Disable CSS Animations in Poltergeist & Phantomjs. Phantomjs does not like to wait for animations, and you can run in to nasty test flickers because of it. This pattern will disable animations in test env, and not touch any app code.

gistfile1.md

# env.rb or spec_helper.rb

Capybara.register_driver :poltergeist do |app|
  opts = {
    extensions: ["#{Rails.root}/features/support/phantomjs/disable_animations.js"] # or wherever
  }

  Capybara::Poltergeist::Driver.new(app, opts)
end

Capybara.javascript_driver = :poltergeist

// disable_animations.js
var disableAnimationStyles = '-webkit-transition: none !important;' +
                             '-moz-transition: none !important;' +
                             '-ms-transition: none !important;' +
                             '-o-transition: none !important;' +
                             'transition: none !important;'

window.onload = function() {
  var animationStyles = document.createElement('style');
  animationStyles.type = 'text/css';
  animationStyles.innerHTML = '* {' + disableAnimationStyles + '}';
  document.head.appendChild(animationStyles);
};

As a followup, I found that triggering earlier in the loading cycle worked consistently:

document.addEventListener('DOMContentLoaded', function() {
  // code here as in the gist
}

Hi guys, you might like this approach, by using middleware:
https://gist.github.com/rilian/c259360c3ffa9562b29ec552c6b2b6c6

Helped me a lot

CJBridge's solution worked for us and seemed preferable over the middleware solution.