FileUtils#compare_file

# File tmp/rubies/ruby-3.3.0/lib/fileutils.rb, line 1507
def compare_file(a, b)
  return false unless File.size(a) == File.size(b)
  File.open(a, 'rb') {|fa|
    File.open(b, 'rb') {|fb|
      return compare_stream(fa, fb)
    }
  }
end