add test for time with isolation

Author: pvdrz

tests/pass/shims/time-with-isolation.rs

@@ -0,0 +1,35 @@
+//@compile-flags: -Zmiri-disable-isolation
+
+use std::time::{Duration, Instant};
+
+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);
+}
+
+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 `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);
+
+    test_sleep();
+}
+