changed refresh-course zip internals to match the previous implementation

Author: Heliozoa

tmc-langs/src/course_refresher.rs

@@ -310,14 +310,21 @@ fn execute_zip(
         // filter hidden
         {
             let entry = entry?;
+            let relative_path = entry.path().strip_prefix(&root_path).unwrap(); // safe
+
             if entry.path().is_file() {
-                let relative_path = entry.path().strip_prefix(&root_path).unwrap(); // safe
                 writer.start_file(
                     relative_path.to_string_lossy(),
                     zip::write::FileOptions::default(),
                 )?;
                 let bytes = file_util::read_file(entry.path())?;
                 writer.write_all(&bytes).map_err(LangsError::ZipWrite)?;
+            } else {
+                // java-langs expects directories to have their own entries
+                writer.start_file(
+                    relative_path.join("").to_string_lossy(), // java-langs expects directory entries to have a trailing slash
+                    zip::write::FileOptions::default(),
+                )?;
             }
         }
         writer.finish()?;
@@ -518,6 +525,16 @@ mod test {
                     .to_string_lossy()
             )
             .is_err()); // hidden files filtered
+        assert!(fz
+            .by_name(
+                &Path::new("part2")
+                    .join("ex2")
+                    .join("dir")
+                    .join("subdir")
+                    .join("")
+                    .to_string_lossy(),
+            )
+            .is_ok()); // directories have their own entries with trailing slashes
         let mut file = fz
             .by_name(
                 &Path::new("part2")