// Test ping method
EmptyRequestProto emptyRequest = EmptyRequestProto.newBuilder().build();
client.ping(null, emptyRequest);
// Test echo method
EchoRequestProto echoRequest = EchoRequestProto.newBuilder()
.setMessage("hello").build();
EchoResponseProto echoResponse = client.echo(null, echoRequest);
Assert.assertEquals(echoResponse.getMessage(), "hello");
// Test error method - error should be thrown as RemoteException