public function addSuite($description, callable $fn, $pending = null, $focused = false)
    {
        $suite = $this->createSuite($description, $fn, $pending, $focused);

        $this->getCurrentSuite()->addTest($suite);
        array_unshift($this->suites, $suite);
        $suite->define();
        array_shift($this->suites);

        return $suite;
    }