message: test cargo clean with --release option
diff: @@ -117,6 +117,9 @@ fn clean_release() {
  [FINISHED] release [optimized] target(s) in [..]
  ",
  ).run();
  +
  + p.cargo("clean").arg("--release").run();
  + assert!(!p.build_dir().join("release").is_dir());
  }
  #[test]
  