Deleting temporary directories created in tests on shutdown

* Deleting using a shutdown hook (other approaches didn't work)

main/commons-test/src/main/java/org/cryptomator/common/test/TempFilesRemovedOnShutdown.java

@@ -0,0 +1,73 @@
+package org.cryptomator.common.test;
+
+import static java.nio.file.Files.walkFileTree;
+import static java.util.Collections.synchronizedSet;
+
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class TempFilesRemovedOnShutdown {
+
+	private static final Logger LOG = LoggerFactory.getLogger(TempFilesRemovedOnShutdown.class);
+
+	private static final Set<Path> PATHS_TO_REMOVE_ON_SHUTDOWN = synchronizedSet(new HashSet<>());
+	private static final Thread ON_SHUTDOWN_DELETER = new Thread(TempFilesRemovedOnShutdown::removeAll);
+
+	static {
+		Runtime.getRuntime().addShutdownHook(ON_SHUTDOWN_DELETER);
+	}
+
+	public static Path createTempDirectory(String prefix) throws IOException {
+		Path path = Files.createTempDirectory(prefix);
+		PATHS_TO_REMOVE_ON_SHUTDOWN.add(path);
+		return path;
+	}
+
+	private static void removeAll() {
+		PATHS_TO_REMOVE_ON_SHUTDOWN.forEach(TempFilesRemovedOnShutdown::remove);
+	}
+
+	private static void remove(Path path) {
+		try {
+			tryRemove(path);
+		} catch (Throwable e) {
+			LOG.debug("Failed to remove " + path, e);
+		}
+	}
+
+	private static void tryRemove(Path path) throws IOException {
+		walkFileTree(path, new FileVisitor<Path>() {
+			@Override
+			public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
+				return FileVisitResult.CONTINUE;
+			}
+
+			@Override
+			public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+				Files.delete(file);
+				return FileVisitResult.CONTINUE;
+			}
+
+			@Override
+			public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
+				return FileVisitResult.CONTINUE;
+			}
+
+			@Override
+			public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+				Files.delete(dir);
+				return FileVisitResult.CONTINUE;
+			}
+		});
+	}
+
+}

main/filesystem-invariants-tests/src/test/java/org/cryptomator/filesystem/invariants/FileSystemFactories.java

@@ -1,6 +1,6 @@
 package org.cryptomator.filesystem.invariants;
 
-import static java.nio.file.Files.createTempDirectory;
+import static org.cryptomator.common.test.TempFilesRemovedOnShutdown.createTempDirectory;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;

main/filesystem-nio/src/test/java/org/cryptomator/filesystem/nio/integrationtests/FilesystemSetupUtils.java

@@ -1,5 +1,7 @@
 package org.cryptomator.filesystem.nio.integrationtests;
 
+import static org.cryptomator.common.test.TempFilesRemovedOnShutdown.createTempDirectory;
+
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.UncheckedIOException;
@@ -15,7 +17,7 @@ class FilesystemSetupUtils {
 
 	public static Path emptyFilesystem() {
 		try {
-			return Files.createTempDirectory("test-filesystem");
+			return createTempDirectory("test-filesystem");
 		} catch (IOException e) {
 			throw new UncheckedIOException(e);
 		}
@@ -23,7 +25,7 @@ class FilesystemSetupUtils {
 
 	public static Path testFilesystem(Entry firstEntry, Entry... entries) {
 		try {
-			Path root = Files.createTempDirectory("test-filesystem");
+			Path root = createTempDirectory("test-filesystem");
 			firstEntry.create(root);
 			for (Entry entry : entries) {
 				entry.create(root);