From d9fce77427b6522eb300b0fbdcddbfa69cdece23 Mon Sep 17 00:00:00 2001
From: Kuba Marek <blue.cube@seznam.cz>
Date: Sat, 15 Oct 2022 23:41:31 +0200
Subject: [PATCH] Added implementation of `proptest::Arbitrary` (feature
 "proptest-support")

---
 CHANGELOG.md    |  1 +
 Cargo.toml      |  3 ++
 src/lib.rs      |  3 ++
 src/proptest.rs | 76 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 src/proptest.rs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 16ab630..8486321 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 ### Added
  - Added `TryFrom` fallible conversion.
+ - Added implementation of `proptest::Arbitrary` (feature "proptest-support").
 ### Changed
  - Made `new` a `const fn`
 ### Deprecated
diff --git a/Cargo.toml b/Cargo.toml
index 6c13844..1692642 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,6 +16,8 @@ categories = ["embedded", "no-std", "data-structures"]
 
 
 [dependencies]
+proptest = { version = "1", optional = true, default-features = false, features = ["std"] }
+
 
 [features]
 default = []
@@ -23,3 +25,4 @@ default = []
 # explicitly selected by a user. This crate works without explicit indication
 # both on std and no_std systems.
 std = []
+proptest-support = [ "proptest" ]
diff --git a/src/lib.rs b/src/lib.rs
index 59b4196..8e94e24 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -20,6 +20,9 @@ mod lib {
 
 mod conversion;
 
+#[cfg(feature = "proptest-support")]
+mod proptest;
+
 use lib::core::ops::{
     BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Not, Shl, ShlAssign, Shr,
     ShrAssign,
diff --git a/src/proptest.rs b/src/proptest.rs
new file mode 100644
index 0000000..2b89f9f
--- /dev/null
+++ b/src/proptest.rs
@@ -0,0 +1,76 @@
+//! Implementing `Arbitrary` trait from crate `proptest` for the u* and s* types.
+//! This allows them to be easily used as inputs in `proptest` propery based tests.
+//!
+//! The arbitrary selection strategy is adapted using `proptest`'s range strategy,
+//! with range from minimum value to the maximum value.
+
+use crate::*;
+use ::proptest::arbitrary::Arbitrary;
+use ::proptest::strategy::{Strategy, BoxedStrategy};
+
+macro_rules! implement_arbitrary {
+    ([$($name:ident),+], $type:ident) => {$(implement_arbitrary!($name, $type);)+};
+    ($name:ident, $type:ident) => {
+        impl Arbitrary for $name {
+            type Parameters = ();
+            type Strategy = BoxedStrategy<Self>;
+
+            fn arbitrary_with(_args: ()) -> BoxedStrategy<Self> {
+                let range = $type::from(Self::MIN)..=$type::from(Self::MAX);
+                range.prop_map(
+                    |x| Self::try_from(x).expect(
+                        "Value should be in range due to the interval we're choosing from"
+                    )
+                ).boxed()
+            }
+        }
+    }
+}
+
+
+implement_arbitrary!([u1, u2, u3, u4, u5, u6, u7], u8);
+implement_arbitrary!([u9, u10, u11, u12, u13, u14, u15], u16);
+implement_arbitrary!(
+    [
+        u17, u18, u19, u20, u21, u22, u23, u24, u25, u26, u27, u28, u29, u30, u31
+    ],
+    u32
+);
+implement_arbitrary!(
+    [
+        u33, u34, u35, u36, u37, u38, u39, u40, u41, u42, u43, u44, u45, u46, u47,
+        u48, u49, u50, u51, u52, u53, u54, u55, u56, u57, u58, u59, u60, u61, u62,
+        u63
+    ],
+    u64
+);
+
+implement_arbitrary!([i2, i3, i4, i5, i6, i7], i8);
+implement_arbitrary!([i9, i10, i11, i12, i13, i14, i15], i16);
+implement_arbitrary!(
+    [
+        i17, i18, i19, i20, i21, i22, i23, i24, i25, i26, i27, i28, i29, i30, i31
+    ],
+    i32
+);
+implement_arbitrary!(
+    [
+        i33, i34, i35, i36, i37, i38, i39, i40, i41, i42, i43, i44, i45, i46, i47,
+        i48, i49, i50, i51, i52, i53, i54, i55, i56, i57, i58, i59, i60, i61, i62,
+        i63
+    ],
+    i64
+);
+// Arbitrary implementations for i1, u65-u127 and i65-i127 are intentionally missing,
+// because these are not supported for conversions.
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ::proptest::prelude::*;
+
+    proptest!{
+        #[test]
+        fn u7_doesnt_panic(_ in any::<u7>()) {}
+    }
+}