AMA: JS vs Ruby

Butch Mayhew asks…

I have noticed you blogging more about JS frameworks. How do these compare to Watir/Ruby? Would you recommend one over the other?

My response…

I had a discussion recently with Chuck van der Linden about this same topic as he has a lot of experience with Watir and is now looking at JavaScript testing frameworks like I have done.

Some Background built an entirely new UI for managing sites using 100% JavaScript with React for the main UI components. I am responsible for e2e automated tests across this UI, and whilst I originally contemplated, and trialled even, using Ruby, this didn’t make long term sense for where the original WordPress developers are mostly PHP and the newer UI developers are all JavaScript.

Whilst I see merit in both views: I still think having your automated acceptance tests in the same language as your application leads to better maintainability and adoptability.

I still think writing automated acceptance tests in Ruby is much cleaner and nicer than JavaScript Node tests, particularly as Ruby allows meta-programming which means page objects can be implemented really neatly.

The JavaScript/NodeJS landscape is still very immature where people are using various tools/frameworks/compilers and certain patterns or de facto standards haven’t really emerged yet. The whole ES6/ES2015/ES2016 thing is very confusing to newcomers like me, especially on NodeJS where some ES6+ features are supported, but others require something like Babel to compile your code.

But generally with the direction ES is going, writing page objects as classes is much nicer than using functions for everything as in ES5.

Whilst there’s nothing I have found that is better (or even as good) in JavaScript/Mocha/WebDriverJS than Ruby/RSpec/Watir-WebDriver, I still think it’s a better long term decision for to use the JavaScript NodeJS stack for our e2e tests.

Watir-WebDriver with GhostDriver on OSX: headless browser testing

GhostDriver has been released which means it is now easy to run reliable headless WebDriver tests on Mac OSX.

Steps to get working on OSX

  1. First make sure you have homebrew installed
  2. Run
    brew update


    brew install phantomjs

    which should install PhantomJS 1.8.1 or newer

  3. Run irb and start using GhostDriver!
    require 'watir-webdriver'
    b = :phantomjs
    b.goto ""
    b.url #""
    b.title #"Google"

I’ve tested it on a large test suite (123 scenarios) and it behaves the same as other browsers with full JavaScript support. It took 8m13s in total: surprisingly it is slightly slower than ChromeDriver (7m30s) in my testing, but a little faster than the Firefox Driver (9m33s).

Well done to all involved in this project. It’s great to see a reliable, realistic headless browser with full JavaScript support for WebDriver finally released.

And yes, in case you’re wondering, it does screenshots!

Getting the WebDriver driver from a WebDriver element

In watir-webdriver it is really easy to access both the webdriver driver and the watir browser objects from an element:

require 'watir-webdriver'
b =
b.goto ''
button = b.button(name: 'btnK')
button.driver #webdriver
button.browser #watir browser

I never knew how to do this in C# until someone named Robert left a comment yesterday on an old blog post with instructions on how to do so.

You can get the webdriver by using.
var driver = ((IWrapsDriver)webElement).WrappedDriver;

Neat. This means the C# check image present extension method I wrote about previously can be implemented directly from the element itself:

public static bool IsImageVisible(this IWebElement image)
  var driver = ((IWrapsDriver)image).WrappedDriver;
  var script = TestConfig.DriverType == "ie"
             ? "return arguments[0].complete"
             : "return (typeof arguments[0].naturalWidth!=\"undefined\"" +
             " && arguments[0].naturalWidth>0)";
  return (bool)((IJavaScriptExecutor)driver).ExecuteScript(script, image);

This means it can be simply called like:


instead of the cumbersome:


Thanks Robert!

Checking an image is actually visible using WebDriver

I didn’t realize it’s actually a little tricky to check that an image is loaded when using WebDriver. WebDriver will only complain if the image tag you’re looking for isn’t in the DOM, not if the image link is broken and not actually visible.

For example, in watir-webdriver (ruby), this doesn’t really work as I would expect as the image isn’t actually visible on the ‘brokenimage’ page.

require 'watir-webdriver'
b = :firefox
b.goto ''
puts b.image(id: 'watermelon').visible? #true but is not visible

The way to check that is is actually visible is to check a JavaScript property ‘naturalWidth’ is greater than 0.

b = :firefox
b.goto ''
puts b.execute_script("return (typeof arguments[0].naturalWidth!=\"undefined\" && arguments[0].naturalWidth>0)", b.image(id: 'watermelon'))

Unfortunately this doesn’t work in IE, so you should use the ‘complete’ JavaScript method in IE (which doesn’t work in other browsers):

b = :firefox
b.goto ''
puts b.execute_script("return arguments[0].complete", b.image(id: 'watermelon'))

In C#, you can wrap this up into a WebDriver extension method so you can this directly from Driver passing in the image element.

public static bool IsImageVisible(this IWebDriver driver, IWebElement image)
    var script = TestConfig.DriverType == "ie"
                ? "return arguments[0].complete"
                : "return (typeof arguments[0].naturalWidth!=\"undefined\"" +
                  " && arguments[0].naturalWidth > 0)";
    return (bool) ((IJavaScriptExecutor) driver).ExecuteScript(script, image);

// Usage

If it’s important that images load correctly in your application, you should probably start putting some of these in your WebDriver page objects. It’s simple to write a verify images method on a page that iterates through each image in the DOM and checks that it’s visible using the techniques above. Have fun.

Update: 30 November
I wrote about a slightly more elegant C# approach to do this directly from the element.

The webdriver-user-agent gem now supports random user agents

My webdriver-user-agent gem now supports random user agents. This idea belonged to Christoph Pilka who released the webdriver-user-agent-randomizer gem and suggested that we merge this feature back into the orginal gem.

Well, I have done it and now you can access this functionality like so:

require 'selenium-webdriver'
require 'webdriver-user-agent'
driver = UserAgent.driver(:agent => :random)
driver.execute_script('return navigator.userAgent')
# random agent like "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.2) Gecko/20010726 Netscape6/6.1"

See README for full details.