Talk about falling at the first hurdle. My test script:

<?php

require_once('PHPUnit/Framework.php');

class TransferResponseTest extends PHPUnit_TestCase {

    ...

}

Running my test case:

$ phpunit TransferResponseTest

Fatal error: Class 'PHPUnit_TestCase' not found in 
/Volumes/Data/greg/code/syndicate/tests/TransferResponseTest.php on line 5
$ php -i | grep include_path
include_path => .:/usr/lib/php => .:/usr/lib/php
$ ls -l /usr/lib/php/PHPUnit/
total 8
drwxr-xr-x  16 root  wheel   544 27 Mar 19:03 Extensions
drwxr-xr-x  28 root  wheel   952 27 Mar 19:03 Framework
-rw-r--r--   1 root  wheel  3193 27 Mar 19:03 Framework.php
drwxr-xr-x   8 root  wheel   272 27 Mar 19:03 Runner
drwxr-xr-x   5 root  wheel   170 27 Mar 19:03 TextUI
drwxr-xr-x  32 root  wheel  1088 27 Mar 19:03 Util

I copied /etc/php.ini-default to /etc/php.ini and explicitly specified the include path as /usr/lib/php/ with an end / but still no success.

$ php -i | grep include_path
include_path => .:/usr/lib/php/ => .:/usr/lib/php/
$ phpunit TransferResponseTest.php 
PHP Fatal error:  Class 'PHPUnit_TestCase' not found in 
/Volumes/Data/greg/code/syndicate/tests/TransferResponseTest.php on line 5
$ phpunit --version
PHPUnit 3.4.11 by Sebastian Bergmann.

Any ideas?