Quickcheck

Cargo.toml

@@ -14,7 +14,7 @@ build = "build.rs"
 exclude = ["/ci/*", "/.travis.yml", "/bors.toml"]
 
 [package.metadata.docs.rs]
-features = ["std", "bigint-std", "serde"]
+features = ["std", "bigint-std", "serde", "quickcheck"]
 
 [dependencies]
 
@@ -36,6 +36,11 @@ optional = true
 version = "1.0.0"
 default-features = false
 
+[dependencies.quickcheck]
+optional = true
+version = "0.9.0"
+default-features = false
+
 [features]
 default = ["bigint-std", "std"]
 i128 = ["num-integer/i128", "num-traits/i128"]

ci/test_full.sh

@@ -5,9 +5,12 @@ set -ex
 echo Testing num-rational on rustc ${TRAVIS_RUST_VERSION}
 
 FEATURES="std bigint-std serde"
-if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.26.0)$ ]]; then
+if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.26.0|1.31.0)$ ]]; then
   FEATURES="$FEATURES i128"
 fi
+if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable)$ ]]; then
+  FEATURES="$FEATURES quickcheck"
+fi
 
 # num-rational should build and test everywhere.
 cargo build --verbose

src/lib.rs

@@ -19,6 +19,8 @@
 
 #[cfg(feature = "bigint")]
 extern crate num_bigint as bigint;
+#[cfg(feature = "quickcheck")]
+extern crate quickcheck;
 #[cfg(feature = "serde")]
 extern crate serde;
 
@@ -47,6 +49,9 @@ use traits::{
     Pow, Signed, Zero,
 };
 
+#[cfg(feature = "quickcheck")]
+use quickcheck::{Arbitrary, Gen};
+
 /// Represents the ratio between two numbers.
 #[derive(Copy, Clone, Debug)]
 #[allow(missing_docs)]
@@ -254,6 +259,28 @@ impl<T: Clone + Integer> Ratio<T> {
     }
 }
 
+#[cfg(feature = "quickcheck")]
+impl<T: Arbitrary + Integer> Arbitrary for Ratio<T> {
+    fn arbitrary<G: Gen>(g: &mut G) -> Ratio<T> {
+        let mut denom = T::arbitrary(g);
+        while denom.is_zero() {
+            denom = T::arbitrary(g);
+        }
+        Ratio::new(T::arbitrary(g), denom)
+    }
+
+    #[cfg(feature = "std")]
+    fn shrink(&self) -> std::boxed::Box<Iterator<Item = Ratio<T>>> {
+        let numer = self.numer.shrink().next().unwrap_or(T::zero());
+        let denom = if self.denom.is_one() {
+            self.denom.clone()
+        } else {
+            self.denom.shrink().next().unwrap_or(T::one())
+        };
+        std::boxed::Box::new(std::iter::once(Ratio::new(numer, denom)))
+    }
+}
+
 impl<T: Clone + Integer + Pow<u32, Output = T>> Ratio<T> {
     /// Raises the `Ratio` to the power of an exponent.
     #[inline]