Move std::time unit tests to integration tests

1 files changed, 229 insertions, 0 deletions

diff --git a/library/std/tests/time.rs b/library/std/tests/time.rs
new file mode 100644
index 00000000000..40709eae37c
--- /dev/null
+++ b/library/std/tests/time.rs
@@ -0,0 +1,229 @@
+#![feature(duration_constants)]
+
+use std::fmt::Debug;
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
+
+macro_rules! assert_almost_eq {
+    ($a:expr, $b:expr) => {{
+        let (a, b) = ($a, $b);
+        if a != b {
+            let (a, b) = if a > b { (a, b) } else { (b, a) };
+            assert!(a - Duration::from_micros(1) <= b, "{:?} is not almost equal to {:?}", a, b);
+        }
+    }};
+}
+
+#[test]
+fn instant_monotonic() {
+    let a = Instant::now();
+    loop {
+        let b = Instant::now();
+        assert!(b >= a);
+        if b > a {
+            break;
+        }
+    }
+}
+
+#[test]
+#[cfg(not(target_arch = "wasm32"))]
+fn instant_monotonic_concurrent() -> std::thread::Result<()> {
+    let threads: Vec<_> = (0..8)
+        .map(|_| {
+            std::thread::spawn(|| {
+                let mut old = Instant::now();
+                let count = if cfg!(miri) { 1_000 } else { 5_000_000 };
+                for _ in 0..count {
+                    let new = Instant::now();
+                    assert!(new >= old);
+                    old = new;
+                }
+            })
+        })
+        .collect();
+    for t in threads {
+        t.join()?;
+    }
+    Ok(())
+}
+
+#[test]
+fn instant_elapsed() {
+    let a = Instant::now();
+    let _ = a.elapsed();
+}
+
+#[test]
+fn instant_math() {
+    let a = Instant::now();
+    let b = Instant::now();
+    println!("a: {a:?}");
+    println!("b: {b:?}");
+    let dur = b.duration_since(a);
+    println!("dur: {dur:?}");
+    assert_almost_eq!(b - dur, a);
+    assert_almost_eq!(a + dur, b);
+
+    let second = Duration::SECOND;
+    assert_almost_eq!(a - second + second, a);
+    assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a);
+
+    // checked_add_duration will not panic on overflow
+    let mut maybe_t = Some(Instant::now());
+    let max_duration = Duration::from_secs(u64::MAX);
+    // in case `Instant` can store `>= now + max_duration`.
+    for _ in 0..2 {
+        maybe_t = maybe_t.and_then(|t| t.checked_add(max_duration));
+    }
+    assert_eq!(maybe_t, None);
+
+    // checked_add_duration calculates the right time and will work for another year
+    let year = Duration::from_secs(60 * 60 * 24 * 365);
+    assert_eq!(a + year, a.checked_add(year).unwrap());
+}
+
+#[test]
+fn instant_math_is_associative() {
+    let now = Instant::now();
+    let offset = Duration::from_millis(5);
+    // Changing the order of instant math shouldn't change the results,
+    // especially when the expression reduces to X + identity.
+    assert_eq!((now + offset) - now, (now - now) + offset);
+
+    // On any platform, `Instant` should have the same resolution as `Duration` (e.g. 1 nanosecond)
+    // or better. Otherwise, math will be non-associative (see #91417).
+    let now = Instant::now();
+    let provided_offset = Duration::from_nanos(1);
+    let later = now + provided_offset;
+    let measured_offset = later - now;
+    assert_eq!(measured_offset, provided_offset);
+}
+
+#[test]
+fn instant_duration_since_saturates() {
+    let a = Instant::now();
+    assert_eq!((a - Duration::SECOND).duration_since(a), Duration::ZERO);
+}
+
+#[test]
+fn instant_checked_duration_since_nopanic() {
+    let now = Instant::now();
+    let earlier = now - Duration::SECOND;
+    let later = now + Duration::SECOND;
+    assert_eq!(earlier.checked_duration_since(now), None);
+    assert_eq!(later.checked_duration_since(now), Some(Duration::SECOND));
+    assert_eq!(now.checked_duration_since(now), Some(Duration::ZERO));
+}
+
+#[test]
+fn instant_saturating_duration_since_nopanic() {
+    let a = Instant::now();
+    #[allow(deprecated, deprecated_in_future)]
+    let ret = (a - Duration::SECOND).saturating_duration_since(a);
+    assert_eq!(ret, Duration::ZERO);
+}
+
+#[test]
+fn system_time_math() {
+    let a = SystemTime::now();
+    let b = SystemTime::now();
+    match b.duration_since(a) {
+        Ok(Duration::ZERO) => {
+            assert_almost_eq!(a, b);
+        }
+        Ok(dur) => {
+            assert!(b > a);
+            assert_almost_eq!(b - dur, a);
+            assert_almost_eq!(a + dur, b);
+        }
+        Err(dur) => {
+            let dur = dur.duration();
+            assert!(a > b);
+            assert_almost_eq!(b + dur, a);
+            assert_almost_eq!(a - dur, b);
+        }
+    }
+
+    let second = Duration::SECOND;
+    assert_almost_eq!(a.duration_since(a - second).unwrap(), second);
+    assert_almost_eq!(a.duration_since(a + second).unwrap_err().duration(), second);
+
+    assert_almost_eq!(a - second + second, a);
+    assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a);
+
+    let one_second_from_epoch = UNIX_EPOCH + Duration::SECOND;
+    let one_second_from_epoch2 =
+        UNIX_EPOCH + Duration::from_millis(500) + Duration::from_millis(500);
+    assert_eq!(one_second_from_epoch, one_second_from_epoch2);
+
+    // checked_add_duration will not panic on overflow
+    let mut maybe_t = Some(SystemTime::UNIX_EPOCH);
+    let max_duration = Duration::from_secs(u64::MAX);
+    // in case `SystemTime` can store `>= UNIX_EPOCH + max_duration`.
+    for _ in 0..2 {
+        maybe_t = maybe_t.and_then(|t| t.checked_add(max_duration));
+    }
+    assert_eq!(maybe_t, None);
+
+    // checked_add_duration calculates the right time and will work for another year
+    let year = Duration::from_secs(60 * 60 * 24 * 365);
+    assert_eq!(a + year, a.checked_add(year).unwrap());
+}
+
+#[test]
+fn system_time_elapsed() {
+    let a = SystemTime::now();
+    drop(a.elapsed());
+}
+
+#[test]
+fn since_epoch() {
+    let ts = SystemTime::now();
+    let a = ts.duration_since(UNIX_EPOCH + Duration::SECOND).unwrap();
+    let b = ts.duration_since(UNIX_EPOCH).unwrap();
+    assert!(b > a);
+    assert_eq!(b - a, Duration::SECOND);
+
+    let thirty_years = Duration::SECOND * 60 * 60 * 24 * 365 * 30;
+
+    // Right now for CI this test is run in an emulator, and apparently the
+    // aarch64 emulator's sense of time is that we're still living in the
+    // 70s. This is also true for riscv (also qemu)
+    //
+    // Otherwise let's assume that we're all running computers later than
+    // 2000.
+    if !cfg!(target_arch = "aarch64") && !cfg!(target_arch = "riscv64") {
+        assert!(a > thirty_years);
+    }
+
+    // let's assume that we're all running computers earlier than 2090.
+    // Should give us ~70 years to fix this!
+    let hundred_twenty_years = thirty_years * 4;
+    assert!(a < hundred_twenty_years);
+}
+
+#[test]
+fn big_math() {
+    // Check that the same result occurs when adding/subtracting each duration one at a time as when
+    // adding/subtracting them all at once.
+    #[track_caller]
+    fn check<T: Eq + Copy + Debug>(start: Option<T>, op: impl Fn(&T, Duration) -> Option<T>) {
+        const DURATIONS: [Duration; 2] =
+            [Duration::from_secs(i64::MAX as _), Duration::from_secs(50)];
+        if let Some(start) = start {
+            assert_eq!(
+                op(&start, DURATIONS.into_iter().sum()),
+                DURATIONS.into_iter().try_fold(start, |t, d| op(&t, d))
+            )
+        }
+    }
+
+    check(SystemTime::UNIX_EPOCH.checked_sub(Duration::from_secs(100)), SystemTime::checked_add);
+    check(SystemTime::UNIX_EPOCH.checked_add(Duration::from_secs(100)), SystemTime::checked_sub);
+
+    let instant = Instant::now();
+    check(instant.checked_sub(Duration::from_secs(100)), Instant::checked_add);
+    check(instant.checked_sub(Duration::from_secs(i64::MAX as _)), Instant::checked_add);
+    check(instant.checked_add(Duration::from_secs(100)), Instant::checked_sub);
+    check(instant.checked_add(Duration::from_secs(i64::MAX as _)), Instant::checked_sub);
+}