Capybara configuration to run a webpack dev server for e2e testing

capybara.rb

# spec/support/capybara.rb
require 'capybara/rails'
require 'capybara/rspec'

# port and url to webpack server
WEB_TEST_PORT = '5005'.freeze
WEB_TEST_URL = "http://localhost:#{WEB_TEST_PORT}".freeze

def capybara_wait_for_webpack_server
  10.times.each do |_|
    begin
      Net::HTTP.get(URI(WEB_TEST_URL))
      return
    rescue Errno::ECONNREFUSED
      sleep 1
    end
  end
end

# https://github.com/thoughtbot/capybara-webkit#configuration
Capybara::Webkit.configure do |config|
  config.raise_javascript_errors = true
end

# https://github.com/teamcapybara/capybara/blob/master/lib/capybara.rb#L35
Capybara.configure do |config|
  # server puntastic will run the webpack server and the rails server
  config.register_server :puntastic do |app, port, host|
    # run webpack server using childprocess gem
    process = ChildProcess.build('yarn', 'start')
    # process.io.inherit! # uncomment for debugging
    process.environment['WEB_PORT'] = WEB_TEST_PORT
    process.environment['API_URL'] = "#{host}:#{port}"
    process.cwd = Rails.root.join('web')
    process.leader = true
    process.detach = true
    begin
      Net::HTTP.get(URI(WEB_TEST_URL))
    rescue
      process.start
      at_exit { process.stop unless process.exited? }
      capybara_wait_for_webpack_server
    end

    # run the Rails API server
    options = { Host: host, Port: port, Threads: "0:4", Silent: true }
    Rack::Handler::Puma.run(app, options)
  end

  # use a javascript driver
  config.default_driver = :webkit
  config.javascript_driver = :webkit

  # use the custom server
  config.server = :puntastic
  config.run_server = true
  config.app_host = WEB_TEST_URL
end