Web UI testing in NodeJS

2018/01/15 630 words 3 mins

In this article i would like to demonstrate some tools in NodeJS for testing web UI. They are:

Mocha

Mocha is a Javascript framework for testing. It has a BDD-style syntax (BDD: Behavior-driven development) and allows asychronous call testing. It also supports different assertion libraries and in our exampe we will use chai for assertion.

Chai

Chai is a BDD/TDD assertion library for NodeJS and the browser that can be delightfully paired with any Javascript testing framework.

CasperJS

CasperJS is a helper library for building navigation scenarios. It is often used with PhantomJS but actually it also supports SlimerJS which is another headless browser with the Firefox rendering engine called Gecko.

PhantomJS

PhantomJS is a headless browser with the WebKit rendering engine. It allows running browser-based tests in a headless system.

Check if the Google search is working

Let’s get started with a simple example. Assume we would like to test the following:

Is the Google search page accessible?
Is the search function able to return a list of result?

For the first question, we could simple make a HTTP request to the Google URL and see if it returns a HTTP 200 response code and this could be done easily by CasperJS.

The second question is a bit more complicated. It could be broken down into the following steps.

Wait for the search form
Fill in the form and submit
Check if the result set contains the search text

Let’s go through the code.

Initialize a new NodeJS project

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npm init

Install the following node modules

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npm install casperjs chai mocha phantomjs --save-dev
# In addition to the above libraries, we also need the following extensions.
npm install casper-chai mocha-casperjs --save-dev

Setup the tests

Create the test/google-search.js

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describe('Google Search', function() {
  // Before script for each test
  before(function() {
    casper.start('https://www.google.com.hk/');
  });

  // *** Test 1 ***
  // Is the Google search page accessible?
  it('should have return HTTP 200', function() {
    expect(casper.currentHTTPStatus).to.equal(200);
  });

  // *** Test 2 ***
  // Is the search function able to return a list of result?
  it('should be able to search', function() {
    // Wait for the search form
    casper.waitForSelector('form[action="/search"]', function() {
      'form[action="/search"]'.should.be.inDOM;
    });

    // Fill in the form and submit
    casper.then(function() {
      this.fill('form[action="/search"]', { q: 'Boatswain' }, true);
    });

    // Check if the result set contains text "Boatswain"
    casper.waitForSelector('h3.r a', function() {
      'h3.r a'.should.be.inDOM;
      expect('h3.r a').to.contain.text(/Boatswain/);
    });
  });
});

Add a npm script for running the test

Edit the package.json as follow.

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{
  "name": "ui-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha-casperjs test/google-search.js"
  },
  "author": "ykyuen",
  "license": "ISC",
  "devDependencies": {
    "casper-chai": "^0.3.0",
    "casperjs": "^1.1.4",
    "chai": "^4.1.2",
    "mocha": "^4.1.0",
    "mocha-casperjs": "^0.6.0",
    "phantomjs": "^2.1.7"
  }
}

Run the test

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npm test

A brief test report will be shown after the test run has finished.

Let’s try to fail the test

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// Check if the result set contains text "Boatswain"
casper.waitForSelector('h3.r a', function() {
  'h3.r a'.should.be.inDOM;
  expect('h3.r a').to.contain.text(/nosuchtext/);
});

Summary

This example shows how to create a simple web UI test in NodeJS and execute the test in command line prompt. It could be used in smoke testing for staging environment. Please also note that CasperJS is NOT for unit testing but rather web UI testing. In addition, test runner like Karma does not support CasperJS. If you are looking for unit testing solution, you should probably rule out CasperJS.

Complete example is available on gitlab.com.