rust/tests/run-pass/time.rs

// ignore-windows: TODO clock shims are not implemented on Windows
// compile-flags: -Zmiri-disable-isolation

use std::time::{SystemTime, Instant};

fn main() {
    let now1 = SystemTime::now();
    // Do some work to make time pass.
    for _ in 0..10 { drop(vec![42]); }
    let now2 = SystemTime::now();
    assert!(now2 > now1);
    let diff = now2.duration_since(now1).unwrap();
    assert!(diff.as_micros() > 0);
    assert_eq!(now1 + diff, now2);
    assert_eq!(now2 - diff, now1);

    let now1 = Instant::now();
    // Do some work to make time pass.
    for _ in 0..10 { drop(vec![42]); }
    let now2 = Instant::now();
    assert!(now2 > now1);

    #[cfg(target_os = "linux")] // TODO: macOS does not support Instant subtraction
    {
        let diff = now2.duration_since(now1);
        assert!(diff.as_micros() > 0);
        assert_eq!(now1 + diff, now2);
        assert_eq!(now2 - diff, now1);
    }
}