Don't create mutations for feature excluded code

[Azkellas]

I have a project that looks roughly like this:

src/
    - lib.rs
    - other_file.rs

where libs.rs contains

#[cfg(feature = "my_feature")]
mod other_file;

...

and other_file contains both logic and tests.

Curently cargo mutants --no-default-features generates mutants in other_file.rs that will not be compiled and not be tested. This means lost time testing nothing and investigating wrong misses.

I guess it's good practice the run cargo mutants with --all-features and it solves this issue but having feedback on mutations that were discarded (at compilation or ideally at generation) due to feature selection would be valuable imho.

You can find a concrete example in this crate: https://github.com/Azkellas/mesh_to_sdf/tree/main/mesh_to_sdf where point/impl_*.rs file are feature gated to avoid pulling dependencies.

[sourcefrog]

Thanks, yep, it does not really understand any cfg items at the moment, but I would like to add it. There is #50 about this. Maybe it's useful to consider features as an important special case, distinct from cfg on OS or platform attributes.

having feedback on mutations that were discarded (at compilation or ideally at generation) due to feature selection would be valuable imho.

Actually this is interesting and a bit different from just knowing not to traverse the mod statement if the feature is off. I'll have to think about that.