Function missing_inline_tests 

pub fn missing_inline_tests(
    root: impl AsRef<Path>,
    exempt: &BTreeSet<String>,
) -> Result<Vec<PathBuf>>

Every Rust source file under root that defines testable behavior — a function with a body, outside any #[cfg(test)] module — but carries no inline #[cfg(test)] module, sorted. exempt holds the rule’s root-relative paths resolved from config.