ju_tcs_rust_23_2/
lib.rs

1use std::fs;
2use std::path::Path;
3
4pub fn head(path: &Path, n: usize) -> Vec<String> {
5    read_file_lines(path).into_iter().take(n).collect()
6}
7
8pub fn tail(path: &Path, n: usize) -> Vec<String> {
9    let lines = read_file_lines(path);
10    if lines.len() <= n {
11        lines
12    } else {
13        let to_skip = lines.len() - n;
14        lines.into_iter().skip(to_skip).collect()
15    }
16}
17
18fn read_file_lines(path: &Path) -> Vec<String> {
19    fs::read_to_string(path)
20        .unwrap()
21        .lines()
22        .map(String::from)
23        .collect()
24}
25
26#[cfg(test)]
27mod tests {
28    use super::*;
29
30    #[test]
31    fn head_works_with_small_n() {
32        let lines = head(&Path::new("test_files/lines.txt"), 2);
33        assert_eq!(lines, vec!["a", "b"]);
34    }
35
36    #[test]
37    fn head_works_with_big_n() {
38        let lines = head(&Path::new("test_files/lines.txt"), 10);
39        assert_eq!(lines, vec!["a", "b", "", "c", "d", "e"]);
40    }
41
42    #[test]
43    fn tail_works_with_small_n() {
44        let lines = tail(&Path::new("test_files/lines.txt"), 2);
45        assert_eq!(lines, vec!["d", "e"]);
46    }
47
48    #[test]
49    fn tail_works_with_big_n() {
50        let lines = tail(&Path::new("test_files/lines.txt"), 10);
51        assert_eq!(lines, vec!["a", "b", "", "c", "d", "e"]);
52    }
53}
ju_tcs_rust_23_2/lib.rs

ju_tcs_rust_23_2/
lib.rs
