add quickcheck arbitrary and some quickcheck tests

Cargo.toml

@@ -13,7 +13,7 @@ readme = "README.md"
 build = "build.rs"
 
 [package.metadata.docs.rs]
-features = ["std", "serde", "rand"]
+features = ["std", "serde", "rand", "quickcheck"]
 
 [[bench]]
 name = "bigint"
@@ -53,6 +53,16 @@ version = "1.0"
 default-features = false
 features = ["std"]
 
+[dependencies.quickcheck]
+optional = true
+version = "0.8"
+default-features = false
+
+[dependencies.quickcheck_macros]
+optional = true
+version = "0.8"
+default-features = false
+
 [dev-dependencies.serde_test]
 version = "1.0"
 

ci/test_full.sh

@@ -5,12 +5,15 @@ set -ex
 echo Testing num-bigint on rustc ${TRAVIS_RUST_VERSION}
 
 FEATURES="serde"
-if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.26.0|1.22.0)$ ]]; then
+if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.31.0|1.26.0|1.22.0)$ ]]; then
   FEATURES="$FEATURES rand"
 fi
-if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.26.0)$ ]]; then
+if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.31.0|1.26.0)$ ]]; then
   FEATURES="$FEATURES i128"
 fi
+if [[ "$TRAVIS_RUST_VERSION" =~ ^(nightly|beta|stable|1.31.0)$ ]]; then
+  FEATURES="$FEATURES quickcheck quickcheck_macros"
+fi
 
 # num-bigint should build and test everywhere.
 cargo build --verbose

src/bigint.rs

@@ -34,6 +34,9 @@ use biguint::{BigUint, IntDigits};
 use IsizePromotion;
 use UsizePromotion;
 
+#[cfg(feature = "quickcheck")]
+use quickcheck::{Arbitrary, Gen};
+
 /// A Sign is a `BigInt`'s composing element.
 #[derive(PartialEq, PartialOrd, Eq, Ord, Copy, Clone, Debug, Hash)]
 pub enum Sign {
@@ -114,6 +117,21 @@ pub struct BigInt {
     data: BigUint,
 }
 
+#[cfg(feature = "quickcheck")]
+impl Arbitrary for BigInt {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        let positive = bool::arbitrary(g);
+        let sign = if positive { Sign::Plus } else { Sign::Minus };
+        Self::from_biguint(sign, BigUint::arbitrary(g))
+    }
+
+    fn shrink(&self) -> Box<Iterator<Item = Self>> {
+        let sign = self.sign();
+        let unsigned_shrink = self.data.shrink();
+        Box::new(unsigned_shrink.map(move |x| BigInt::from_biguint(sign, x)))
+    }
+}
+
 /// Return the magnitude of a `BigInt`.
 ///
 /// This is in a private module, pseudo pub(crate)

src/biguint.rs

@@ -41,12 +41,28 @@ use UsizePromotion;
 
 use ParseBigIntError;
 
+#[cfg(feature = "quickcheck")]
+use quickcheck::{Arbitrary, Gen};
+
 /// A big unsigned integer type.
 #[derive(Clone, Debug, Hash)]
 pub struct BigUint {
     data: Vec<BigDigit>,
 }
 
+#[cfg(feature = "quickcheck")]
+impl Arbitrary for BigUint {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        // Use arbitrary from Vec
+        Self::new(Vec::<u32>::arbitrary(g))
+    }
+
+    fn shrink(&self) -> Box<Iterator<Item = Self>> {
+        // Use shrinker from Vec
+        Box::new(self.data.shrink().map(|x| BigUint::new(x)))
+    }
+}
+
 impl PartialEq for BigUint {
     #[inline]
     fn eq(&self, other: &BigUint) -> bool {

src/lib.rs

@@ -87,6 +87,8 @@ extern crate serde;
 
 extern crate num_integer as integer;
 extern crate num_traits as traits;
+#[cfg(feature = "quickcheck")]
+extern crate quickcheck;
 
 use std::error::Error;
 use std::fmt;