rust/tests/pass/time.rs

// compile-flags: -Zmiri-disable-isolation

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

fn duration_sanity(diff: Duration) {
    // On my laptop, I observed times around 15-40ms. Add 10x lee-way both ways.
    assert!(diff.as_millis() > 1);
    assert!(diff.as_millis() < 500);
}

// Sleeping on Windows is not supported yet.
#[cfg(unix)]
fn test_sleep() {
    let before = Instant::now();
    std::thread::sleep(Duration::from_millis(100));
    let after = Instant::now();
    assert!((after - before).as_millis() >= 100);
}

fn main() {
    // Check `SystemTime`.
    let now1 = SystemTime::now();
    let seconds_since_epoch = now1.duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
    let years_since_epoch = seconds_since_epoch / 3600 / 24 / 365;
    let year = 1970 + years_since_epoch;
    assert!(2020 <= year && year < 2100);
    // Do some work to make time pass.
    for _ in 0..10 { drop(vec![42]); }
    let now2 = SystemTime::now();
    assert!(now2 > now1);
    // Sanity-check the difference we got.
    let diff = now2.duration_since(now1).unwrap();
    assert_eq!(now1 + diff, now2);
    assert_eq!(now2 - diff, now1);
    duration_sanity(diff);

    // Check `Instant`.
    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);
    // Sanity-check the difference we got.
    let diff = now2.duration_since(now1);
    assert_eq!(now1 + diff, now2);
    assert_eq!(now2 - diff, now1);
    duration_sanity(diff);

    #[cfg(unix)]
    test_sleep();
}