# File activesupport/lib/active_support/testing/isolation.rb, line 65
def run_in_isolation(&blk)
  require "tempfile"

  if ENV["ISOLATION_TEST"]
    yield
    File.open(ENV["ISOLATION_OUTPUT"], "w") do |file|
      file.puts [Marshal.dump(dup)].pack("m")
    end
    exit!
  else
    Tempfile.open("isolation") do |tmpfile|
      env = {
        "ISOLATION_TEST" => self.class.name,
        "ISOLATION_OUTPUT" => tmpfile.path
      }

      test_opts = "-n#{self.class.name}##{name}"

      load_path_args = []
      $-I.each do |p|
        load_path_args << "-I"
        load_path_args << File.expand_path(p)
      end

      child = IO.popen([env, Gem.ruby, *load_path_args, $0, *ORIG_ARGV, test_opts])

      begin
        Process.wait(child.pid)
      rescue Errno::ECHILD # The child process may exit before we wait
        nil
      end

      return tmpfile.read.unpack("m")[0]
    end
  end
end