props.children[0]).to.equal(label);
    
    const inputElement = labelElement.props.children[1];
    expect(inputElement.type).to.equal('input');
  });
});