background_firefox.rb

module MakeFirefoxLaunchInBackground
  module_function
  def run
    webdriver_path = `bundle show selenium-webdriver`.chomp
    launcher_path = "#{webdriver_path}/lib/selenium/webdriver/firefox/launcher.rb"
    if !File.exist?(launcher_path)
      raise "Couldn't find the Firefox launcher file at [#{launcher_path}]."
    end

    expected_launch_line = '@binary.start_with @profile, @profile_dir, "-foreground"'
    new_launch_line = '@binary.start_with @profile, @profile_dir#, "-foreground"'

    launcher_content = File.read(launcher_path)
    if !launcher_content.match(expected_launch_line)
      raise "Didn't see the expected launcher code [#{expected_launch_line}]"
    end

    new_launcher_content = launcher_content.gsub(expected_launch_line, new_launch_line)
    File.open(launcher_path, 'w') do |f|
      f.print new_launcher_content
    end
    puts 'done hacking selenium-webdriver Firefox launcher file'
  end
end

MakeFirefoxLaunchInBackground.run

Why the module boilerplate? Why not make the body of run be the entire script?