Add tests for TryFrom<&Box> and ...&Vec> for Array (#212)

These have a `Clone` bound and otherwise act like the `TryFrom` impl
which converts from slices by cloning their contents

Author: tarcieri

tests/mod.rs

@@ -490,13 +490,30 @@ mod allocating {
         );
     }
 
+    #[test]
+    fn array_try_from_boxed_slice_ref() {
+        type A = Array<u8, U2>;
+        assert!(A::try_from(&vec![1].into_boxed_slice()).is_err());
+        assert_eq!(
+            &A::try_from(&vec![1, 2].into_boxed_slice()).unwrap(),
+            &[1, 2]
+        );
+    }
+
     #[test]
     fn array_try_from_vec() {
         type A = Array<u8, U2>;
         assert!(A::try_from(vec![1]).is_err());
         assert_eq!(&A::try_from(vec![1, 2]).unwrap(), &[1, 2]);
     }
 
+    #[test]
+    fn array_try_from_vec_ref() {
+        type A = Array<u8, U2>;
+        assert!(A::try_from(&vec![1]).is_err());
+        assert_eq!(&A::try_from(&vec![1, 2]).unwrap(), &[1, 2]);
+    }
+
     #[test]
     fn boxed_slice_from_array() {
         let array: Array<u8, U4> = Array([1, 2, 3, 4]);