When\When::byday PHP Method

    public function byday($bywdaylist, $delimiter = ",")
    {
        if (is_string($bywdaylist) && strpos($bywdaylist, $delimiter) !== false) {
            // remove any accidental delimiters
            $bywdaylist = trim($bywdaylist, $delimiter);
            $bywdaylist = explode($delimiter, $bywdaylist);
        } else {
            if (is_string($bywdaylist)) {
                // remove any accidental delimiters
                $bywdaylist = trim($bywdaylist, $delimiter);
                $bywdaylist = array($bywdaylist);
            }
        }
        if (is_array($bywdaylist) && Valid::daysList($bywdaylist)) {
            $this->bydays = self::createDaysList($bywdaylist);
            return $this;
        }
        throw new \InvalidArgumentException("bydays: Accepts (optional) positive and negative values between 1 and 53 followed by a valid week day");
    }

 /**
  * @expectedException InvalidArgumentException
  */
 public function testInvalidbyDay()
 {
     $test = new When();
     $test->byday(array("+5MO", "-20MO", "31TU", "-92SA"));
 }