Implement Arbitrary for Duration

src/oldtime.rs

@@ -482,6 +482,24 @@ fn div_rem_64(this: i64, other: i64) -> (i64, i64) {
     (this / other, this % other)
 }
 
+#[cfg(feature = "arbitrary")]
+impl arbitrary::Arbitrary<'_> for Duration {
+    fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<Duration> {
+        const MIN_SECS: i64 = i64::MIN / MILLIS_PER_SEC - 1;
+        const MAX_SECS: i64 = i64::MAX / MILLIS_PER_SEC;
+
+        let secs: i64 = u.int_in_range(MIN_SECS..=MAX_SECS)?;
+        let nanos: i32 = u.int_in_range(0..=(NANOS_PER_SEC - 1))?;
+        let duration = Duration { secs, nanos };
+
+        if duration < MIN || duration > MAX {
+            Err(arbitrary::Error::IncorrectFormat)
+        } else {
+            Ok(duration)
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{Duration, OutOfRangeError, MAX, MIN};