x86_64/usr/lib/rustlib/src/rust/library/core/tests/num/nan.rs

#[test]
fn test_nan() {
    let x = "NaN".to_string();
    assert_eq!(format!("{}", f64::NAN), x);
    assert_eq!(format!("{:e}", f64::NAN), x);
    assert_eq!(format!("{:E}", f64::NAN), x);
}