RackRequestCounter

click.rb

# spec/support/click.rb

module Capybara
  module Node
    class Element < Base

      # Override the default implementation of click so that whenever we click
      # on something, we also wait for any ajax requests to finish.
      def click
        synchronize { base.click }
        wait_for_ajax
      end

    end
  end
end

rack_request_counter.rb

# lib/rack_request_counter.rb
#
# Source, which use jruby and atomic:
# http://blog.salsify.com/engineering/tearing-capybara-ajax-tests
# https://gist.githubusercontent.com/jturkel/9317269/raw/rack_request_blocker.rb

# Rack middleware that keeps track of the number of active requests and can block new requests.
class RackRequestCounter

  @@num_active_requests = 0
  @@nil_requests_at = Time.now

  def self.reset
    @@nil_requests_at = Time.now
    @@num_active_requests = 0
  end

  # Returns the number of requests the server is currently processing.
  def self.num_active_requests
    @@num_active_requests
  end

  def self.nil_requests_at
    @@nil_requests_at
  end

  # 503 status.
  def initialize(app)
    @app = app
  end

  def call(env)
    puts "Hit: #{env["PATH_INFO"]}" if ENV["SHOW_URLS"]
    increment_active_requests
    @app.call(env)
  ensure
    decrement_active_requests
  end

  private

  def increment_active_requests
    @@num_active_requests += 1
  end

  def decrement_active_requests
    @@num_active_requests -= 1

    # Mark this as the last time there were zero requests
    @@nil_requests_at = Time.now if @@num_active_requests == 0
  end

end

wait_for.rb

# spec/support/wait_for.rb
#
# Coupled with a Ruby-side request counter: see /lib/rack_request.counter.rb

class Capybara::Session
  def wait_until(timeout = Capybara.default_wait_time)
    Timeout.timeout(timeout) do
      sleep(0.05) until value = yield
      value
    end
  end
end

# If this is called in a scenario from rspec page will be defined. However,
# we've also overridden Capybara's default 'click' behaviour to also call
# wait_for_ajax; this means we need to load the current session from Capybara.
def wait_for_ajax(timeout = Capybara.default_wait_time)
  page ||= Capybara.current_session

  # After clicking, wait 50ms for an ajax request to fire off
  sleep(0.05)
  page.wait_until(timeout) do
    # If there are no active requests and the last request was over 150ms ago,
    # continue. This means that one AJAX request wasn't depending on another to
    # finish... race condition central.com
    RackRequestCounter.num_active_requests <= 0 && Time.now - RackRequestCounter.nil_requests_at > 0.15
  end
end