When adding an import based on a completion to a unit test it becomes an unused import in the normal build

The problem is that if you have some code like

#[test]
fn test_all_room_ids_different() {
  let mut set = HashS
}

and then you press Ctrl+Space at the end of the line and pick std::collections::HashSet as the completion, it'll add the std::collections::HashSet to the top of the entire module. Except if nothing else in the module is using a HashSet then the non-test build now marks the import as an unused import.

I don't know what the good answer is here, but there are two options that come to mind:

1. put the new import at the top of the test function
2. put the new import at the top of the module behind #[cfg(test)]

Reproduce the completion-import behavior in a Rust unit test where HashSet is used only inside #[test]. Then inspect the completion import insertion entry point and determine whether the import should be scoped to the test or guarded with #[cfg(test)]. Done means the normal build no longer reports the generated import as unused.