impl feature gated quickcheck arbitrary for hash

Cargo.toml

@@ -11,8 +11,10 @@ heapsize = { version = "0.4", optional = true }
 libc = { version = "0.2", optional = true, default-features = false }
 rand = { version = "0.4", optional = true }
 rustc-hex = { version = "1.0", optional = true }
+quickcheck = { version = "0.6", optional = true }
 
 [features]
 default = ["libc"]
 std = ["rustc-hex", "rand"]
 heapsizeof = ["heapsize"]
+impl_quickcheck_arbitrary = ["quickcheck"]

src/hash.rs

@@ -301,6 +301,7 @@ macro_rules! construct_hash {
 		impl_std_for_hash!($from, $size);
 		impl_heapsize_for_hash!($from);
 		impl_libc_for_hash!($from, $size);
+		impl_quickcheck_arbitrary_for_hash!($from, $size);
 	}
 }
 
@@ -463,3 +464,25 @@ macro_rules! impl_libc_for_hash {
 		}
 	}
 }
+
+#[cfg(feature="impl_quickcheck_arbitrary")]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! impl_quickcheck_arbitrary_for_hash {
+	($name: ty, $n_bytes: tt) => {
+		impl $crate::quickcheck::Arbitrary for $name {
+			fn arbitrary<G: $crate::quickcheck::Gen>(g: &mut G) -> Self {
+				let mut res = [0u8; $n_bytes];
+				g.fill_bytes(&mut res[..$n_bytes]);
+				res.as_ref().into()
+			}
+		}
+	}
+}
+
+#[cfg(not(feature="impl_quickcheck_arbitrary"))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! impl_quickcheck_arbitrary_for_hash {
+	($name: ty, $n_bytes: tt) => {}
+}

src/lib.rs

@@ -32,5 +32,9 @@ pub extern crate rustc_hex;
 #[doc(hidden)]
 pub extern crate rand;
 
+#[cfg(feature="impl_quickcheck_arbitrary")]
+#[doc(hidden)]
+pub extern crate quickcheck;
+
 mod hash;
 pub use hash::*;