Add tests from Cow

Author: cuviper

src/liballoc/tests/borrow.rs

@@ -0,0 +1,47 @@
+use std::borrow::{Cow, ToOwned};
+use std::ffi::{CStr, OsStr};
+use std::path::Path;
+use std::rc::Rc;
+use std::sync::Arc;
+
+macro_rules! test_from_cow {
+    ($value:ident => $($ty:ty),+) => {$(
+        let borrowed = <$ty>::from(Cow::Borrowed($value));
+        let owned = <$ty>::from(Cow::Owned($value.to_owned()));
+        assert_eq!($value, &*borrowed);
+        assert_eq!($value, &*owned);
+    )+};
+    ($value:ident : & $ty:ty) => {
+        test_from_cow!($value => Box<$ty>, Rc<$ty>, Arc<$ty>);
+    }
+}
+
+#[test]
+fn test_from_cow_slice() {
+    let slice: &[i32] = &[1, 2, 3];
+    test_from_cow!(slice: &[i32]);
+}
+
+#[test]
+fn test_from_cow_str() {
+    let string = "hello";
+    test_from_cow!(string: &str);
+}
+
+#[test]
+fn test_from_cow_c_str() {
+    let string = CStr::from_bytes_with_nul(b"hello\0").unwrap();
+    test_from_cow!(string: &CStr);
+}
+
+#[test]
+fn test_from_cow_os_str() {
+    let string = OsStr::new("hello");
+    test_from_cow!(string: &OsStr);
+}
+
+#[test]
+fn test_from_cow_path() {
+    let path = Path::new("hello");
+    test_from_cow!(path: &Path);
+}

src/liballoc/tests/lib.rs

@@ -20,6 +20,7 @@ use std::hash::{Hash, Hasher};
 
 mod arc;
 mod binary_heap;
+mod borrow;
 mod boxed;
 mod btree;
 mod cow_str;