rust/compiler/rustc_feature/src/tests.rs

use super::UnstableFeatures;

#[test]
fn rustc_bootstrap_parsing() {
    let is_bootstrap = |env, krate| {
        std::env::set_var("RUSTC_BOOTSTRAP", env);
        matches!(UnstableFeatures::from_environment(krate), UnstableFeatures::Cheat)
    };
    assert!(is_bootstrap("1", None));
    assert!(is_bootstrap("1", Some("x")));
    // RUSTC_BOOTSTRAP allows specifying a specific crate
    assert!(is_bootstrap("x", Some("x")));
    // RUSTC_BOOTSTRAP allows multiple comma-delimited crates
    assert!(is_bootstrap("x,y,z", Some("x")));
    assert!(is_bootstrap("x,y,z", Some("y")));
    // Crate that aren't specified do not get unstable features
    assert!(!is_bootstrap("x", Some("a")));
    assert!(!is_bootstrap("x,y,z", Some("a")));
    assert!(!is_bootstrap("x,y,z", None));

    // `RUSTC_BOOTSTRAP=0` is not recognized.
    assert!(!is_bootstrap("0", None));

    // `RUSTC_BOOTSTRAP=-1` is force-stable, no unstable features allowed.
    let is_force_stable = |krate| {
        std::env::set_var("RUSTC_BOOTSTRAP", "-1");
        matches!(UnstableFeatures::from_environment(krate), UnstableFeatures::Disallow)
    };
    assert!(is_force_stable(None));
    // Does not support specifying any crate.
    assert!(is_force_stable(Some("x")));
    assert!(is_force_stable(Some("x,y,z")));
}