### Question:
RedisProtocol extends AbstractProtocol { @Override public <T> Exporter<T> export(final Invoker<T> invoker) throws RpcException { throw new UnsupportedOperationException("Unsupported export redis service. url: " + invoker.getUrl()); }  @Override int getDefaultPort(); @Override Exporter<T> export(final Invoker<T> invoker); @Override Invoker<T> refer(final Class<T> type, final URL url); static final int DEFAULT_PORT; }### Answer:
@Test public void testExport() { Assertions.assertThrows(UnsupportedOperationException.class, () -> protocol.export(protocol.refer(IDemoService.class, registryUrl))); }