This line appears unnecessary. It was emitting the following warning:

    tests/test.rs:1:10: 1:18 warning: unknown `allow` attribute: `unstable`, #[warn(unknown_lints)] on by default
    tests/test.rs:1 #![allow(unstable)]

Author: drewcrawford

tests/test.rs

@@ -1,5 +1,3 @@
-#![allow(unstable)]
-
 #[macro_use]
 extern crate lazy_static;
 use std::collections::HashMap;