Testing JavaScript, now with more Chrome

Starting today, I am using Chrome to run automated browser tests. I tell Chrome to browse through my sites, click buttons, and (mis)behave like a regular human. And Chrome does so, without complaints, after every little change I make.

A normal part of creating a website is testing it. See if all the buttons work, see if nothing goes unexpectedly bad, see if everything looks okay. Testing by hand is soul-crushingly boring though. So there are scripts to help us do that.

For years I have used a mini-browser called PhantomJS. This was okay; it is based on Webkit (Safari) and things usually work as they should. But not always. PhantomJS is not a real browser, so it can do a bit less. Also, browsers change so fast these days, it’s impossible to keep up if you’re not part of a big team. So PhantomJS began showing it’s age.

Today I made the switch to Headless Chrome. This is the copy of Chrome I have on my computer, but without a visible screen. The advantage: tests run with a main stream browser that’s in the hands of millions. No more unexplained timeouts or excuses that tests cannot do some obvious thing.

Chrome as Pac-Man, eating computer chips

Here is how I did it, for Cucumber on a Rails project.

  1. Remove poltergeist from Gemfile
  2. Add selenium-webdriver and chromedriver-helper to it (in group test)
  3. Run bundle install
  4. Remove features/support/poltergeist.rb
  5. Add Headless Chrome configuration in features/support/chromedriver.rb:
require 'chromedriver/helper'

Capybara.register_driver :headless_chrome do |app|
  capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
    chromeOptions: { args: %w(headless disable-gpu) }
  )

  Capybara::Selenium::Driver.new app,
    browser: :chrome,
    desired_capabilities: capabilities
end

Capybara.javascript_driver = :headless_chrome

That’s it! Tests were still green, and feel a little faster too.

You want proof?

Look at the Pull Request that made this change.