add unit test for TraceTelnetHandler (#7909)

dubbo-plugin/dubbo-qos/src/test/java/org/apache/dubbo/qos/legacy/TraceTelnetHandlerTest.java

@@ -0,0 +1,81 @@
+/*
+ * 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.qos.legacy;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.qos.legacy.service.DemoService;
+import org.apache.dubbo.remoting.Channel;
+import org.apache.dubbo.remoting.telnet.TelnetHandler;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol;
+import org.apache.dubbo.rpc.protocol.dubbo.filter.TraceFilter;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.Field;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.reset;
+
+public class TraceTelnetHandlerTest {
+
+    private TelnetHandler handler;
+    private Channel mockChannel;
+    private Invoker<DemoService> mockInvoker;
+    private URL url = URL.valueOf("dubbo://127.0.0.1:20884/demo");
+
+    @BeforeEach
+    public void setUp() {
+        handler = new TraceTelnetHandler();
+        mockChannel = mock(Channel.class);
+        mockInvoker = mock(Invoker.class);
+        given(mockInvoker.getInterface()).willReturn(DemoService.class);
+        given(mockInvoker.getUrl()).willReturn(url);
+    }
+
+    @AfterEach
+    public void tearDown() {
+        reset(mockChannel, mockInvoker);
+        ProtocolUtils.closeAll();
+    }
+
+    @Test
+    public void testTraceTelnetAddTracer() throws Exception {
+        String method = "sayHello";
+        String message = "org.apache.dubbo.qos.legacy.service.DemoService sayHello 1";
+        Class<?> type = DemoService.class;
+
+        DubboProtocol.getDubboProtocol().export(mockInvoker);
+        handler.telnet(mockChannel, message);
+
+        String key = type.getName() + "." + method;
+        Field tracers = TraceFilter.class.getDeclaredField("TRACERS");
+        tracers.setAccessible(true);
+        ConcurrentHashMap<String, Set<Channel>> map =
+                (ConcurrentHashMap<String, Set<Channel>>) tracers.get(new ConcurrentHashMap<String, Set<Channel>>());
+
+        Set<Channel> channels = map.getOrDefault(key, null);
+        Assertions.assertNotNull(channels);
+
+        Assertions.assertTrue(channels.contains(mockChannel));
+    }
+}