When you get a request for a module controller, like with Request::forge('api/some/controller'), the Framework switches it's request context to the api module, so it knows it has to look in that module for resources like views, config, lang files, etc.
When you run tests, the test classes are instantiated like normal classes, completely outside the Fuel framework. So none of these features will work.
So you could possibly work around it by giving your test classes setup and teardown methods, and add the path manually, something like
public static function setUpBeforeClass() { // number of dirs' up depend on the location of this class in the test tree // the result of the realpath() call should be the module root directory \Finder::instance()->flash(realpath(__DIR__.DS.'..'.DS.'..'.DS.'..'.DS.'..').DS); }
public static function tearDownAfterClass() { \Finder::instance()->clear_flash(); }
// disclaimer: from the top of my head, not tested! ;-)