Convert Lines Of Characters Into A Vec Of Vecs In Rust

fn main() {
  let cases = vec![
    (
      "abcd\nefgh",
      vec![vec!['a', 'b', 'c', 'd'], vec!['e', 'f', 'g', 'h']]
    )
  ];

  cases.iter().for_each(|case| {
    let left = split_line_chars(case.0);
    dbg!(&left);
    assert_eq!(left, case.1);
  });

}

fn split_line_chars(source: &str) -> Vec<Vec<char>> {
  let lines = source.lines();
  lines.map(|line| line.chars().map(|c| c).collect()).collect()
}