add rust release channels

.travis.yml

@@ -1,9 +1,14 @@
 language: rust
 sudo: false
+rust:
+  - stable
+  - beta
+  - nightly
+
 matrix:
-  include:
-    - rust: 1.32.0
-    - rust: stable
+  allow_failures:
+    - rust: nightly
+
 branches:
   only:
     - master

src/lib.rs

@@ -112,7 +112,7 @@ mod tests {
         let extended_mac = super::WolPacket::extend_mac(&mac);
 
         assert_eq!(extended_mac.len(), super::MAC_PER_MAGIC * super::MAC_SIZE);
-        assert_eq!(&extended_mac[90..], &mac[..]);
+        assert_eq!(&extended_mac[(super::MAC_PER_MAGIC - 1) * super::MAC_SIZE..], &mac[..]);
     }
 
     #[test]