Phantom JS VS Selenium- Which is a superior testing framework?

Guest Post

An Article by Amanda

App testing is an indispensable component of the entire app development project. No matter what kind of functionality and feature you’ve incorporated into the app, ignoring to test it for bugs is a big ‘No’. Thanks to the availability of high-end JavaScript testing frameworks like Selenium and PhantomJS, we can conveniently test the web apps in varied headless browsers as well as real browsers. Continue reading the post as I’ll be taking you through the key points of difference between PhantomJS and Selenium- two best-performing JavaScript testing frameworks. So, let’s get to learn the differences right away!

Uncovering the thin line of difference between Real browsers and Headless Browsers

Before moving forward towards exploring the two equally well-known testing frameworks viz: PhantomJS and Selenium, it is vital for you to be familiar with the key difference between headless and real browsers. Well, a headless browser is basically a web browser that lacks a graphical user interface. That means, it is a browser which accesses specific web pages but doesn’t show them to an internet user. Such browsers are solely used for providing certain web page content to other software programs. On the other hand, we have the real browsers wherein the app/website testing is already defined as per a specific set of actions that would be taken by a human being in the chosen desktop/mobile browser. It is also important to know that execution of a real browser testcase will expect you to start a real browser, followed by controlling it using automation APIs for performing the specified actions.

And now, let me take you on a journey where I’ll be exploring two major JavaScript testing frameworks viz: PhantomJS and Selenium
Firstly, let’s get to know about PhantomJS


Phantom is an invisible, programmable browser which doesn’t behave like a real browser window. With the flexibility to execute commands much faster, Phantom can easily work in synchronization with a suitable test runner and testing framework. For instance, PhantomJS can work with Mocha, Capybara etc. Suitable for first layer of JavaScript app testing, PhantomJS has its API based on JavaScript. Backed by command-line based usage, PhantomJS doesn’t render anything on the screenand ensures that the website’s JavaScript code is sandboxed, refraining it from interacting with the main tool.
A look at the advantages associated with PhantomJS

Some of the visible pros of PhantomJS include:

  1. Doesn’t need to be integrated with a third-party service
  2. Is capable of executing multiple test cases within a record time period
  3. Serves as a self-contained command-line application
  4. Consumes fewer resources
  5. Useful in case of smoke testing the web apps. That means, you can use PhantomJS for testing app as part of app development workflow or in the un-interrupted integration server

Now, let’s get to know about the disadvantages associated with PhantomJS

  1. Running UI Testing for web applications that need to run on multiple web browsers doesn’t yield maximum test coverage
  2. Doesn’t include an entire ecosystem
  3. PhantomJS serves as a single version of WebKit- not a good option for web app testers

Coming to Selenium Testing framework now

As a great open source automation tool, Selenium supports all major operating systems and browsers like Firefox, Mozilla, IE and Safari. Capable of running multiple tests, Selenium is a JavaScript automated testing framework which supports all popular programming languages like Ruby, Java, Python and C#. Distributed in the form of a single jar file, Selenium Server needs to be downloaded. You can use it as a JavaScript engine, with the need for running Selenium Server each time you intend to run the web app tests.

Next, we’ll look into visible pros associated with using the Selenium Testing framework

  1. Backed by a large community of developers who are continuously working on creation of plugins that are required for ensuring 100% compatibility of Selenium with all latest JavaScript front-end frameworks
  2. Accompanied by extensive documentation that is simple, clear and easy-to-understand
  3. Selenium is capable of using bindings for allowing you to use common programming languages like C#, Ruby, Python and JavaScript
  4. Allows you to execute feature test in real time, over the World Wide Web
  5. Saves you a lot of debugging effort simply because you are able to view see the activities of the browser in real time

Finally, let’s have a look at the disadvantages associated with using the Selenium framework

  1. If you’re interested in testing your web app on different browsers and operating systems, then you’ll need to have centralization for your Selenium setup
  2. The Selenium framework refrains you from running more than few browsers on one machine at a time
  3. Running multiple test cases with Selenium turns to be a time-consuming regime

Wrapping it all up

Neglecting the unit testing for your web apps would land you in a lot of trouble when it comes to maintaining the overall performance of your app. Hence, it is better to choose a JavaScript testing framework that is not only easy-to-use but even works as a fantastic option for implementing tests for the app’s logout functionality.

About the Author: Amanda is currently working for Xicom Technologies Ltd- a renowned Android App Development Services. She has been an avid IT personnal with special interest in writing posts that serve as handy guide for individuals looking out to build a strong career in IT services and solutions sector.

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