public function testDeleteGroupFromFileSystem()
 {
     \DBG::log('*** testDeleteGroupFromFileSystem ***');
     $this->addValuesFileSystem();
     Setting::init('MultiSiteTest', 'testgroup7', 'FileSystem');
     Setting::delete(null, 'testgroup7');
     Setting::flush();
     $this->assertNull(Setting::getValue('key7.1'));
     $this->assertNull(Setting::getValue('key7.2'));
     $this->deleteValuesFileSystem();
 }