Add unit test to dubbo-monitor module
import com.alibaba.dubbo.rpc.ProxyFactory;
import com.alibaba.dubbo.rpc.Result;
import com.alibaba.dubbo.rpc.RpcException;
import junit.framework.Assert;
import org.junit.Test;
import java.util.Arrays;
import java.util.List;
/**
 * DubboMonitorTest
 */
public class DubboMonitorTest {
    private final Invoker<MonitorService> monitorInvoker = new Invoker<MonitorService>() {
        @Override
        public Class<MonitorService> getInterface() {
            return MonitorService.class;
        }
        public URL getUrl() {
            return URL.valueOf("dubbo://127.0.0.1:7070?interval=20");
        }
        @Override
        public boolean isAvailable() {
            return false;
        }
        public Result invoke(Invocation invocation) throws RpcException {
            return null;
        }
        @Override
        public void destroy() {
        }
    };