[ISSUE #860] Add unit test for MetricsPluginFactory class (#3790)

* Add unit test for MetricsPluginFactory class

* Add end of line

eventmesh-metrics-plugin/eventmesh-metrics-api/build.gradle

@@ -25,4 +25,7 @@ dependencies {
 
     testCompileOnly 'org.projectlombok:lombok'
     testAnnotationProcessor 'org.projectlombok:lombok'
+
+    testImplementation "org.mockito:mockito-core"
+    testImplementation "org.mockito:mockito-inline"
 }

eventmesh-metrics-plugin/eventmesh-metrics-api/src/test/java/org/apache/eventmesh/metrics/api/MetricsPluginFactoryTest.java

@@ -0,0 +1,30 @@
+/*
+ * 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.eventmesh.metrics.api;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class MetricsPluginFactoryTest {
+
+    @Test
+    public void testGetMetricsRegistry_throwException() {
+        Exception exception = Assert.assertThrows(NullPointerException.class, () -> MetricsPluginFactory.getMetricsRegistry("security"));
+        Assert.assertTrue(exception.getMessage().contains("is not supported"));
+    }
+}

eventmesh-metrics-plugin/eventmesh-metrics-api/src/test/java/org/apache/eventmesh/metrics/api/model/GrpcSummaryMetricsTest.java

@@ -15,9 +15,7 @@
  * limitations under the License.
  */
 
-package org.apache.eventmesh.metrics.api;
-
-import org.apache.eventmesh.metrics.api.model.GrpcSummaryMetrics;
+package org.apache.eventmesh.metrics.api.model;
 
 import org.junit.Assert;
 import org.junit.Test;