add NewServiceExt tests

src/service/map_err.rs

@@ -191,7 +191,7 @@ mod tests {
     use futures::future::{err, FutureResult};
 
     use super::*;
-    use service::{Service, ServiceExt};
+    use service::{IntoNewService, NewServiceExt, Service, ServiceExt};
 
     struct Srv;
 
@@ -225,4 +225,17 @@ mod tests {
         assert!(res.is_err());
         assert_eq!(res.err().unwrap(), "error");
     }
+
+    #[test]
+    fn test_new_service() {
+        let blank = || Ok::<_, ()>(Srv);
+        let new_srv = blank.into_new_service().map_err(|_| "error");
+        if let Async::Ready(mut srv) = new_srv.new_service().poll().unwrap() {
+            let res = srv.call(()).poll();
+            assert!(res.is_err());
+            assert_eq!(res.err().unwrap(), "error");
+        } else {
+            panic!()
+        }
+    }
 }