[ISSUE apache#8586] Add more test coverage for SelectMessageQueueByRa…

…ndom (apache#8587)

client/src/test/java/org/apache/rocketmq/client/producer/selector/SelectMessageQueueByRandomTest.java

@@ -0,0 +1,74 @@
+/*
+ * 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.rocketmq.client.producer.selector;
+
+import org.apache.rocketmq.common.message.Message;
+import org.apache.rocketmq.common.message.MessageQueue;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThrows;
+
+public class SelectMessageQueueByRandomTest {
+
+    private final SelectMessageQueueByRandom selector = new SelectMessageQueueByRandom();
+
+    private final String defaultBroker = "defaultBroker";
+
+    private final String defaultTopic = "defaultTopic";
+
+    @Test
+    public void testSelectRandomMessageQueue() {
+        List<MessageQueue> messageQueues = createMessageQueues(10);
+        Message message = new Message(defaultTopic, "tag", "key", "body".getBytes());
+        MessageQueue selectedQueue = selector.select(messageQueues, message, null);
+        assertNotNull(selectedQueue);
+        assertEquals(messageQueues.size(), 10);
+        assertEquals(defaultTopic, selectedQueue.getTopic());
+        assertEquals(defaultBroker, selectedQueue.getBrokerName());
+    }
+
+    @Test
+    public void testSelectEmptyMessageQueue() {
+        List<MessageQueue> emptyQueues = new ArrayList<>();
+        Message message = new Message(defaultTopic, "tag", "key", "body".getBytes());
+        assertThrows(IllegalArgumentException.class, () -> selector.select(emptyQueues, message, null));
+    }
+
+    @Test
+    public void testSelectSingleMessageQueue() {
+        List<MessageQueue> singleQueueList = createMessageQueues(1);
+        Message message = new Message(defaultTopic, "tag", "key", "body".getBytes());
+        MessageQueue selectedQueue = selector.select(singleQueueList, message, null);
+        assertNotNull(selectedQueue);
+        assertEquals(defaultTopic, selectedQueue.getTopic());
+        assertEquals(defaultBroker, selectedQueue.getBrokerName());
+        assertEquals(singleQueueList.get(0).getQueueId(), selectedQueue.getQueueId());
+    }
+
+    private List<MessageQueue> createMessageQueues(final int count) {
+        List<MessageQueue> result = new ArrayList<>();
+        for (int i = 0; i < count; i++) {
+            result.add(new MessageQueue(defaultTopic, defaultBroker, i));
+        }
+        return result;
+    }
+}