Method test

/**
 * Method to test for a valid color in hexadecimal.
 *
 * @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   1.7.0
 */
public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
{
    $value = trim($value);
    // If the field is empty and not required, the field is valid.
    $required = (string) $element['required'] === 'true' || (string) $element['required'] === 'required';
    if (!$required && empty($value)) {
        return true;
    }
    if ($value[0] != '#') {
        return false;
    }
    // Remove the leading # if present to validate the numeric part
    $value = ltrim($value, '#');
    // The value must be 6 or 3 characters long
    if (!((\strlen($value) == 6 || \strlen($value) == 3) && ctype_xdigit($value))) {
        return false;
    }
    return true;
}