diff --git a/handlers/handler-governance/src/test/java/org/apache/servicecomb/handler/governance/TestInstanceIsolationDiscoveryFilter.java b/handlers/handler-governance/src/test/java/org/apache/servicecomb/handler/governance/TestInstanceIsolationDiscoveryFilter.java
new file mode 100644
index 0000000000..155c3380e1
--- /dev/null
+++ b/handlers/handler-governance/src/test/java/org/apache/servicecomb/handler/governance/TestInstanceIsolationDiscoveryFilter.java
@@ -0,0 +1,95 @@
+/*
+ * 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.servicecomb.handler.governance;
+
+import java.time.Duration;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.servicecomb.core.Invocation;
+import org.apache.servicecomb.core.SCBEngine;
+import org.apache.servicecomb.core.Transport;
+import org.apache.servicecomb.core.registry.discovery.EndpointDiscoveryFilter;
+import org.apache.servicecomb.core.transport.TransportManager;
+import org.apache.servicecomb.foundation.common.cache.VersionedCache;
+import org.apache.servicecomb.foundation.common.event.EventManager;
+import org.apache.servicecomb.registry.DiscoveryManager;
+import org.apache.servicecomb.registry.api.registry.MicroserviceInstance;
+import org.apache.servicecomb.registry.api.registry.MicroserviceInstanceStatus;
+import org.apache.servicecomb.registry.cache.InstanceCacheManager;
+import org.apache.servicecomb.registry.discovery.DiscoveryContext;
+import org.apache.servicecomb.registry.discovery.DiscoveryTree;
+import org.apache.servicecomb.registry.discovery.DiscoveryTreeNode;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+public class TestInstanceIsolationDiscoveryFilter {
+  @Test
+  @SuppressWarnings("unchecked")
+  public void test_instance_isolation_correct() throws Exception {
+    DiscoveryTree discoveryTree = new DiscoveryTree();
+    DiscoveryContext discoveryContext = new DiscoveryContext();
+    discoveryTree.addFilter(new InstanceIsolationDiscoveryFilter());
+    discoveryTree.addFilter(new EndpointDiscoveryFilter());
+
+    Invocation invocation = Mockito.mock(Invocation.class);
+    discoveryContext.setInputParameters(invocation);
+    Mockito.when(invocation.getConfigTransportName()).thenReturn("rest");
+
+    TransportManager transportManager = Mockito.mock(TransportManager.class);
+    SCBEngine.getInstance().setTransportManager(transportManager);
+    Transport transport = Mockito.mock(Transport.class);
+    Mockito.when(transportManager.findTransport("rest")).thenReturn(transport);
+    Mockito.when(transport.parseAddress("rest://localhost:9090")).thenReturn("9090");
+    Mockito.when(transport.parseAddress("rest://localhost:9091")).thenReturn("9091");
+
+    Map<String, MicroserviceInstance> service1 = new HashMap<>();
+    MicroserviceInstance instance1 = Mockito.mock(MicroserviceInstance.class);
+    MicroserviceInstance instance2 = Mockito.mock(MicroserviceInstance.class);
+    Mockito.when(instance1.getInstanceId()).thenReturn("instance1");
+    Mockito.when(instance1.getStatus()).thenReturn(MicroserviceInstanceStatus.UP);
+    Mockito.when(instance1.getEndpoints()).thenReturn(Collections.singletonList("rest://localhost:9090"));
+    Mockito.when(instance2.getInstanceId()).thenReturn("instance2");
+    Mockito.when(instance2.getStatus()).thenReturn(MicroserviceInstanceStatus.UP);
+    Mockito.when(instance2.getEndpoints()).thenReturn(Collections.singletonList("rest://localhost:9092"));
+    service1.put(instance1.getInstanceId(), instance1);
+    service1.put(instance2.getInstanceId(), instance2);
+
+    InstanceCacheManager instanceCacheManager = Mockito.mock(InstanceCacheManager.class);
+    DiscoveryManager.INSTANCE = Mockito.spy(DiscoveryManager.INSTANCE);
+    Mockito.when(DiscoveryManager.INSTANCE.getInstanceCacheManager()).thenReturn(instanceCacheManager);
+
+    VersionedCache expects0 = new VersionedCache().autoCacheVersion().name("0+").data(service1);
+    Mockito.when(instanceCacheManager.getOrCreateVersionedCache("app", "service1",
+        "0+")).thenReturn(expects0);
+
+    DiscoveryTreeNode result = discoveryTree.discovery(discoveryContext, "app", "service1", "0+");
+    Assertions.assertEquals(2, ((List<Object>) result.data()).size());
+
+    // isolate
+    EventManager.post(new InstanceIsolatedEvent("instance1", Duration.ofMillis(8)));
+    result = discoveryTree.discovery(discoveryContext, "app", "service1", "0+");
+    Assertions.assertEquals(1, ((List<Object>) result.data()).size());
+    //recover
+    Thread.sleep(10);
+    result = discoveryTree.discovery(discoveryContext, "app", "service1", "0+");
+    Assertions.assertEquals(2, ((List<Object>) result.data()).size());
+  }
+}