Yii unit testing: phpunit + bootstrap extension + getBasePath

I have a Yii project using the latest bootstrap extension (which might not be important), and while trying to run unit tests, it throwed me an error:

PHP Fatal error:  Uncaught exception 'CException' with message 'CAssetManager.basePath "/usr/bin/assets" is invalid. Please make sure the directory exists and is writable by the Web server process.' in /Users/belerophon/Documents/blah/repos/blah2/libs/yii/yii-1.1.11.58da45/framework/web/CAssetManager.php:134
Stack trace:
#0 /Users/belerophon/Documents/blah/repos/blah2/libs/yii/yii-1.1.11.58da45/framework/web/CAssetManager.php(119): CAssetManager->setBasePath('/usr/bin/assets')
#1 /Users/belerophon/Documents/blah/repos/blah2/libs/yii/yii-1.1.11.58da45/framework/web/CAssetManager.php(240): CAssetManager->getBasePath()
#2 /Users/belerophon/Documents/blah/repos/blah2/libs/bootstrap/yii-bootstrap-1.0.0.alpha5.r280/components/Bootstrap.php(328): CAssetManager->publish('/Users/beleroph...', false, -1, false)
#3 /Users/belerophon/Documents/blah/repos/blah2/libs/bootstrap/yii-bootstrap-1.0.0.alpha5.r280/components/Bootstra in /Users/belerophon/Documents/blah/repos/blah2/libs/yii/yii-1.1.11.58da45/framework/web/CAssetManager.php on line 134

I don't understand why getBasePath is returning "/usr/bin", when running the test code.
Btw, I ran it like this:

cd protected/tests
phpunit unit/UserTest.php

I don't know if this is worth mentioning, but in my directory structure I'm using some symlinks. I have this:

|-- libs
|   |-- bootstrap
|   |   |-- latest -> yii-bootstrap-1.0.0.alpha5.r280
|   |   |-- yii-bootstrap-0.10.1.beta.r254
|   |   `-- yii-bootstrap-1.0.0.alpha5.r280
|   |-- yii
|   |   |-- latest -> yii-1.1.11.58da45
|   |   |-- yii-1.1.10.r3566
|   |   `-- yii-1.1.11.58da45
`-- src
    `-- project.com
        |-- images
        |-- index-test.php
        |-- index.php
        |-- protected
        |   |-- tests
        |   |   |-- WebTestCase.php
        |   |   |-- bootstrap.php
        |   |   |-- fixtures
        |   |   |-- functional
        |   |   |-- phpunit.xml
        |   |   `-- unit
        |   |-- yiic
        |   |-- yiic.bat
        |   `-- yiic.php
        |-- temp.html
        `-- themes
            `-- classic
                `-- views

Notice the symlinks on the lib's folders.

So, for example, my index.php looks like this:

<?php

// change the following paths if necessary
$yii=dirname(__FILE__).'/../../libs/yii/latest/framework/yii.php';
$config=dirname(__FILE__).'/protected/config/main.php';

// remove the following lines when in production mode
defined('YII_DEBUG') or define('YII_DEBUG',true);

// specify how many levels of call stack should be shown in each log message
defined('YII_TRACE_LEVEL') or define('YII_TRACE_LEVEL',3);

require_once($yii);
Yii::createWebApplication($config)->run();

I'm working with the latest Yii release, in a Mac OSX Lion, php 5.3.10
For now, I'm simply unable to run tests with phpunit.

Can someone help me here?

Thanks in advance!
André