rust/tests/run-coverage/unused_mod.coverage

$DIR/auxiliary/unused_mod_helper.rs:
    1|      0|pub fn never_called_function() {
    2|      0|    println!("I am never called");
    3|      0|}

$DIR/unused_mod.rs:
    1|       |#[path = "auxiliary/unused_mod_helper.rs"]
    2|       |mod unused_module;
    3|       |
    4|      1|fn main() {
    5|      1|    println!("hello world!");
    6|      1|}