diff --git a/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryFactoryTest.java b/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryFactoryTest.java
new file mode 100644
index 0000000000..bae8ac7b38
--- /dev/null
+++ b/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryFactoryTest.java
@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.registry.zookeeper;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.registry.client.ServiceDiscovery;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ZookeeperServiceDiscoveryFactoryTest {
+
+    @Test
+    public void testCreateZookeeperServiceDiscovery() {
+        final URL url = URL.valueOf("test://test:80");
+        final ZookeeperServiceDiscoveryFactory factory = new ZookeeperServiceDiscoveryFactory();
+        ServiceDiscovery discovery = factory.createDiscovery(url);
+
+        Assertions.assertTrue(discovery instanceof ZookeeperServiceDiscovery);
+    }
+}
diff --git a/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryTest.java b/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryTest.java
index 359d62ae0d..d311728542 100644
--- a/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryTest.java
+++ b/dubbo-registry/dubbo-registry-zookeeper/src/test/java/org/apache/dubbo/registry/zookeeper/ZookeeperServiceDiscoveryTest.java
@@ -18,23 +18,30 @@ package org.apache.dubbo.registry.zookeeper;
 
 import org.apache.dubbo.common.URL;
 import org.apache.dubbo.common.utils.NetUtils;
+import org.apache.dubbo.common.utils.Page;
 import org.apache.dubbo.event.EventDispatcher;
 import org.apache.dubbo.registry.client.DefaultServiceInstance;
 import org.apache.dubbo.registry.client.ServiceInstance;
 
 import org.apache.curator.test.TestingServer;
+import org.apache.dubbo.registry.client.event.ServiceInstancesChangedEvent;
+import org.apache.dubbo.registry.client.event.listener.ServiceInstancesChangedListener;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.mockito.internal.util.collections.Sets;
 
 import java.util.HashMap;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
 
 import static java.util.Arrays.asList;
 import static org.apache.dubbo.common.utils.NetUtils.getAvailablePort;
 import static org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.INSTANCE_REVISION_UPDATED_KEY;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
@@ -106,102 +113,103 @@ public class ZookeeperServiceDiscoveryTest {
         return new DefaultServiceInstance(serviceName, host, port);
     }
 
-//    @Test
-//    public void testGetInstances() throws InterruptedException {
-//
-//        List<ServiceInstance> instances = asList(
-//                createServiceInstance(SERVICE_NAME, LOCALHOST, 8080),
-//                createServiceInstance(SERVICE_NAME, LOCALHOST, 8081),
-//                createServiceInstance(SERVICE_NAME, LOCALHOST, 8082)
-//        );
-//
-//        instances.forEach(discovery::register);
-//
-//        List<ServiceInstance> serviceInstances = new LinkedList<>();
-//
-//        CountDownLatch latch = new CountDownLatch(1);
-//
-//        // Add Listener
-//        discovery.addServiceInstancesChangedListener(new ServiceInstancesChangedListener(SERVICE_NAME) {
-//            @Override
-//            public void onEvent(ServiceInstancesChangedEvent event) {
-//                serviceInstances.addAll(event.getServiceInstances());
-//                latch.countDown();
-//            }
-//        });
-//
-//        discovery.register(createServiceInstance(SERVICE_NAME, LOCALHOST, 8082));
-//        discovery.update(createServiceInstance(SERVICE_NAME, LOCALHOST, 8082));
-//
-//        latch.await();
-//
-//        assertFalse(serviceInstances.isEmpty());
-//
-//        // offset starts 0
-//        int offset = 0;
-//        // requestSize > total elements
-//        int requestSize = 5;
-//
-//        Page<ServiceInstance> page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(0, page.getOffset());
-//        assertEquals(5, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(3, page.getData().size());
-//        assertTrue(page.hasData());
-//
-//        for (ServiceInstance instance : page.getData()) {
-//            assertTrue(instances.contains(instance));
-//        }
-//
-//        // requestSize < total elements
-//        requestSize = 2;
-//
-//        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(0, page.getOffset());
-//        assertEquals(2, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(2, page.getData().size());
-//        assertTrue(page.hasData());
-//
-//        for (ServiceInstance instance : page.getData()) {
-//            assertTrue(instances.contains(instance));
-//        }
-//
-//        offset = 1;
-//        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(1, page.getOffset());
-//        assertEquals(2, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(2, page.getData().size());
-//        assertTrue(page.hasData());
-//
-//        for (ServiceInstance instance : page.getData()) {
-//            assertTrue(instances.contains(instance));
-//        }
-//
-//        offset = 2;
-//        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(2, page.getOffset());
-//        assertEquals(2, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(1, page.getData().size());
-//        assertTrue(page.hasData());
-//
-//        offset = 3;
-//        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(3, page.getOffset());
-//        assertEquals(2, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(0, page.getData().size());
-//        assertFalse(page.hasData());
-//
-//        offset = 5;
-//        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
-//        assertEquals(5, page.getOffset());
-//        assertEquals(2, page.getPageSize());
-//        assertEquals(3, page.getTotalSize());
-//        assertEquals(0, page.getData().size());
-//        assertFalse(page.hasData());
-//
-//    }
+    @Test
+    public void testGetInstances() throws InterruptedException {
+
+        List<ServiceInstance> instances = asList(
+                createServiceInstance(SERVICE_NAME, LOCALHOST, 8080),
+                createServiceInstance(SERVICE_NAME, LOCALHOST, 8081),
+                createServiceInstance(SERVICE_NAME, LOCALHOST, 8082)
+        );
+
+        instances.forEach(discovery::register);
+
+        List<ServiceInstance> serviceInstances = new LinkedList<>();
+
+        CountDownLatch latch = new CountDownLatch(1);
+
+        // Add Listener
+        discovery.addServiceInstancesChangedListener(
+                new ServiceInstancesChangedListener(Sets.newSet(SERVICE_NAME), discovery) {
+            @Override
+            public void onEvent(ServiceInstancesChangedEvent event) {
+                serviceInstances.addAll(event.getServiceInstances());
+                latch.countDown();
+            }
+        });
+
+        discovery.register(createServiceInstance(SERVICE_NAME, LOCALHOST, 8082));
+        discovery.update(createServiceInstance(SERVICE_NAME, LOCALHOST, 8082));
+
+        latch.await();
+
+        assertFalse(serviceInstances.isEmpty());
+
+        // offset starts 0
+        int offset = 0;
+        // requestSize > total elements
+        int requestSize = 5;
+
+        Page<ServiceInstance> page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(0, page.getOffset());
+        assertEquals(5, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(3, page.getData().size());
+        assertTrue(page.hasData());
+
+        for (ServiceInstance instance : page.getData()) {
+            assertTrue(instances.contains(instance));
+        }
+
+        // requestSize < total elements
+        requestSize = 2;
+
+        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(0, page.getOffset());
+        assertEquals(2, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(2, page.getData().size());
+        assertTrue(page.hasData());
+
+        for (ServiceInstance instance : page.getData()) {
+            assertTrue(instances.contains(instance));
+        }
+
+        offset = 1;
+        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(1, page.getOffset());
+        assertEquals(2, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(2, page.getData().size());
+        assertTrue(page.hasData());
+
+        for (ServiceInstance instance : page.getData()) {
+            assertTrue(instances.contains(instance));
+        }
+
+        offset = 2;
+        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(2, page.getOffset());
+        assertEquals(2, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(1, page.getData().size());
+        assertTrue(page.hasData());
+
+        offset = 3;
+        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(3, page.getOffset());
+        assertEquals(2, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(0, page.getData().size());
+        assertFalse(page.hasData());
+
+        offset = 5;
+        page = discovery.getInstances(SERVICE_NAME, offset, requestSize);
+        assertEquals(5, page.getOffset());
+        assertEquals(2, page.getPageSize());
+        assertEquals(3, page.getTotalSize());
+        assertEquals(0, page.getData().size());
+        assertFalse(page.hasData());
+
+    }
 }