It needs following changes as per latest watir-webdriver version and ruby version > 2.5.0 :
require "rubygems"
require "watir"
require 'browserstack-automate'
require 'yaml'
BrowserStack.for "cucumber"
path = "features/support/config.yaml"
local_config = YAML.load_file(path)
USERNAME = local_config['BS_USERNAME']
AUTOMATE_KEY = local_config['BS_AUTHKEY']
browserstack_url = 'https://' + USERNAME + ':' + AUTOMATE_KEY + '@hub-cloud.browserstack.com/wd/hub'
Before do |scenario|
browser = Watir::Browser.new :chrome, {url: browserstack_url}
@browser = browser
@browser.driver.manage.window.maximize
end
After do |scenario|
@browser.close
end