Phrozn\Outputter\PlainOutputter::stderr PHP Method

    public function stderr($msg, $status = self::STATUS_FAIL)
    {
        if (defined('STDERR')) {
            fwrite(STDERR, $msg);
        } else {
            echo $msg;
            if (count(\ob_get_status()) !== 0) {
                ob_flush();
            }
        }
        return $this;
    }

 public function testStdErrWithResource()
 {
     $fp = fopen('/tmp/stderr', 'w+');
     define('STDERR', $fp);
     fclose($fp);
     $outputter = new Outputter();
     $outputter->stderr('sending output', '');
     $this->assertSame('sending output', trim(file_get_contents('/tmp/stderr')));
 }