Impl Arbitrary for Naive{Date,Time,DateTime}

Cargo.toml

@@ -33,6 +33,7 @@ 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 }

ci/github.sh

@@ -6,7 +6,7 @@ set -euo pipefail
 source "${BASH_SOURCE[0]%/*}/_shlib.sh"
 
 TEST_TZS=(ACST-9:30 EST4 UTC0 Asia/Katmandu)
-FEATURES=(std serde clock "alloc serde" unstable-locales)
+FEATURES=(std serde clock "alloc serde" unstable-locales arbitrary)
 CHECK_FEATURES=(alloc "std unstable-locales" "serde clock" "clock unstable-locales")
 RUST_132_FEATURES=(serde)
 

src/naive/date.rs

@@ -2060,6 +2060,55 @@ mod serde {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+#[cfg_attr(docsrs, doc(cfg(feature = "arbitrary")))]
+mod arbitrary {
+    use super::{NaiveDate, YearFlags, MAX_YEAR, MIN_YEAR};
+    use arbitrary::{Arbitrary, Unstructured};
+
+    #[cfg(feature = "arbitrary")]
+    impl Arbitrary<'_> for NaiveDate {
+        fn arbitrary(u: &mut 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)?;
+            let date = NaiveDate::from_yo_opt(year, ord)
+                .expect("Could not generate a valid chrono::NaiveDate. It looks like implementation of Arbitrary for NaiveDate is erroneous.");
+            Ok(date)
+        }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        const UNSTRCUTURED_BINARY1: [u8; 8] = [0x8f, 0xc2, 0x95, 0xdc, 0x3e, 0x45, 0xb2, 0x3e];
+        const UNSTRCUTURED_BINARY2: [u8; 8] = [0x8b, 0xad, 0x2c, 0xc9, 0xf0, 0x05, 0x75, 0x84];
+
+        #[test]
+        fn test_different_unstructured() {
+            let mut unstrctured1 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+            let date1 = NaiveDate::arbitrary(&mut unstrctured1).unwrap();
+
+            let mut unstrctured2 = Unstructured::new(&UNSTRCUTURED_BINARY2);
+            let date2 = NaiveDate::arbitrary(&mut unstrctured2).unwrap();
+
+            assert_ne!(date1, date2);
+        }
+
+        #[test]
+        fn test_same_unstructured() {
+            let mut unstrctured1 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+            let date1 = NaiveDate::arbitrary(&mut unstrctured1).unwrap();
+
+            let mut unstrctured2 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+            let date2 = NaiveDate::arbitrary(&mut unstrctured2).unwrap();
+
+            assert_eq!(date1, date2);
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{

src/naive/datetime/mod.rs

@@ -74,6 +74,7 @@ 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/arbitrary.rs

@@ -0,0 +1,44 @@
+#![cfg_attr(docsrs, doc(cfg(feature = "arbitrary")))]
+
+use super::NaiveTime;
+use arbitrary::{Arbitrary, Unstructured};
+
+impl Arbitrary<'_> for NaiveTime {
+    fn arbitrary(u: &mut 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)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const UNSTRCUTURED_BINARY1: [u8; 8] = [0x8f, 0xc2, 0x95, 0xdc, 0x3e, 0x45, 0xb2, 0x3e];
+    const UNSTRCUTURED_BINARY2: [u8; 8] = [0x8b, 0xad, 0x2c, 0xc9, 0xf0, 0x05, 0x75, 0x84];
+
+    #[test]
+    fn test_different_unstructured() {
+        let mut unstrctured1 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+        let time1 = NaiveTime::arbitrary(&mut unstrctured1).unwrap();
+
+        let mut unstrctured2 = Unstructured::new(&UNSTRCUTURED_BINARY2);
+        let time2 = NaiveTime::arbitrary(&mut unstrctured2).unwrap();
+
+        assert_ne!(time1, time2);
+    }
+
+    #[test]
+    fn test_same_unstructured() {
+        let mut unstrctured1 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+        let time1 = NaiveTime::arbitrary(&mut unstrctured1).unwrap();
+
+        let mut unstrctured2 = Unstructured::new(&UNSTRCUTURED_BINARY1);
+        let time2 = NaiveTime::arbitrary(&mut unstrctured2).unwrap();
+
+        assert_eq!(time1, time2);
+    }
+}

src/naive/time/mod.rs

@@ -21,6 +21,9 @@ use crate::{TimeDelta, Timelike};
 #[cfg(feature = "serde")]
 mod serde;
 
+#[cfg(feature = "arbitrary")]
+mod arbitrary;
+
 #[cfg(test)]
 mod tests;