Rack Middleware to disable Disable CSS3/jQuery Animations for Capybara

no_animations.rb

# Copyright (C) [2014] by Keith Tom <keith dot tom at gmail>
# Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE

module Rack
  # disable CSS3 and jQuery animations in test mode for speed, consistency and avoiding timing issues.
  # Usage for Rails:
  # in config/environments/test.rb
  # config.middleware.use Rack::NoAnimations
  class NoAnimations
    def initialize(app, options = {})
      @app = app
    end

    def call(env)
      @status, @headers, @body = @app.call(env)
      return [@status, @headers, @body] unless html?
      response = Rack::Response.new([], @status, @headers)

      @body.each { |fragment| response.write inject(fragment) }
      @body.close if @body.respond_to?(:close)

      response.finish
    end

    private

    def html?
      @headers["Content-Type"] =~ /html/
    end

    def inject(fragment)
      disable_animations = <<-EOF
<script type="text/javascript">(typeof jQuery !== 'undefined') && (jQuery.fx.off = true);</script>
<style>
  * {
     -o-transition: none !important;
     -moz-transition: none !important;
     -ms-transition: none !important;
     -webkit-transition: none !important;
     transition: none !important;
     -o-transform: none !important;
     -moz-transform: none !important;
     -ms-transform: none !important;
     -webkit-transform: none !important;
     transform: none !important;
     -webkit-animation: none !important;
     -moz-animation: none !important;
     -o-animation: none !important;
     -ms-animation: none !important;
     animation: none !important;
  }
</style>
      EOF
      fragment.gsub(%r{</head>}, disable_animations + "</head>")
    end
  end
end

cool, it worked