Ensures that chromedriver always matches the version of Chrome that's currently installed

chromedriver.rb

# https://github.com/flavorjones/chromedriver-helper/issues/79
# http://chromedriver.storage.googleapis.com/index.html

require 'open-uri'
require 'shellwords'

executable = if RUBY_PLATFORM =~ /darwin/
  '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome'
else
  'google-chrome'
end

version = if system("which #{Shellwords.escape(executable)} > /dev/null 2>&1")
  `#{Shellwords.escape(executable)} --version`
else
  fail 'unable to determine Chrome binary location. Chrome must already be installed before installing chromedriver'
end

# Matches all except the last set of digits, as documented here:
# https://sites.google.com/a/chromium.org/chromedriver/downloads/version-selection
if /Google Chrome ([0-9,.]+)\.\d+ \n/ =~ version
  version = Regexp.last_match(1)
else
  fail "unexpected version string: #{version}"
end

chromedriver_version = open("https://chromedriver.storage.googleapis.com/LATEST_RELEASE_#{version}").read

Chromedriver.set_version chromedriver_version