[ISSUE #5522] add unit test for MetadataOperation (#5608)

* add unit test for MetadataOperation

* update method name

naming/src/test/java/com/alibaba/nacos/naming/core/v2/metadata/MetadataOperationTest.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.nacos.naming.core.v2.metadata;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class MetadataOperationTest {
+
+    private MetadataOperation<String> metadataOperation;
+
+    @Before
+    public void setUp() {
+        metadataOperation = new MetadataOperation();
+    }
+
+    @Test
+    public void testGetNamespace() {
+        String namespace = metadataOperation.getNamespace();
+
+        Assert.assertNull(namespace);
+    }
+
+    @Test
+    public void testSetNamespace() {
+        String namespace = "2398479283749823984";
+        metadataOperation.setNamespace(namespace);
+
+        Assert.assertEquals(metadataOperation.getNamespace(), namespace);
+    }
+
+    @Test
+    public void testGetGroup() {
+        String group = metadataOperation.getGroup();
+
+        Assert.assertNull(group);
+    }
+
+    @Test
+    public void testSetGroup() {
+        String group = "default";
+        metadataOperation.setGroup(group);
+
+        Assert.assertEquals(metadataOperation.getGroup(), group);
+    }
+
+    @Test
+    public void testGetServiceName() {
+        String serviceName = metadataOperation.getServiceName();
+
+        Assert.assertNull(serviceName);
+    }
+
+    @Test
+    public void testSetServiceName() {
+        String serviceName = "nacos";
+        metadataOperation.setServiceName(serviceName);
+
+        Assert.assertEquals(metadataOperation.getServiceName(), serviceName);
+    }
+
+    @Test
+    public void testGetTag() {
+        String tag = metadataOperation.getTag();
+
+        Assert.assertNull(tag);
+    }
+
+    @Test
+    public void testSetTag() {
+        String tag = "tag";
+        metadataOperation.setTag(tag);
+
+        Assert.assertEquals(metadataOperation.getTag(), tag);
+    }
+
+    @Test
+    public void testGetMetadata() {
+        Object metadata = metadataOperation.getMetadata();
+
+        Assert.assertNull(metadata);
+    }
+
+    @Test
+    public void testSetMetadata() {
+        String metadata = "metadata";
+        metadataOperation.setMetadata(metadata);
+
+        Assert.assertEquals(metadataOperation.getMetadata(), metadata);
+    }
+}