capybara.rb

# place in spec/support/

Capybara.register_driver :poltergeist do |app|
  options = {
    :js_errors    => true,
    :window_size  => [1280, 1440],
    :timeout      => 30
  }
  Capybara::Poltergeist::Driver.new(app, options)
end

database_cleaner_helper.rb

# place in spec/support/features

module DatabaseCleanerHelper
  RSpec.configure do |config|

    config.before(:suite) do
      DatabaseCleaner.clean_with(:truncation)
    end

    config.before(:each) do
      DatabaseCleaner.strategy = :transaction
    end

    config.before(:each, :js => true) do
      DatabaseCleaner.strategy = :truncation
    end

    config.before(:each) do
      DatabaseCleaner.start
    end

    config.after(:each) do
      DatabaseCleaner.clean
      Capybara.reset_sessions!    # Forget the (simulated) browser state
      Capybara.use_default_driver # Revert Capybara.current_driver to Capybara.default_driver
    end

  end
end

example_spec.rb

require 'spec_helper'

describe "JS Example" do
  it "doesn't use javascript driver" do

  end

  it "uses javascript driver", :js => true do

  end
end

Gemfile

group :test do
  gem 'capybara'
  gem 'poltergeist' # gem 'capybara-webkit'
  gem 'database_cleaner'
end

spec_helper.rb

require 'capybara/poltergeist'

Capybara.configure do |config|
  config.javascript_driver = :poltergeist
  config.default_wait_time = 40 # long wait time for to handle jenkins timeouts
end

RSpec.configure do |config|
  config.use_transactional_fixtures = false
  
  config.include DatabaseCleanerHelper, :type => :feature
end