sry for my poor english.

I use command as follow to create this project

cargo new --lib lsp_rust_tests
cd lsp_rust_tests
mkdir -p tests

first

edit src/lib.rs file

pub fn add_2(num: i32) -> i32 {
    num + 2
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn it_works() {
        assert_eq!(2 + 2, 4);
    }

    #[test]
    fn add_2_test() {
        assert_eq!(4, add_2(2));
    }
}

autocomplete works in this file;

second

edit tests/add_test.rs

use lsp_rust_tests;
#[test]
fn test() {
    assert_eq!(4, lsp_rust_tests::add_2(2));
}

autocomplete in this file not work;

lsp-describe-session

when I create and edit some new file in src folder like src/utils.rs

if there is no mod utils in my lib.rs, autocomplete will not work at all.

after i add mod uitls, it works.