String url = "http://test.com";
        String result = helper.convert(url);

        assertNotNull(result);
        assertNotNull(helper.duplicateHostList);
    }

    public void test_convert_emptyList() {
        DuplicateHostHelper helper = new DuplicateHostHelper();
        helper.duplicateHostList = new ArrayList<>();

        String url = "http://test.com";
        String result = helper.convert(url);