From 2eda0f1a616e0e1d2413012fc0d48aef31f90347 Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex@asayers.com>
Date: Tue, 4 May 2021 20:31:54 +0900
Subject: [PATCH] Optionally implement Arbitrary for Naive{Date,Time,DateTime}

---
 Cargo.toml                | 1 +
 src/naive/date.rs         | 9 +++++++++
 src/naive/datetime/mod.rs | 1 +
 src/naive/time/mod.rs     | 9 +++++++++
 4 files changed, 20 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index c823e23e..850bc2dc 100644
--- a/Cargo.toml
+++ b/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 }
diff --git a/src/naive/date.rs b/src/naive/date.rs
index ba89d608..603d9e5d 100644
--- a/src/naive/date.rs
+++ b/src/naive/date.rs
@@ -193,6 +193,15 @@ 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 ord = u.int_in_range(1..=366)?;
+        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]
diff --git a/src/naive/datetime/mod.rs b/src/naive/datetime/mod.rs
index b67c8733..f2cee59f 100644
--- a/src/naive/datetime/mod.rs
+++ b/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,
diff --git a/src/naive/time/mod.rs b/src/naive/time/mod.rs
index 44184f86..8fa1698e 100644
--- a/src/naive/time/mod.rs
+++ b/src/naive/time/mod.rs
@@ -194,6 +194,15 @@ 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_400)?;
+        let frac = u.int_in_range(0..=2_000_000_000)?;
+        Ok(NaiveTime { secs, frac })
+    }
+}
+
 impl NaiveTime {
     /// Makes a new `NaiveTime` from hour, minute and second.
     ///