addTest() should be add()

I'm getting errors from the online docs below
http://www.simpletest.org/en/group_test_tutorial.html

Changing the line:
$this->addTest(new TestOfLogging());
to:
$this->add(new TestOfLogging());
seems to have solved the issue.

A test suite

A test case does not function alone for very long. When coding for real we usually want to run as many tests as quickly and as often as we can. This means grouping them together into test suites that could easily include every test in the application.

Firstly we create a test suite called all_tests.php in the tests folder...

<?php
require_once(dirname(__FILE__) . '/simpletest/autorun.php');
require_once('log_test.php');

class AllTests extends TestSuite {
function __construct() {
parent::__construct();
$this->addTest(new TestOfLogging());
}
}
?>

We hardly notice the difference when things work...