Update return type of testDeleteDirectoryOnIOException0

Changed the return type of testDeleteDirectoryOnIOException0 from Void to File and updated the return statement to return the test directory. This improves clarity and allows the caller to access the created directory.

Author: mercyblitz

microsphere-java-core/src/test/java/io/microsphere/io/FileUtilsTest.java

@@ -120,7 +120,7 @@ void testDeleteDirectoryOnIOException() throws Exception {
         assertTrue(executor.awaitTermination(5, SECONDS));
     }
 
-    Void testDeleteDirectoryOnIOException0() throws Exception {
+    File testDeleteDirectoryOnIOException0() throws Exception {
         File testDir = createRandomTempDirectory();
 
         ExecutorService fileCreationExecutor = newSingleThreadExecutor();
@@ -170,7 +170,7 @@ Void testDeleteDirectoryOnIOException0() throws Exception {
         assertFalse(creatingFile.get());
         assertFalse(deletingDirectory.get());
 
-        return null;
+        return testDir;
     }
 
     @Test