Remove rustc_serialize test

Author: kyeah

tests/modules/oid.rs

@@ -98,21 +98,3 @@ fn increasing() {
     let oid2 = oid2_res.unwrap();
     assert!(oid1 < oid2);
 }
-
-#[derive(RustcEncodable,RustcDecodable,PartialEq,Debug)]
-struct StructWithObjectId {
-    id: ObjectId
-}
-
-#[test]
-fn use_in_rustc_serialize() {
-    let s = "541b1a00e8a23afa832b218e";
-    let s = StructWithObjectId {
-        id: ObjectId::with_string(s).unwrap()
-    };
-    let encoded = json::encode(&s).unwrap();
-    assert_eq!("{\"id\":\"541b1a00e8a23afa832b218e\"}", encoded);
-
-    let decoded: StructWithObjectId = json::decode(&encoded).unwrap();
-    assert_eq!(s, decoded);
-}