Adopt naming conventions for constant fields

CONTRIBUTING.md

@@ -54,6 +54,8 @@ I hereby agree to the terms of the JUnit Contributor License Agreement.
 
 ### Naming Conventions
 
+Acronym are words.
+
 Whenever an acronym is included as part of a type name or method name, keep the first
 letter of the acronym uppercase and use lowercase for the rest of the acronym. Otherwise,
 it becomes _impossible_ to perform camel-cased searches in IDEs, and it becomes
@@ -119,6 +121,17 @@ code -- class names, method names, variable names, etc.
 See [`ExtensionContext`](junit-jupiter-api/src/main/java/org/junit/jupiter/api/extension/ExtensionContext.java) and
 [`ParameterContext`](junit-jupiter-api/src/main/java/org/junit/jupiter/api/extension/ParameterContext.java) for example Javadoc.
 
+### Constant fields
+
+A constant field is a `static final` field whose value is immutable. If a static final
+field has a primitive type or an immutable reference type it is a constant field.
+
+- To minimize accessibility and mutability for all non-private `static final` fields
+  under `src/main` should be constant fields.
+- Constant fields should be named using uppercase words separated by underscores. For
+  example `DEFAULT_HTTP_URL_PROVIDER`.
+
+Note: `org.junit.platform.commons.logging.Logger` is considered mutable.
 
 ### Nullability
 

documentation/src/tools/java/org/junit/api/tools/ApiReportGenerator.java

@@ -48,7 +48,7 @@
  */
 class ApiReportGenerator {
 
-	private static final Logger LOGGER = LoggerFactory.getLogger(ApiReportGenerator.class);
+	private static final Logger logger = LoggerFactory.getLogger(ApiReportGenerator.class);
 	private static final String EOL = System.lineSeparator();
 
 	public static void main(String... args) {
@@ -160,7 +160,7 @@ private static SortedSet<ClassInfo> collectTypes(ScanResult scanResult) {
 				.filter(it -> !it.getAnnotationInfo(API.class).isInherited()) //
 				.collect(toCollection(TreeSet::new));
 
-		LOGGER.debug(() -> {
+		logger.debug(() -> {
 			var builder = new StringBuilder("Listing of all " + types.size() + " annotated types:");
 			builder.append(EOL);
 			types.forEach(e -> builder.append(e.getName()).append(EOL));

gradle/config/checkstyle/checkstyleMain.xml

@@ -48,6 +48,20 @@
 		<module name="EqualsAvoidNull"/>
 		<module name="EmptyStatement"/>
 		<module name="MissingDeprecated"/>
+		<!-- non-private static final fields must be constants and named accordingly.
+		 	 See CONTRIBUTING.md - Constant fields -->
+		<module name="ConstantName">
+			<property name="applyToPrivate" value="false"/>
+		</module>
+		<module name="ConstantName">
+			<!-- private static final fields may be mutable or immutable.
+				 And a logger is always mutable. See CONTRIBUTING.md - Constant fields -->
+			<property name="format" value="^(?!^LOGGER$).*$"/>
+			<property name="applyToPublic" value="false"/>
+			<property name="applyToProtected" value="false"/>
+			<property name="applyToPackage" value="false"/>
+		</module>
+
 	</module>
 
 	<module name="JavadocPackage" />

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/descriptor/AbstractExtensionContext.java

@@ -54,7 +54,7 @@
  */
 abstract class AbstractExtensionContext<T extends TestDescriptor> implements ExtensionContextInternal, AutoCloseable {
 
-	private static final Logger LOGGER = LoggerFactory.getLogger(AbstractExtensionContext.class);
+	private static final Logger logger = LoggerFactory.getLogger(AbstractExtensionContext.class);
 	private static final Namespace CLOSEABLE_RESOURCE_LOGGING_NAMESPACE = Namespace.create(
 		AbstractExtensionContext.class, "CloseableResourceLogging");
 
@@ -113,7 +113,7 @@ private <N> NamespacedHierarchicalStore.CloseAction<N> createCloseAction() {
 			if (value instanceof Store.CloseableResource resource) {
 				if (isAutoCloseEnabled) {
 					store.computeIfAbsent(value.getClass(), type -> {
-						LOGGER.warn(() -> "Type implements CloseableResource but not AutoCloseable: " + type.getName());
+						logger.warn(() -> "Type implements CloseableResource but not AutoCloseable: " + type.getName());
 						return true;
 					});
 				}

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/TempDirectory.java

@@ -273,7 +273,7 @@ private static ExtensionContext.Store getContextSpecificStore(ExtensionContext c
 	@SuppressWarnings("deprecation")
 	static class CloseablePath implements Store.CloseableResource, AutoCloseable {
 
-		private static final Logger LOGGER = LoggerFactory.getLogger(CloseablePath.class);
+		private static final Logger logger = LoggerFactory.getLogger(CloseablePath.class);
 
 		private final Path dir;
 		private final TempDirFactory factory;
@@ -311,26 +311,26 @@ public void close() throws IOException {
 			try {
 				if (this.cleanupMode == NEVER
 						|| (this.cleanupMode == ON_SUCCESS && selfOrChildFailed(this.extensionContext))) {
-					LOGGER.info(() -> "Skipping cleanup of temp dir %s for %s due to CleanupMode.%s.".formatted(
+					logger.info(() -> "Skipping cleanup of temp dir %s for %s due to CleanupMode.%s.".formatted(
 						this.dir, descriptionFor(this.annotatedElement), this.cleanupMode.name()));
 					return;
 				}
 
 				FileOperations fileOperations = this.extensionContext.getStore(NAMESPACE) //
 						.getOrDefault(FILE_OPERATIONS_KEY, FileOperations.class, FileOperations.DEFAULT);
 				FileOperations loggingFileOperations = file -> {
-					LOGGER.trace(() -> "Attempting to delete " + file);
+					logger.trace(() -> "Attempting to delete " + file);
 					try {
 						fileOperations.delete(file);
-						LOGGER.trace(() -> "Successfully deleted " + file);
+						logger.trace(() -> "Successfully deleted " + file);
 					}
 					catch (IOException e) {
-						LOGGER.trace(e, () -> "Failed to delete " + file);
+						logger.trace(e, () -> "Failed to delete " + file);
 						throw e;
 					}
 				};
 
-				LOGGER.trace(() -> "Cleaning up temp dir " + this.dir);
+				logger.trace(() -> "Cleaning up temp dir " + this.dir);
 				SortedMap<Path, IOException> failures = deleteAllFilesAndDirectories(loggingFileOperations);
 				if (!failures.isEmpty()) {
 					throw createIOExceptionWithAttachedFailures(failures);
@@ -383,7 +383,7 @@ private SortedMap<Path, IOException> deleteAllFilesAndDirectories(FileOperations
 
 				@Override
 				public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
-					LOGGER.trace(() -> "preVisitDirectory: " + dir);
+					logger.trace(() -> "preVisitDirectory: " + dir);
 					if (isLinkWithTargetOutsideTempDir(dir)) {
 						warnAboutLinkWithTargetOutsideTempDir("link", dir);
 						delete(dir);
@@ -397,7 +397,7 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) th
 
 				@Override
 				public FileVisitResult visitFileFailed(Path file, IOException exc) {
-					LOGGER.trace(exc, () -> "visitFileFailed: " + file);
+					logger.trace(exc, () -> "visitFileFailed: " + file);
 					if (exc instanceof NoSuchFileException && !Files.exists(file, LinkOption.NOFOLLOW_LINKS)) {
 						return CONTINUE;
 					}
@@ -408,7 +408,7 @@ public FileVisitResult visitFileFailed(Path file, IOException exc) {
 
 				@Override
 				public FileVisitResult visitFile(Path file, BasicFileAttributes attributes) throws IOException {
-					LOGGER.trace(() -> "visitFile: " + file);
+					logger.trace(() -> "visitFile: " + file);
 					if (Files.isSymbolicLink(file) && isLinkWithTargetOutsideTempDir(file)) {
 						warnAboutLinkWithTargetOutsideTempDir("symbolic link", file);
 					}
@@ -418,7 +418,7 @@ public FileVisitResult visitFile(Path file, BasicFileAttributes attributes) thro
 
 				@Override
 				public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
-					LOGGER.trace(exc, () -> "postVisitDirectory: " + dir);
+					logger.trace(exc, () -> "postVisitDirectory: " + dir);
 					delete(dir);
 					return CONTINUE;
 				}
@@ -430,15 +430,15 @@ private boolean isLinkWithTargetOutsideTempDir(Path path) {
 						return !path.toRealPath().startsWith(rootRealPath);
 					}
 					catch (IOException e) {
-						LOGGER.trace(e,
+						logger.trace(e,
 							() -> "Failed to determine real path for " + path + "; assuming it is not a link");
 						return false;
 					}
 				}
 
 				private void warnAboutLinkWithTargetOutsideTempDir(String linkType, Path file) throws IOException {
 					Path realPath = file.toRealPath();
-					LOGGER.warn(() -> """
+					logger.warn(() -> """
 							Deleting %s from location inside of temp dir (%s) \
 							to location outside of temp dir (%s) but not the target file/directory""".formatted(
 						linkType, file, realPath));

junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/WorkerThreadPoolHierarchicalTestExecutorService.java

@@ -95,7 +95,7 @@ public final class WorkerThreadPoolHierarchicalTestExecutorService implements Hi
 		directly.
 	*/
 
-	private static final Logger LOGGER = LoggerFactory.getLogger(WorkerThreadPoolHierarchicalTestExecutorService.class);
+	private static final Logger logger = LoggerFactory.getLogger(WorkerThreadPoolHierarchicalTestExecutorService.class);
 
 	private final WorkQueue workQueue = new WorkQueue();
 	private final ExecutorService executor;
@@ -137,18 +137,18 @@ public final class WorkerThreadPoolHierarchicalTestExecutorService implements Hi
 		executor = new ThreadPoolExecutor(configuration.getCorePoolSize(), configuration.getMaxPoolSize(),
 			configuration.getKeepAliveSeconds(), SECONDS, new SynchronousQueue<>(), threadFactory,
 			rejectedExecutionHandler);
-		LOGGER.trace(() -> "initialized thread pool for parallelism of " + configuration.getParallelism());
+		logger.trace(() -> "initialized thread pool for parallelism of " + configuration.getParallelism());
 	}
 
 	@Override
 	public void close() {
-		LOGGER.trace(() -> "shutting down thread pool");
+		logger.trace(() -> "shutting down thread pool");
 		executor.shutdownNow();
 	}
 
 	@Override
 	public Future<@Nullable Void> submit(TestTask testTask) {
-		LOGGER.trace(() -> "submit: " + testTask);
+		logger.trace(() -> "submit: " + testTask);
 
 		var workerThread = WorkerThread.get();
 		if (workerThread == null) {
@@ -173,7 +173,7 @@ public void close() {
 	 */
 	@Override
 	public void invokeAll(List<? extends TestTask> testTasks) {
-		LOGGER.trace(() -> "invokeAll: " + testTasks);
+		logger.trace(() -> "invokeAll: " + testTasks);
 
 		var workerThread = WorkerThread.get();
 		Preconditions.condition(workerThread != null && workerThread.executor() == this,
@@ -219,13 +219,13 @@ private record RunLeaseAwareWorker(WorkerLease workerLease, BooleanSupplier pare
 
 		@Override
 		public void run() {
-			LOGGER.trace(() -> "starting worker");
+			logger.trace(() -> "starting worker");
 			try {
 				WorkerThread.getOrThrow().processQueueEntries(workerLease, parentDoneCondition);
 			}
 			finally {
 				workerLease.release(parentDoneCondition);
-				LOGGER.trace(() -> "stopping worker");
+				logger.trace(() -> "stopping worker");
 			}
 		}
 	}
@@ -286,11 +286,11 @@ void processQueueEntries(WorkerLease workerLease, BooleanSupplier doneCondition)
 			this.workerLease = workerLease;
 			while (!executor.isShutdown()) {
 				if (doneCondition.getAsBoolean()) {
-					LOGGER.trace(() -> "yielding resource lock");
+					logger.trace(() -> "yielding resource lock");
 					break;
 				}
 				if (workQueue.isEmpty()) {
-					LOGGER.trace(() -> "no queue entries available");
+					logger.trace(() -> "no queue entries available");
 					break;
 				}
 				processQueueEntries();
@@ -415,7 +415,7 @@ private WorkStealResult tryToStealWork(WorkQueue.Entry entry, BlockingMode block
 			}
 			var claimed = workQueue.remove(entry);
 			if (claimed) {
-				LOGGER.trace(() -> "stole work: " + entry.task);
+				logger.trace(() -> "stole work: " + entry.task);
 				var executed = executeStolenWork(entry, blockingMode);
 				if (executed) {
 					return WorkStealResult.EXECUTED_BY_THIS_WORKER;
@@ -439,7 +439,7 @@ private void waitFor(Map<WorkStealResult, List<WorkQueue.Entry>> queueEntriesByR
 				}
 				else {
 					runBlocking(future::isDone, () -> {
-						LOGGER.trace(() -> "blocking for forked children : %s".formatted(children));
+						logger.trace(() -> "blocking for forked children : %s".formatted(children));
 						return future.join();
 					});
 				}
@@ -457,7 +457,7 @@ private void executeAll(List<? extends TestTask> children) {
 			if (children.isEmpty()) {
 				return;
 			}
-			LOGGER.trace(() -> "running %d children directly".formatted(children.size()));
+			logger.trace(() -> "running %d children directly".formatted(children.size()));
 			if (children.size() == 1) {
 				executeTask(children.get(0));
 				return;
@@ -509,48 +509,48 @@ private void executeTask(TestTask testTask) {
 			if (!executed) {
 				var resourceLock = testTask.getResourceLock();
 				try (var ignored = runBlocking(() -> false, () -> {
-					LOGGER.trace(() -> "blocking for resource lock: " + resourceLock);
+					logger.trace(() -> "blocking for resource lock: " + resourceLock);
 					return resourceLock.acquire();
 				})) {
-					LOGGER.trace(() -> "acquired resource lock: " + resourceLock);
+					logger.trace(() -> "acquired resource lock: " + resourceLock);
 					doExecute(testTask);
 				}
 				catch (InterruptedException ex) {
 					Thread.currentThread().interrupt();
 				}
 				finally {
-					LOGGER.trace(() -> "released resource lock: " + resourceLock);
+					logger.trace(() -> "released resource lock: " + resourceLock);
 				}
 			}
 		}
 
 		private boolean tryExecuteTask(TestTask testTask) {
 			var resourceLock = testTask.getResourceLock();
 			if (resourceLock.tryAcquire()) {
-				LOGGER.trace(() -> "acquired resource lock: " + resourceLock);
+				logger.trace(() -> "acquired resource lock: " + resourceLock);
 				try (resourceLock) {
 					doExecute(testTask);
 					return true;
 				}
 				finally {
-					LOGGER.trace(() -> "released resource lock: " + resourceLock);
+					logger.trace(() -> "released resource lock: " + resourceLock);
 				}
 			}
 			else {
-				LOGGER.trace(() -> "failed to acquire resource lock: " + resourceLock);
+				logger.trace(() -> "failed to acquire resource lock: " + resourceLock);
 			}
 			return false;
 		}
 
 		private void doExecute(TestTask testTask) {
-			LOGGER.trace(() -> "executing: " + testTask);
+			logger.trace(() -> "executing: " + testTask);
 			stateStack.push(new State());
 			try {
 				testTask.execute();
 			}
 			finally {
 				stateStack.pop();
-				LOGGER.trace(() -> "finished executing: " + testTask);
+				logger.trace(() -> "finished executing: " + testTask);
 			}
 		}
 
@@ -650,7 +650,7 @@ private static class WorkStealingFuture extends BlockingAwareFuture<@Nullable Vo
 			if (entry.future.isDone()) {
 				return callable.call();
 			}
-			LOGGER.trace(() -> "blocking for child task: " + entry.task);
+			logger.trace(() -> "blocking for child task: " + entry.task);
 			return workerThread.runBlocking(entry.future::isDone, () -> {
 				try {
 					return callable.call();
@@ -673,7 +673,7 @@ private static class WorkQueue implements Iterable<WorkQueue.Entry> {
 
 		Entry add(TestTask task, int index) {
 			Entry entry = new Entry(task, index);
-			LOGGER.trace(() -> "forking: " + entry.task);
+			logger.trace(() -> "forking: " + entry.task);
 			return doAdd(entry);
 		}
 
@@ -682,7 +682,7 @@ void addAll(Collection<Entry> entries) {
 		}
 
 		void reAdd(Entry entry) {
-			LOGGER.trace(() -> "re-enqueuing: " + entry.task);
+			logger.trace(() -> "re-enqueuing: " + entry.task);
 			doAdd(entry);
 		}
 
@@ -726,10 +726,10 @@ private static final class Entry {
 				this.future = new CompletableFuture<>();
 				this.future.whenComplete((__, t) -> {
 					if (t == null) {
-						LOGGER.trace(() -> "completed normally: " + task);
+						logger.trace(() -> "completed normally: " + task);
 					}
 					else {
-						LOGGER.trace(t, () -> "completed exceptionally: " + task);
+						logger.trace(t, () -> "completed exceptionally: " + task);
 					}
 				});
 				this.task = task;
@@ -828,7 +828,7 @@ static class WorkerLeaseManager {
 		WorkerLease tryAcquire() {
 			boolean acquired = semaphore.tryAcquire();
 			if (acquired) {
-				LOGGER.trace(() -> "acquired worker lease for new worker (available: %d)".formatted(
+				logger.trace(() -> "acquired worker lease for new worker (available: %d)".formatted(
 					semaphore.availablePermits()));
 				return new WorkerLease(this::release);
 			}
@@ -837,7 +837,7 @@ WorkerLease tryAcquire() {
 
 		private ReacquisitionToken release(BooleanSupplier doneCondition) {
 			semaphore.release();
-			LOGGER.trace(() -> "release worker lease (available: %d)".formatted(semaphore.availablePermits()));
+			logger.trace(() -> "release worker lease (available: %d)".formatted(semaphore.availablePermits()));
 			compensation.accept(doneCondition);
 			return new ReacquisitionToken();
 		}
@@ -850,7 +850,7 @@ void reacquire() throws InterruptedException {
 				Preconditions.condition(!used, "Lease was already reacquired");
 				used = true;
 				semaphore.acquire();
-				LOGGER.trace(() -> "reacquired worker lease (available: %d)".formatted(semaphore.availablePermits()));
+				logger.trace(() -> "reacquired worker lease (available: %d)".formatted(semaphore.availablePermits()));
 			}
 		}