public File savePublic(String filename) throws IOException
    {
        return publicConfig().save(filename);
    }
@Test
    public void testSavePublicFile() throws IOException
    {
        ZCert cert = new ZCert();
        cert.savePublic(CERT_LOCATION + "/test.cert");
        File file = new File(CERT_LOCATION + "/test.cert");
        assertThat(file.exists(), is(true));
    }