KAFKA-16475: add test for TopicImageNodeTest (apache#15720)

Add a unit test for TopicImageNodeTest.

Co-authored-by: Johnny Hsu <[email protected]>
Reviewers: Colin P. McCabe <[email protected]>

metadata/src/test/java/org/apache/kafka/image/node/TopicImageNodeTest.java

@@ -0,0 +1,60 @@
+/*
+ * 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.kafka.image.node;
+
+import org.apache.kafka.common.Uuid;
+import org.apache.kafka.image.TopicImage;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+
+@Timeout(value = 40)
+public class TopicImageNodeTest {
+    private final static TopicImageNode NODE = new TopicImageNode(new TopicImage("topic-image-node-test-topic", Uuid.ZERO_UUID, Collections.emptyMap()));
+
+    @Test
+    public void testChildNames() {
+        assertEquals(Arrays.asList("name", "id"), NODE.childNames());
+    }
+
+    @Test
+    public void testNameChild() {
+        MetadataNode child = NODE.child("name");
+        assertNotNull(child);
+        assertEquals(MetadataLeafNode.class, child.getClass());
+    }
+
+    @Test
+    public void testIdChild() {
+        MetadataNode child = NODE.child("id");
+        assertNotNull(child);
+        assertEquals(MetadataLeafNode.class, child.getClass());
+    }
+
+    @Test
+    public void testUnknownChild() {
+        assertNull(NODE.child("unknown"));
+    }
+}