impl Arbitrary for IpAddr

This complements the existing impls for Ipv4Addr and Ipv6Addr.

src/lib.rs

@@ -47,7 +47,7 @@ use std::borrow::{Cow, ToOwned};
 use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque};
 use std::ffi::{CString, OsString};
 use std::hash::BuildHasher;
-use std::net::{Ipv4Addr, Ipv6Addr};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::ops::Bound;
 use std::path::PathBuf;
 use std::rc::Rc;
@@ -1140,6 +1140,20 @@ impl<'a> Arbitrary<'a> for Ipv6Addr {
     }
 }
 
+impl<'a> Arbitrary<'a> for IpAddr {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        if u.arbitrary()? {
+            u.arbitrary().map(IpAddr::V4)
+        } else {
+            u.arbitrary().map(IpAddr::V6)
+        }
+    }
+
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (4, Some(16))
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;