module ActiveSupport::Testing::Isolation::Subprocess

def run_in_isolation(&blk)
  require "tempfile"
  if ENV["ISOLATION_TEST"]
    yield
    test_result = defined?(Minitest::Result) ? Minitest::Result.from(self) : dup
    File.open(ENV["ISOLATION_OUTPUT"], "w") do |file|
      file.puts [Marshal.dump(test_result)].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.unpack1("m")
    end
  end
end