url = "gcs://bucket_with_underscores/file";
        exp = "bucket_with_underscores";
        assertEquals(exp, transformer.getHostOnFile(url));

    }

    @Test
    public void test_getHost_unexpected() {
        String url, exp;
        final FessFileTransformer transformer = createInstance();

        url = null;
        exp = "";
        assertEquals(exp, transformer.getHostOnFile(url));