function test_follow_invalid_username()
    {
        $usr = new mdl_users();
        $usr->update_avatar(1, APP_ROOT . 'media/default_avatar.jpg');

        $_SERVER['HTTP_HOST'] = 'localhost';

        // catch result with output buffering
        ob_start();

        $msg = new ctrl_messages();
        $msg->params = array('messages', 'follow', 'invalid_+++');
        $msg->follow();

        $result = ob_get_contents();
        ob_end_clean();

        $this->assertEquals($result, 'Invalid username');
    }
    function test_update_avatar_invalid_avatar()
    {
        $this->setExpectedException('invalid_avatar_exception');

        $avatar = APP_ROOT . 'tests/models/fls/no_such_file.jpg';

        $users = new mdl_users();
        $users->update_avatar(1, $avatar);
    }