Method test

/**
 * Method to test given values for a subform..
 *
 * @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 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   3.9.7
 */
public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
{
    // Get the form field object.
    $field = $form->getField($element['name'], $group);
    if (!$field instanceof SubformField) {
        throw new \UnexpectedValueException(sprintf('%s is no subform field.', $element['name']));
    }
    if ($value === null) {
        return true;
    }
    $subForm = $field->loadSubForm();
    // Multiple values: Validate every row.
    if ($field->multiple) {
        foreach ($value as $row) {
            if ($subForm->validate($row) === false) {
                // Pass the first error that occurred on the subform validation.
                $errors = $subForm->getErrors();
                if (!empty($errors[0])) {
                    return $errors[0];
                }
                return false;
            }
        }
    } else {
        if ($subForm->validate($value) === false) {
            // Pass the first error that occurred on the subform validation.
            $errors = $subForm->getErrors();
            if (!empty($errors[0])) {
                return $errors[0];
            }
            return false;
        }
    }
    return true;
}