Derive Clone for MiniCocoon (#32)

Solves the issue #29

src/mini.rs

@@ -21,6 +21,7 @@ use super::{
 pub const MINI_PREFIX_SIZE: usize = MiniFormatPrefix::SERIALIZE_SIZE;
 
 /// This is a mini cocoon for a convenient and cool encryption.
+#[derive(Clone)]
 pub struct MiniCocoon {
     key: Zeroizing<[u8; KEY_SIZE]>,
     rng: StdRng,
@@ -449,6 +450,20 @@ mod test {
         MiniCocoon::from_key(&[1; 32], &[0; 32]);
     }
 
+    #[test]
+    fn mini_cocoon_clone() {
+        let mut cocoon = MiniCocoon::from_password(b"password", &[0; 32]);
+        let cloned_cocoon = cocoon.clone();
+        const DATA: &'static [u8] = b"my-sercet-data";
+
+        // To check whether MiniCocoon gets cloned properly
+        let wrapped = cocoon.wrap(DATA).unwrap();
+        drop(cocoon);
+
+        let unwrapped = cloned_cocoon.unwrap(&wrapped).unwrap();
+        assert_eq!(&unwrapped, DATA);
+    }
+
     #[test]
     fn mini_cocoon_encrypt() {
         let mut cocoon = MiniCocoon::from_password(b"password", &[0; 32]);