add a better test

codex-rs/exec-server/tests/file_system/shared.rs

@@ -4,6 +4,8 @@ use codex_exec_server::CopyOptions;
 use codex_exec_server::CreateDirectoryOptions;
 use codex_exec_server::FILE_READ_CHUNK_SIZE;
 use codex_exec_server::FileMetadata;
+use codex_exec_server::FileSystemOperation;
+use codex_exec_server::FileSystemOperationOutput;
 use codex_exec_server::ReadDirectoryEntry;
 use codex_exec_server::RemoveOptions;
 use codex_protocol::models::AdditionalPermissionProfile;
@@ -196,6 +198,55 @@ async fn file_system_read_file_returns_bytes(
     Ok(())
 }
 
+#[test_case(FileSystemImplementation::Local ; "local")]
+#[test_case(FileSystemImplementation::Remote ; "remote")]
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn file_system_batch_preserves_operation_order(
+    implementation: FileSystemImplementation,
+) -> Result<()> {
+    let context = create_file_system_context(implementation).await?;
+    let file_system = context.file_system;
+
+    let tmp = TempDir::new()?;
+    let first_path = tmp.path().join("first.txt");
+    let second_path = tmp.path().join("second.txt");
+    std::fs::write(&first_path, "first")?;
+    std::fs::write(&second_path, "second")?;
+    let first_uri = PathUri::from_path(&first_path)?;
+    let second_uri = PathUri::from_path(&second_path)?;
+
+    let outputs = file_system
+        .execute_batch(
+            vec![
+                FileSystemOperation::ReadFile {
+                    path: first_uri.clone(),
+                },
+                FileSystemOperation::Canonicalize {
+                    path: second_uri.clone(),
+                },
+                FileSystemOperation::ReadFile { path: second_uri },
+            ],
+            /*sandbox*/ None,
+        )
+        .await
+        .with_context(|| format!("mode={implementation}"))?
+        .into_iter()
+        .collect::<std::io::Result<Vec<_>>>()?;
+
+    assert_eq!(
+        outputs,
+        vec![
+            FileSystemOperationOutput::ReadFile(b"first".to_vec()),
+            FileSystemOperationOutput::Canonicalize(PathUri::from_path(std::fs::canonicalize(
+                second_path
+            )?)?),
+            FileSystemOperationOutput::ReadFile(b"second".to_vec()),
+        ]
+    );
+
+    Ok(())
+}
+
 #[test_case(FileSystemImplementation::Local ; "local")]
 #[test_case(FileSystemImplementation::Remote ; "remote")]
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]