You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test.rs
    path of file: ./repos/floem/editor-core/src/buffer
    
    the code of the file until where you have to start completion: use super::{Buffer, RopeText};

mod editing {
    use lapce_xi_rope::Rope;

    use super::*;
    use crate::{editor::EditType, selection::Selection};

    #[test]
    fn is_pristine() {
        let mut buffer = Buffer::new("");
   
    
        fn non_insertion_mode() {
            // To save some keystrokes.
            fn v(buf: &Buffer, off: usize, n: usize, end: usize) {
                assert_eq!(buf.move_n_wordends_forward(off, n, false), end);
            }

            let buffer = Buffer::new("one two three  four  ");
            //                      ->012345678901234567890<-

            // 0 count does not move.
            v(&buffer, 0, 0, 0);

            for offset in 0..2 {
                v(&buffer, offset, 1, 2);
                v(&buffer, offset, 2, 6);
                v(&buffer, offset, 3, 12);
            }

            let end = buffer.len() - 1;
            // Trying to move beyond the buffer end.
            for offset in 0..end {
                v(&buffer, offset, 100, 21);
            }

            v(&buffer, 2, 1, 6);
            v(&buffer, 2, 2, 12);
            v(&buffer, 2, 3, 18);
            v(&buffer, 2, 10, 21);

            let buffer = Buffer::new("one\n\ntwo\n\n\nthree\n\n\n");
            //                      ->0123 4 5678 9 0 123456 7 8 <-

            v(&buffer, 0, 2, 7);
            v(&buffer, 0, 3, 15);
            v(&buffer, 0, 4, 19);
        }