minor: promote test

[Young-Flash]

No description provided.

[peter-jerry-ye-code-review]

‼️ This code review is generated by a bot. Please verify the content before trusting it.

Here are some observations and potential issues from the provided git diff output:

1. Visibility Change:
   The visibility of the enum T[U] has been changed from pub to pub(all). This is a significant change because pub(all) makes the enum visible to the entire crate, whereas pub makes it visible to the parent module. If this change was intentional, ensure that it aligns with the design goals of the codebase. If not, it might expose internal implementation details unnecessarily.

2. Formatting Issue:
   The formatting of the enum variants (Empty and Node) is inconsistent. Typically, each variant should be on a new line for better readability. For example:

   pub(all) enum T[U] {
       Empty,
       Node(T[U], U, T[U], Int),
   }

   This improves readability and follows Rust's idiomatic style.

3. Missing Commas:
   The enum variants (Empty and Node) are missing trailing commas. While this is not a syntax error in Rust, adding commas is considered good practice as it makes the code more consistent and easier to modify in the future. For example:

   pub(all) enum T[U] {
       Empty,
       Node(T[U], U, T[U], Int),
   }

   This ensures uniformity and reduces the chance of errors when adding or removing variants.

Let me know if you need further clarification or assistance!