Arbitrary 04x

Cargo.toml

@@ -37,6 +37,7 @@ pure-rust-locales = { version = "0.5.2", optional = true }
 criterion = { version = "0.4.0", optional = true }
 rkyv = {version = "0.7", optional = true}
 iana-time-zone = { version = "0.1.44", optional = true, features = ["fallback"] }
+arbitrary = { version = "1.0.0", features = ["derive"], optional = true }
 
 [target.'cfg(all(target_arch = "wasm32", not(any(target_os = "emscripten", target_os = "wasi"))))'.dependencies]
 wasm-bindgen = { version = "0.2", optional = true }

src/date.rs

@@ -545,6 +545,21 @@ where
     }
 }
 
+// Note that implementation of Arbitrary cannot be automatically derived for Date<Tz>, due to
+// the nontrivial bound <Tz as TimeZone>::Offset: Arbitrary.
+#[cfg(feature = "arbitrary")]
+impl<'a, Tz> arbitrary::Arbitrary<'a> for Date<Tz>
+where
+    Tz: TimeZone,
+    <Tz as TimeZone>::Offset: arbitrary::Arbitrary<'a>,
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Date<Tz>> {
+        let date = NaiveDate::arbitrary(u)?;
+        let offset = <Tz as TimeZone>::Offset::arbitrary(u)?;
+        Ok(Date::from_utc(date, offset))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::Date;

src/datetime/mod.rs

@@ -1150,6 +1150,21 @@ impl From<DateTime<Utc>> for js_sys::Date {
     }
 }
 
+// Note that implementation of Arbitrary cannot be simply derived for DateTime<Tz>, due to
+// the nontrivial bound <Tz as TimeZone>::Offset: Arbitrary.
+#[cfg(feature = "arbitrary")]
+impl<'a, Tz> arbitrary::Arbitrary<'a> for DateTime<Tz>
+where
+    Tz: TimeZone,
+    <Tz as TimeZone>::Offset: arbitrary::Arbitrary<'a>,
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<DateTime<Tz>> {
+        let datetime = NaiveDateTime::arbitrary(u)?;
+        let offset = <Tz as TimeZone>::Offset::arbitrary(u)?;
+        Ok(DateTime::from_utc(datetime, offset))
+    }
+}
+
 #[test]
 fn test_add_sub_months() {
     let utc_dt = Utc.ymd_opt(2018, 9, 5).unwrap().and_hms_opt(23, 58, 0).unwrap();

src/month.rs

@@ -30,6 +30,7 @@ use rkyv::{Archive, Deserialize, Serialize};
 #[derive(PartialEq, Eq, Copy, Clone, Debug, Hash)]
 #[cfg_attr(feature = "rustc-serialize", derive(RustcEncodable, RustcDecodable))]
 #[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Month {
     /// January
     January = 0,
@@ -191,6 +192,7 @@ impl num_traits::FromPrimitive for Month {
 
 /// A duration in calendar months
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Months(pub(crate) u32);
 
 impl Months {

src/naive/date.rs

@@ -193,6 +193,16 @@ pub const MIN_DATE: NaiveDate = NaiveDate::MIN;
 #[deprecated(since = "0.4.20", note = "Use NaiveDate::MAX instead")]
 pub const MAX_DATE: NaiveDate = NaiveDate::MAX;
 
+#[cfg(feature = "arbitrary")]
+impl arbitrary::Arbitrary<'_> for NaiveDate {
+    fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<NaiveDate> {
+        let year = u.int_in_range(MIN_YEAR..=MAX_YEAR)?;
+        let max_days = YearFlags::from_year(year).ndays();
+        let ord = u.int_in_range(1..=max_days)?;
+        NaiveDate::from_yo_opt(year, ord).ok_or(arbitrary::Error::IncorrectFormat)
+    }
+}
+
 // as it is hard to verify year flags in `NaiveDate::MIN` and `NaiveDate::MAX`,
 // we use a separate run-time test.
 #[test]

src/naive/datetime/mod.rs

@@ -79,6 +79,7 @@ pub const MAX_DATETIME: NaiveDateTime = NaiveDateTime::MAX;
 /// ```
 #[derive(PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
 #[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct NaiveDateTime {
     date: NaiveDate,
     time: NaiveTime,

src/naive/time/mod.rs

@@ -194,6 +194,17 @@ pub struct NaiveTime {
     frac: u32,
 }
 
+#[cfg(feature = "arbitrary")]
+impl arbitrary::Arbitrary<'_> for NaiveTime {
+    fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<NaiveTime> {
+        let secs = u.int_in_range(0..=86_399)?;
+        let nano = u.int_in_range(0..=1_999_999_999)?;
+        let time = NaiveTime::from_num_seconds_from_midnight_opt(secs, nano)
+            .expect("Could not generate a valid chrono::NaiveTime. It looks like implementation of Arbitrary for NaiveTime is erroneous.");
+        Ok(time)
+    }
+}
+
 impl NaiveTime {
     /// Makes a new `NaiveTime` from hour, minute and second.
     ///

src/offset/fixed.rs

@@ -152,6 +152,16 @@ impl fmt::Display for FixedOffset {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+impl arbitrary::Arbitrary<'_> for FixedOffset {
+    fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<FixedOffset> {
+        let secs = u.int_in_range(-86_399..=86_399)?;
+        let fixed_offset = FixedOffset::east_opt(secs)
+            .expect("Could not generate a valid chrono::FixedOffset. It looks like implementation of Arbitrary for FixedOffset is erroneous.");
+        Ok(fixed_offset)
+    }
+}
+
 // addition or subtraction of FixedOffset to/from Timelike values is the same as
 // adding or subtracting the offset's local_minus_utc value
 // but keep keeps the leap second information.

src/offset/local/mod.rs

@@ -52,6 +52,7 @@ mod tz_info;
 /// ```
 #[derive(Copy, Clone, Debug)]
 #[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Local;
 
 impl Local {

src/offset/utc.rs

@@ -41,6 +41,7 @@ use crate::{Date, DateTime};
 /// ```
 #[derive(Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Utc;
 
 #[cfg(feature = "clock")]

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};

src/weekday.rs

@@ -11,6 +11,7 @@ use rkyv::{Archive, Deserialize, Serialize};
 #[derive(PartialEq, Eq, Copy, Clone, Debug, Hash)]
 #[cfg_attr(feature = "rustc-serialize", derive(RustcEncodable, RustcDecodable))]
 #[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Weekday {
     /// Monday.
     Mon = 0,