module Minitest::Assertions

def capture_io
  _synchronize do
    begin
  require 'stringio'
  captured_stdout, captured_stderr = StringIO.new, StringIO.new
  orig_stdout, orig_stderr = $stdout, $stderr
  $stdout, $stderr         = captured_stdout, captured_stderr
  yield
  return captured_stdout.string, captured_stderr.string
ensure
  $stdout = orig_stdout
  $stderr = orig_stderr
    end
  end
end