Function is_doc 

pub fn is_doc(name: &str) -> bool

True when name is the name of a doc test: it has a space, as in crates/x/src/lib.rs - ulid (line 57). The name of each other test is a Rust path.

use hygiene::part::is_doc;

assert!(is_doc("crates/x/src/lib.rs - ulid (line 57)"));
assert!(!is_doc("cli::help"));