src/Service/validateService.php
public function date($date)
    {
        $this->errorMessage = null;
        require_once 'Zend/Validate/Date.php';
        $validator = new \Zend_Validate_Date();
        $result = $validator->isValid($date);
        if (!$result) {
            $this->errorMessage = MessageHelper::getMessage("VALIDATESVC_DATE_INVALID", array($this->fieldNameMask));
        }
        return $result;
    }
public function date($date)
    {
        $this->errorMessage = null;
        require_once 'Zend/Validate/Date.php';
        $validator = new \Zend_Validate_Date();
        $result = $validator->isValid($date);
        if (!$result) {
            $this->errorMessage = MessageHelper::getMessage("VALIDATESVC_DATE_INVALID", array($this->fieldNameMask));
        }
        return $result;
    }
Built-in \Zend date check using YYYY-MM-DD

@param string in date format $date
@return boolean Valid?