@Test
    public void test_getClientRuleList() {
        FessCrawlerThread crawlerThread = new FessCrawlerThread();

        List<Pair<String, Pattern>> list = crawlerThread.getClientRuleList(null);
        assertEquals(0, list.size());

        list = crawlerThread.getClientRuleList("");
        assertEquals(0, list.size());

        list = crawlerThread.getClientRuleList(" ");
        assertEquals(0, list.size());

     *
     * @param crawlerThread the thread to wait for; null threads are ignored
     */
    private void joinCrawlerThread(final Thread crawlerThread) {
        if (crawlerThread != null) {
            try {
                crawlerThread.join();
            } catch (final Exception e) {
                logger.info("Interrupted crawling process: name={}", crawlerThread.getName());
            }
        }