Add impl Default for Cow (#32)

* Add impl Default for Cow

* Fix type inference on &[]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "beef"
-version = "0.4.3"
+version = "0.4.4"
 authors = ["Maciej Hirsz <hello@maciej.codes>"]
 edition = "2018"
 description = "More compact Cow"

src/generic.rs

@@ -288,6 +288,18 @@ where
     }
 }
 
+impl<'a, T, U> Default for Cow<'a, T, U>
+where
+    T: Beef + ?Sized,
+    U: Capacity,
+    &'a T: Default,
+{
+    #[inline]
+    fn default() -> Self {
+        Cow::borrowed(Default::default())
+    }
+}
+
 impl<T, U> Eq for Cow<'_, T, U>
 where
     T: Eq + Beef + ?Sized,

src/lib.rs

@@ -261,6 +261,20 @@ macro_rules! test { ($tmod:ident => $cow:path) => {
 
             assert_eq!(&*FOO, b"bar");
         }
+
+        #[test]
+        fn default_str() {
+            let empty: Cow<str> = Default::default();
+
+            assert_eq!(&*empty, "");
+        }
+
+        #[test]
+        fn default_slice() {
+            let empty: Cow<[u8]> = Default::default();
+
+            assert_eq!(&*empty, b"");
+        }
     }
 } }