Add unit test for TraceFilter (apache#7898)

* Add unit test for TraceFilter (apache#7876)

* println actual message (apache#7876)

* Fix TraceFilterTest#testInvoke (apache#7876)

dubbo-rpc/dubbo-rpc-dubbo/src/test/java/org/apache/dubbo/rpc/protocol/dubbo/filter/MockChannel.java

@@ -0,0 +1,121 @@
+/*
+ * 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.rpc.protocol.dubbo.filter;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.remoting.Channel;
+import org.apache.dubbo.remoting.ChannelHandler;
+import org.apache.dubbo.remoting.RemotingException;
+
+import java.net.InetSocketAddress;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+public class MockChannel implements Channel {
+
+    private Map<String, Object> attributes = new HashMap<>();
+    private List<Object> receivedObjects = new LinkedList<>();
+    private URL url;
+
+    public MockChannel() {
+    }
+
+    public MockChannel(URL url) {
+        this.url = url;
+    }
+
+    @Override
+    public InetSocketAddress getRemoteAddress() {
+        return null;
+    }
+
+    @Override
+    public boolean isConnected() {
+        return true;
+    }
+
+    @Override
+    public boolean hasAttribute(String key) {
+        return attributes.containsKey(key);
+    }
+
+    @Override
+    public Object getAttribute(String key) {
+        return attributes.getOrDefault(key, null);
+    }
+
+    @Override
+    public void setAttribute(String key, Object value) {
+        attributes.put(key, value);
+    }
+
+    @Override
+    public void removeAttribute(String key) {
+        attributes.remove(key);
+    }
+
+    @Override
+    public URL getUrl() {
+        return url;
+    }
+
+    @Override
+    public ChannelHandler getChannelHandler() {
+        return null;
+    }
+
+    @Override
+    public InetSocketAddress getLocalAddress() {
+        return null;
+    }
+
+    @Override
+    public void send(Object message) throws RemotingException {
+        receivedObjects.add(message);
+    }
+
+    @Override
+    public void send(Object message, boolean sent) throws RemotingException {
+        receivedObjects.add(message);
+    }
+
+    @Override
+    public void close() {
+
+    }
+
+    @Override
+    public void close(int timeout) {
+
+    }
+
+    @Override
+    public void startClose() {
+
+    }
+
+    @Override
+    public boolean isClosed() {
+        return false;
+    }
+
+    public List<Object> getReceivedObjects() {
+        return receivedObjects;
+    }
+}

dubbo-rpc/dubbo-rpc-dubbo/src/test/java/org/apache/dubbo/rpc/protocol/dubbo/filter/TraceFilterTest.java

@@ -0,0 +1,137 @@
+/*
+ * 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.rpc.protocol.dubbo.filter;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.common.utils.CollectionUtils;
+import org.apache.dubbo.remoting.Channel;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.protocol.dubbo.support.DemoService;
+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.List;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+public class TraceFilterTest {
+
+    private MockChannel mockChannel;
+    private static final String TRACE_MAX = "trace.max";
+    private static final String TRACE_COUNT = "trace.count";
+    private static final String TRACERS_FIELD_NAME = "TRACERS";
+
+    @BeforeEach
+    public void setUp() {
+        URL url = URL.valueOf("dubbo://127.0.0.1:20884/demo");
+        mockChannel = new MockChannel(url);
+    }
+
+    @AfterEach
+    public void tearDown() {
+        mockChannel.close();
+    }
+
+    @Test
+    public void testAddAndRemoveTracer() throws Exception {
+        String method = "sayHello";
+        Class<?> type = DemoService.class;
+        String key = type.getName() + "." + method;
+
+        // add tracer
+        TraceFilter.addTracer(type, method, mockChannel, 100);
+
+        Assertions.assertEquals(100, mockChannel.getAttribute(TRACE_MAX));
+        Assertions.assertTrue(mockChannel.getAttribute(TRACE_COUNT) instanceof AtomicInteger);
+
+        Field tracers = TraceFilter.class.getDeclaredField(TRACERS_FIELD_NAME);
+        tracers.setAccessible(true);
+        ConcurrentHashMap<String, Set<Channel>> o = (ConcurrentHashMap<String, Set<Channel>>) tracers.get(new ConcurrentHashMap<String, Set<Channel>>());
+
+        Assertions.assertTrue(o.containsKey(key));
+        Set<Channel> channels = o.get(key);
+        Assertions.assertNotNull(channels);
+        Assertions.assertTrue(channels.contains(mockChannel));
+
+        // remove tracer
+        TraceFilter.removeTracer(type, method, mockChannel);
+        Assertions.assertNull(mockChannel.getAttribute(TRACE_MAX));
+        Assertions.assertNull(mockChannel.getAttribute(TRACE_COUNT));
+        Assertions.assertFalse(channels.contains(mockChannel));
+    }
+
+    @Test
+    public void testInvoke() throws Exception {
+        String method = "sayHello";
+        Class<?> type = DemoService.class;
+        String key = type.getName() + "." + method;
+        // add tracer
+        TraceFilter.addTracer(type, method, mockChannel, 2);
+
+        Invoker<DemoService> mockInvoker = mock(Invoker.class);
+        Invocation mockInvocation = mock(Invocation.class);
+        Result mockResult = mock(Result.class);
+        TraceFilter filter = new TraceFilter();
+
+        given(mockInvoker.getInterface()).willReturn(DemoService.class);
+        given(mockInvocation.getMethodName()).willReturn(method);
+        given(mockInvocation.getArguments()).willReturn(new Object[0]);
+        given(mockInvoker.invoke(mockInvocation)).willReturn(mockResult);
+        given(mockResult.getValue()).willReturn("result");
+
+        // test invoke
+        filter.invoke(mockInvoker, mockInvocation);
+        String message = listToString(mockChannel.getReceivedObjects());
+        String expectMessage = "org.apache.dubbo.rpc.protocol.dubbo.support.DemoService.sayHello([]) -> \"result\"";
+        System.out.println("actual message: " + message);
+        Assertions.assertTrue(message.contains(expectMessage));
+        Assertions.assertTrue(message.contains("elapsed:"));
+        AtomicInteger traceCount = (AtomicInteger) mockChannel.getAttribute(TRACE_COUNT);
+        Assertions.assertEquals(1, traceCount.get());
+
+        // test remove channel when count >= max - 1
+        filter.invoke(mockInvoker, mockInvocation);
+        Field tracers = TraceFilter.class.getDeclaredField(TRACERS_FIELD_NAME);
+        tracers.setAccessible(true);
+        ConcurrentHashMap<String, Set<Channel>> o = (ConcurrentHashMap<String, Set<Channel>>) tracers.get(new ConcurrentHashMap<String, Set<Channel>>());
+        Assertions.assertTrue(o.containsKey(key));
+        Set<Channel> channels = o.get(key);
+        Assertions.assertNotNull(channels);
+        Assertions.assertFalse(channels.contains(mockChannel));
+    }
+
+    private static String listToString(List<Object> objectList) {
+        StringBuilder sb = new StringBuilder();
+        if (CollectionUtils.isEmpty(objectList)) {
+            return "";
+        }
+
+        objectList.forEach(o -> {
+            sb.append(o.toString());
+        });
+        return sb.toString();
+    }
+}