url = "s3://bucket-with-dashes/file";
        exp = "bucket-with-dashes";
        assertEquals(exp, transformer.getHostOnFile(url));

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

    }

    @Test
    public void test_getHost_unexpected() {
        String url, exp;

        assertTrue(protocolHelper.isValidFileProtocol("gcs://bucket-with-dashes/path"));
        assertTrue(protocolHelper.isValidFileProtocol("gcs://bucket_with_underscores/path"));
        assertTrue(protocolHelper.isValidFileProtocol("gcs://bucket/path/to/deep/nested/file.txt"));
        assertTrue(protocolHelper.isValidFileProtocol("gcs://bucket/path/ファイル.txt"));