web test not working

gistfile1.txt

//class SPSDrupalVariableControllerUnitTest extends DrupalUnitTestCase {
class SPSDrupalVariableControllerUnitTest extends DrupalWebTestCase {
  static function getInfo() {
    return array(
      'name' => 'SPS DrupalVariableController Unit Tests',
      'description' => 'Test the public interface to the DrupalVariableController object',
      'group' => 'SPS',
    );
  }
  /**
   * override setUp
   *
   * we need the Variable module
   */
  public function setUp() {
    parent::setUp('sps', 'xautoload');
    //parent::setUp(array('variable', 'xautoload', 'sps', 'sps_test'));

  }

  public function testTestStorageController() {
    print_r(array(module_exists("xautoload"), module_exists('variable')));