feat(ext4): file create, write, and delete with extent management

crates/servers/storage-server/src/tests/ext4.rs

@@ -368,6 +368,51 @@ fn list_dir_after_add() {
     assert_eq!(count, 2);
 }
 
+#[test]
+fn create_file_and_read_back() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    let h = fs.create(b"newfile").unwrap();
+    assert_eq!(fs.file_size(h), Some(0));
+    fs.close(h);
+    let mut entries = [DirEntry::empty(); 8];
+    let count = fs.list_dir(b"/", &mut entries).unwrap();
+    assert_eq!(count, 2);
+}
+
+#[test]
+fn write_and_read_back() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    let h = fs.create(b"writable").unwrap();
+    let written = fs.write(h, b"Hello, world!").unwrap();
+    assert_eq!(written, 13);
+    fs.close(h);
+    let h = fs.open(b"writable").unwrap();
+    let mut buf = [0u8; 32];
+    let n = fs.read(h, &mut buf).unwrap();
+    assert_eq!(n, 13);
+    assert_eq!(&buf[..13], b"Hello, world!");
+    fs.close(h);
+}
+
+#[test]
+fn delete_file_frees_resources() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    let h = fs.create(b"temp").unwrap();
+    fs.write(h, b"data").unwrap();
+    fs.close(h);
+    assert!(fs.delete(b"temp"));
+    assert!(fs.open(b"temp").is_none());
+    let h2 = fs.create(b"reuse").unwrap();
+    assert!(h2.raw() >= 0);
+    fs.close(h2);
+}
+
+#[test]
+fn create_with_missing_parent_fails() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    assert!(fs.create(b"nodir/file.txt").is_none());
+}
+
 #[test]
 fn read_past_eof_returns_zero() {
     let mut fs = Ext4::mount(format_ext4_disk()).unwrap();