Code coverage ignore comments

language design
1

Would like to see an option to add comments to exclude certain lines of code from code coverage like this...

println!("Loading...");

let response: ResponseType = match api_lib::get().await {
    Ok(response) => response,

    //coverage ignore start
    Err(err) => {
        eprintln!("{err}");
        std::process::exit(1);
    }
    //coverage ignore end
};

println!("Welcome...");

This will help get closer to 100% code coverage for those parts in your code where you do not expect to test such as weather a 3rd party API fails and weather the error is handled properly.

JavaScript's Vitest and PHP's PHPUnit has this feature in their own way.

2

imo Rust uses attributes for stuff like this rather than magic comments, e.g. the #[rustfmt::skip] attribute.

2 Likes
3

What do you currently use for code coverage?

If you use cargo-llvm-cov, the attribute is called coverage(off), like this:

cargo-tarpaulin also supports this attribute, and has its own attribute

This page talks more about the difference between those two tools

Anyway I'm not 100% sure but I think in both cases you apply to whole functions, not to sections of functions like this. I'm not sure if factoring this block into a function can help, either.

Anyway, since this doesn't require changes to Rust, I think further discussion should happen in https://users.rust-lang.org/

3 Likes