-#![cfg_attr(all(test, feature = "unstable"), feature(test))]
-#[cfg(all(test, feature = "unstable"))] extern crate test;
+#![cfg_attr(all(any(test, feature = "_test_utils"), feature = "unstable"), feature(test))]
+#[cfg(all(any(test, feature = "_test_utils"), feature = "unstable"))] extern crate test;