How to overwrite sfConfig setting in functional lime test in symfony 1.4

My Problem is the following i wanted to test some functionality that depended on a certain setting in the sfConfig. Proposed the setting is app_foo and its default is false.

The "standard" way to test is like:

$browser = new sfTestFunctional(new sfBrowser());

$browser->
  get('/path_to/index')->
  ...
  end();

BUT it does not work to change the setting like

sfConfig::set('app_foo', true);
$browser = new sfTestFunctional(new sfBrowser());

The sfConfig cannot be overwritten in the test because the sfConfig is reset on the next request.

BUT a field named 'rawConfiguration' in the browser instance is added to the sfConfig for the request. So the solution is to set this array:

$browserEngine = new sfBrowser();
$browser = new sfTestFunctional($browserEngine);
// overwrite an sfConfig parameter in the browser context
$browserEngine->rawConfiguration = array_merge($browserEngine->rawConfiguration, array('app_foo' => true));

Then the action knows the sfConfig::get('app_foo') with the value true.