MINOR: Cleanups in Test Common Module (apache#19775)

sjhajharia · web-flow · commit 2fe447a8a392 · 2025-05-26T03:07:30.000+08:00
Now that Kafka Brokers support Java 17, this PR makes some changes in
test-common module. The changes mostly include:
- Collections.emptyList(), Collections.singletonList() and
Arrays.asList() are replaced with List.of()
- Collections.emptyMap() and Collections.singletonMap() are replaced
with Map.of()
- Collections.singleton() is replaced with Set.of()

Reviewers: Ken Huang &lt;s7133700@gmail.com&gt;, Chia-Ping Tsai
 &lt;chia7712@gmail.com&gt;
diff --git a/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/ClusterConfig.java b/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/ClusterConfig.java
@@ -207,10 +207,10 @@ public static class Builder {
         private ListenerName controllerListenerName;
         private File trustStoreFile;
         private MetadataVersion metadataVersion;
-        private Map<String, String> serverProperties = Collections.emptyMap();
-        private Map<Integer, Map<String, String>> perServerProperties = Collections.emptyMap();
-        private List<String> tags = Collections.emptyList();
-        private Map<Feature, Short> features = Collections.emptyMap();
+        private Map<String, String> serverProperties = Map.of();
+        private Map<Integer, Map<String, String>> perServerProperties = Map.of();
+        private List<String> tags = List.of();
+        private Map<Feature, Short> features = Map.of();
 
         private Builder() {}
 
diff --git a/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/ClusterTemplate.java b/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/ClusterTemplate.java
@@ -44,7 +44,7 @@
  * Usage looks something like this:
  * <pre>{@code
  * private static List<ClusterConfig> generator() {
- *     return Collections.singletonList(ClusterConfig.defaultBuilder().build());
+ *     return List.of(ClusterConfig.defaultBuilder().build());
  * }
  *
  * @ClusterTemplate("generator")
diff --git a/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/README.md b/test-common/test-common-internal-api/src/main/java/org/apache/kafka/common/test/api/README.md
@@ -79,7 +79,7 @@ references a static method on the test class. This method is used to produce any
 number of test configurations using a fluent builder style API.
 
 ```java
-import java.util.Arrays;
+import java.util.List;
 
 @ClusterTemplate("generateConfigs")
 void testSomething() { ... }
@@ -99,7 +99,7 @@ static List<ClusterConfig> generateConfigs() {
           .name("Generated Test 3")
           .serverProperties(props3)
           .build();
-  return Arrays.asList(config1, config2, config3);
+  return List.of(config1, config2, config3);
 }
 ```
 
diff --git a/test-common/test-common-internal-api/src/test/java/org/apache/kafka/common/test/api/ClusterConfigTest.java b/test-common/test-common-internal-api/src/test/java/org/apache/kafka/common/test/api/ClusterConfigTest.java
@@ -29,7 +29,6 @@
 import java.lang.reflect.Field;
 import java.nio.file.Files;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -55,20 +54,20 @@ public void testCopy() throws IOException {
         trustStoreFile.deleteOnExit();
 
         ClusterConfig clusterConfig = ClusterConfig.builder()
-                .setTypes(Collections.singleton(Type.KRAFT))
+                .setTypes(Set.of(Type.KRAFT))
                 .setBrokers(3)
                 .setControllers(2)
                 .setDisksPerBroker(1)
                 .setAutoStart(true)
-                .setTags(Arrays.asList("name", "Generated Test"))
+                .setTags(List.of("name", "Generated Test"))
                 .setBrokerSecurityProtocol(SecurityProtocol.PLAINTEXT)
                 .setBrokerListenerName(ListenerName.normalised("EXTERNAL"))
                 .setControllerSecurityProtocol(SecurityProtocol.SASL_PLAINTEXT)
                 .setControllerListenerName(ListenerName.normalised("CONTROLLER"))
                 .setTrustStoreFile(trustStoreFile)
                 .setMetadataVersion(MetadataVersion.MINIMUM_VERSION)
-                .setServerProperties(Collections.singletonMap("broker", "broker_value"))
-                .setPerServerProperties(Collections.singletonMap(0, Collections.singletonMap("broker_0", "broker_0_value")))
+                .setServerProperties(Map.of("broker", "broker_value"))
+                .setPerServerProperties(Map.of(0, Map.of("broker_0", "broker_0_value")))
                 .build();
 
         Map<String, Object> clusterConfigFields = fields(clusterConfig);
@@ -105,7 +104,7 @@ public void testDisksPerBrokerIsZero() {
 
     @Test
     public void testDisplayTags() {
-        List<String> tags = Arrays.asList("tag 1", "tag 2", "tag 3");
+        List<String> tags = List.of("tag 1", "tag 2", "tag 3");
         ClusterConfig clusterConfig = ClusterConfig.defaultBuilder().setTags(tags).build();
 
         Set<String> expectedDisplayTags = clusterConfig.displayTags();
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/ClusterInstance.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/ClusterInstance.java
@@ -57,7 +57,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -242,7 +241,7 @@ default Set<GroupProtocol> supportedGroupProtocols() {
         if (brokers().values().stream().allMatch(b -> b.dataPlaneRequestProcessor().isConsumerGroupProtocolEnabled())) {
             return Set.of(CLASSIC, CONSUMER);
         } else {
-            return Collections.singleton(CLASSIC);
+            return Set.of(CLASSIC);
         }
     }
 
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/KafkaClusterTestKit.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/KafkaClusterTestKit.java
@@ -60,7 +60,6 @@
 import java.util.AbstractMap.SimpleImmutableEntry;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -251,15 +250,15 @@ public KafkaClusterTestKit build() throws Exception {
                     socketFactoryManager.getOrCreatePortForListener(node.id(), brokerListenerName);
                 }
                 for (TestKitNode node : nodes.controllerNodes().values()) {
-                    setupNodeDirectories(baseDirectory, node.metadataDirectory(), Collections.emptyList());
+                    setupNodeDirectories(baseDirectory, node.metadataDirectory(), List.of());
                     KafkaConfig config = createNodeConfig(node);
                     SharedServer sharedServer = new SharedServer(
                         config,
                         node.initialMetaPropertiesEnsemble(),
                         Time.SYSTEM,
                         new Metrics(),
                         CompletableFuture.completedFuture(QuorumConfig.parseVoterConnections(config.quorumConfig().voters())),
-                        Collections.emptyList(),
+                        List.of(),
                         faultHandlerFactory,
                         socketFactoryManager.getOrCreateSocketFactory(node.id())
                     );
@@ -287,7 +286,7 @@ public KafkaClusterTestKit build() throws Exception {
                             Time.SYSTEM,
                             new Metrics(),
                             CompletableFuture.completedFuture(QuorumConfig.parseVoterConnections(config.quorumConfig().voters())),
-                            Collections.emptyList(),
+                            List.of(),
                             faultHandlerFactory,
                             socketFactoryManager.getOrCreateSocketFactory(node.id())
                         );
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/MockController.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/MockController.java
@@ -70,7 +70,6 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -388,7 +387,7 @@ private ApiError incrementalAlterResource(ConfigResource resource,
                         configs.computeIfAbsent(resource, __ -> new HashMap<>()).put(key, value);
                         break;
                     case DELETE:
-                        configs.getOrDefault(resource, Collections.emptyMap()).remove(key);
+                        configs.getOrDefault(resource, Map.of()).remove(key);
                         break;
                     default:
                         break;
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/PreboundSocketFactoryManager.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/PreboundSocketFactoryManager.java
@@ -23,7 +23,6 @@
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.nio.channels.ServerSocketChannel;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
@@ -174,7 +173,7 @@ public synchronized void close() throws Exception {
         // SocketServer.)
         for (Entry<Integer, Map<String, ServerSocketChannel>> socketsEntry : sockets.entrySet()) {
             Set<String> usedListeners = usedSockets.getOrDefault(
-                socketsEntry.getKey(), Collections.emptySet());
+                socketsEntry.getKey(), Set.of());
             for (Entry<String, ServerSocketChannel> entry : socketsEntry.getValue().entrySet()) {
                 if (!usedListeners.contains(entry.getKey())) {
                     Utils.closeQuietly(entry.getValue(), "serverSocketChannel");
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/TestKitNodes.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/TestKitNodes.java
@@ -52,7 +52,7 @@ public static class Builder {
         private int numControllerNodes;
         private int numBrokerNodes;
         private int numDisksPerBroker = 1;
-        private Map<Integer, Map<String, String>> perServerProperties = Collections.emptyMap();
+        private Map<Integer, Map<String, String>> perServerProperties = Map.of();
         private BootstrapMetadata bootstrapMetadata;
 
         public Builder() {
@@ -201,7 +201,7 @@ public TestKitNodes build() {
                     baseDirectory.toFile().getAbsolutePath(),
                     clusterId,
                     brokerNodeIds.contains(id),
-                    perServerProperties.getOrDefault(id, Collections.emptyMap())
+                    perServerProperties.getOrDefault(id, Map.of())
                 );
                 controllerNodes.put(id, controllerNode);
             }
@@ -213,7 +213,7 @@ public TestKitNodes build() {
                     baseDirectory.toFile().getAbsolutePath(),
                     clusterId,
                     controllerNodeIds.contains(id),
-                    perServerProperties.getOrDefault(id, Collections.emptyMap()),
+                    perServerProperties.getOrDefault(id, Map.of()),
                     numDisksPerBroker
                 );
                 brokerNodes.put(id, brokerNode);
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/TestUtils.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/TestUtils.java
@@ -32,7 +32,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
-import java.util.Collections;
+import java.util.List;
 import java.util.Optional;
 import java.util.Random;
 import java.util.function.BiFunction;
@@ -180,7 +180,7 @@ public static int waitUntilLeaderIsElectedOrChangedWithAdmin(Admin admin,
     }
 
     private static Integer getLeaderFromAdmin(Admin admin, String topic, int partition) throws Exception {
-        TopicDescription topicDescription = admin.describeTopics(Collections.singletonList(topic)).allTopicNames().get().get(topic);
+        TopicDescription topicDescription = admin.describeTopics(List.of(topic)).allTopicNames().get().get(topic);
         return topicDescription.partitions().stream()
             .filter(partitionInfo -> partitionInfo.partition() == partition)
             .findFirst()
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/junit/ClusterTestExtensions.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/junit/ClusterTestExtensions.java
@@ -42,7 +42,6 @@
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -268,7 +267,7 @@ private List<TestTemplateInvocationContext> processClusterTestInternal(
             .collect(Collectors.toMap(ClusterFeature::feature, ClusterFeature::version));
 
         ClusterConfig config = ClusterConfig.builder()
-            .setTypes(new HashSet<>(Arrays.asList(types)))
+            .setTypes(Set.of(types))
             .setBrokers(clusterTest.brokers() == 0 ? defaults.brokers() : clusterTest.brokers())
             .setControllers(clusterTest.controllers() == 0 ? defaults.controllers() : clusterTest.controllers())
             .setDisksPerBroker(clusterTest.disksPerBroker() == 0 ? defaults.disksPerBroker() : clusterTest.disksPerBroker())
@@ -280,7 +279,7 @@ private List<TestTemplateInvocationContext> processClusterTestInternal(
             .setServerProperties(serverProperties)
             .setPerServerProperties(perServerProperties)
             .setMetadataVersion(clusterTest.metadataVersion())
-            .setTags(Arrays.asList(clusterTest.tags()))
+            .setTags(List.of(clusterTest.tags()))
             .setFeatures(features)
             .build();
 
diff --git a/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/junit/RaftClusterInvocationContext.java b/test-common/test-common-runtime/src/main/java/org/apache/kafka/common/test/junit/RaftClusterInvocationContext.java
@@ -42,7 +42,6 @@
 import org.junit.jupiter.api.extension.Extension;
 import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
 
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -55,8 +54,6 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-
-
 /**
  * Wraps a {@link KafkaClusterTestKit} inside lifecycle methods for a test invocation. Each instance of this
  * class is provided with a configuration for the cluster.
@@ -88,7 +85,7 @@ public String getDisplayName(int invocationIndex) {
     @Override
     public List<Extension> getAdditionalExtensions() {
         RaftClusterInstance clusterInstance = new RaftClusterInstance(clusterConfig, isCombined);
-        return Arrays.asList(
+        return List.of(
                 (BeforeEachCallback) context -> {
                     clusterInstance.format();
                     if (clusterConfig.isAutoStart()) {
diff --git a/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/KafkaClusterTestKitTest.java b/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/KafkaClusterTestKitTest.java
@@ -23,10 +23,7 @@
 
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -42,11 +39,11 @@ public class KafkaClusterTestKitTest {
     @ValueSource(ints = {0, -1})
     public void testCreateClusterWithBadNumDisksThrows(int disks) {
         IllegalArgumentException e = assertThrowsExactly(IllegalArgumentException.class, () -> new KafkaClusterTestKit.Builder(
-                new TestKitNodes.Builder()
-                        .setNumBrokerNodes(1)
-                        .setNumDisksPerBroker(disks)
-                        .setNumControllerNodes(1)
-                        .build())
+            new TestKitNodes.Builder()
+                .setNumBrokerNodes(1)
+                .setNumDisksPerBroker(disks)
+                .setNumControllerNodes(1)
+                .build())
         );
         assertEquals("Invalid value for numDisksPerBroker", e.getMessage());
     }
@@ -76,15 +73,15 @@ public void testCreateClusterWithBadNumOfBrokers() {
     @Test
     public void testCreateClusterWithBadPerServerProperties() {
         Map<Integer, Map<String, String>> perServerProperties = new HashMap<>();
-        perServerProperties.put(100, Collections.singletonMap("foo", "foo1"));
-        perServerProperties.put(200, Collections.singletonMap("bar", "bar1"));
+        perServerProperties.put(100, Map.of("foo", "foo1"));
+        perServerProperties.put(200, Map.of("bar", "bar1"));
 
         IllegalArgumentException e = assertThrowsExactly(IllegalArgumentException.class, () -> new KafkaClusterTestKit.Builder(
-                new TestKitNodes.Builder()
-                        .setNumBrokerNodes(1)
-                        .setNumControllerNodes(1)
-                        .setPerServerProperties(perServerProperties)
-                        .build())
+            new TestKitNodes.Builder()
+                .setNumBrokerNodes(1)
+                .setNumControllerNodes(1)
+                .setPerServerProperties(perServerProperties)
+                .build())
         );
         assertEquals("Unknown server id 100, 200 in perServerProperties, the existent server ids are 0, 3000", e.getMessage());
     }
@@ -93,27 +90,27 @@ public void testCreateClusterWithBadPerServerProperties() {
     @ValueSource(booleans = {true, false})
     public void testCreateClusterAndCloseWithMultipleLogDirs(boolean combined) throws Exception {
         try (KafkaClusterTestKit cluster = new KafkaClusterTestKit.Builder(
-                new TestKitNodes.Builder().
-                        setNumBrokerNodes(5).
-                        setNumDisksPerBroker(2).
-                        setCombined(combined).
-                        setNumControllerNodes(3).build()).build()) {
+            new TestKitNodes.Builder().
+                setNumBrokerNodes(5).
+                setNumDisksPerBroker(2).
+                setCombined(combined).
+                setNumControllerNodes(3).build()).build()) {
 
             TestKitNodes nodes = cluster.nodes();
             assertEquals(5, nodes.brokerNodes().size());
             assertEquals(3, nodes.controllerNodes().size());
 
             nodes.brokerNodes().forEach((brokerId, node) -> {
                 assertEquals(2, node.logDataDirectories().size());
-                Set<String> expected = new HashSet<>(Arrays.asList(String.format("broker_%d_data0", brokerId), String.format("broker_%d_data1", brokerId)));
+                Set<String> expected = Set.of(String.format("broker_%d_data0", brokerId), String.format("broker_%d_data1", brokerId));
                 if (nodes.isCombined(node.id())) {
-                    expected = new HashSet<>(Arrays.asList(String.format("combined_%d_0", brokerId), String.format("combined_%d_1", brokerId)));
+                    expected = Set.of(String.format("combined_%d_0", brokerId), String.format("combined_%d_1", brokerId));
                 }
                 assertEquals(
-                        expected,
-                        node.logDataDirectories().stream()
-                                .map(p -> Paths.get(p).getFileName().toString())
-                                .collect(Collectors.toSet())
+                    expected,
+                    node.logDataDirectories().stream()
+                        .map(p -> Paths.get(p).getFileName().toString())
+                        .collect(Collectors.toSet())
                 );
             });
 
@@ -128,18 +125,19 @@ public void testCreateClusterAndCloseWithMultipleLogDirs(boolean combined) throw
     public void testCreateClusterWithSpecificBaseDir() throws Exception {
         Path baseDirectory = TestUtils.tempDirectory().toPath();
         try (KafkaClusterTestKit cluster = new KafkaClusterTestKit.Builder(
-                new TestKitNodes.Builder().
-                        setBaseDirectory(baseDirectory).
-                        setNumBrokerNodes(1).
-                        setCombined(true).
-                        setNumControllerNodes(1).build()).build()) {
+            new TestKitNodes.Builder().
+                setBaseDirectory(baseDirectory).
+                setNumBrokerNodes(1).
+                setCombined(true).
+                setNumControllerNodes(1).build()).build()) {
             assertEquals(cluster.nodes().baseDirectory(), baseDirectory.toFile().getAbsolutePath());
             cluster.nodes().controllerNodes().values().forEach(controller ->
                 assertTrue(Paths.get(controller.metadataDirectory()).startsWith(baseDirectory)));
             cluster.nodes().brokerNodes().values().forEach(broker ->
                 assertTrue(Paths.get(broker.metadataDirectory()).startsWith(baseDirectory)));
         }
     }
+
     @Test
     public void testExposedFaultHandlers() {
         TestKitNodes nodes = new TestKitNodes.Builder()
diff --git a/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/TestKitNodeTest.java b/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/TestKitNodeTest.java
diff --git a/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/junit/ClusterTestExtensionsTest.java b/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/junit/ClusterTestExtensionsTest.java
diff --git a/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/junit/ClusterTestExtensionsUnitTest.java b/test-common/test-common-runtime/src/test/java/org/apache/kafka/common/test/junit/ClusterTestExtensionsUnitTest.java
diff --git a/test-common/test-common-util/src/test/java/org/apache/kafka/common/test/junit/CatalogTestFilterTest.java b/test-common/test-common-util/src/test/java/org/apache/kafka/common/test/junit/CatalogTestFilterTest.java

Original file line number	Diff line number	Diff line change
`@@ -44,7 +44,7 @@`
`44`	`44`	`* Usage looks something like this:`
`45`	`45`	`* <pre>{@code`
`46`	`46`	`* private static List<ClusterConfig> generator() {`
`47`		`- * return Collections.singletonList(ClusterConfig.defaultBuilder().build());`
	`47`	`+ * return List.of(ClusterConfig.defaultBuilder().build());`
`48`	`48`	`* }`
`49`	`49`	`*`
`50`	`50`	`* @ClusterTemplate("generator")`