Behat\Behat\Tester\Cli\RerunController::getFileName PHP Method

    private function getFileName()
    {
        if (null === $this->cachePath || null === $this->key) {
            return null;
        }
        if (!is_dir($this->cachePath)) {
            mkdir($this->cachePath, 0777);
        }
        return $this->cachePath . DIRECTORY_SEPARATOR . $this->key . '.rerun';
    }