Method test

/**
 * Method to test the calendar value for a valid parts.
 *
 * @param   \SimpleXMLElement  $element  The SimpleXMLElement object representing the `<field>` tag for the form field object.
 * @param   mixed              $value    The form field value to validate.
 * @param   string             $group    The field name group control value. This acts as an array container for the field.
 *                                       For example if the field has name="foo" and the group value is set to "bar" then the
 *                                       full field name would end up being "bar[foo]".
 * @param   Registry           $input    An optional Registry object with the entire data set to validate against the entire form.
 * @param   Form               $form     The form object for which the field is being tested.
 *
 * @return  boolean  True if the value is valid, false otherwise.
 *
 * @since   3.7.0
 */
public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
{
    // If the field is empty and not required, the field is valid.
    $required = (string) $element['required'] === 'true' || (string) $element['required'] === 'required';
    if (!$required && empty($value)) {
        return true;
    }
    if (strtolower($value) === 'now') {
        return true;
    }
    try {
        return Factory::getDate($value) instanceof Date;
    } catch (\Exception $e) {
        return false;
    }
}