message: fixed failed test.
diff: @@ -49,12 +49,12 @@ async fn client_from_refresh_token(oauth: &SpotifyOAuth, refresh_token: &str) ->
  // followed artists, and then unfollow the artists.
  async fn do_things(spotify: Spotify) {
  let artists = vec![
  - "3RGLhK1IP9jnYFH4BRFJBS".to_owned(), // The Clash
  - "0yNLKJebCb8Aueb54LYya3".to_owned(), // New Order
  - "2jzc5TC5TVFLXQlBNiIUzE".to_owned(), // a-ha
  + "3RGLhK1IP9jnYFH4BRFJBS", // The Clash
  + "0yNLKJebCb8Aueb54LYya3", // New Order
  + "2jzc5TC5TVFLXQlBNiIUzE", // a-ha
  ];
  spotify
  - .user_follow_artists(&artists)
  + .user_follow_artists(artists.clone())
  .await
  .expect("couldn't follow artists");
  println!("Followed {} artists successfully.", artists.len());
  @@ -70,7 +70,7 @@ async fn do_things(spotify: Spotify) {
  );
  spotify
  - .user_unfollow_artists(&artists)
  + .user_unfollow_artists(artists.clone())
  .await
  .expect("couldn't unfollow artists");
  println!("Unfollowed {} artists successfully.", artists.len());
  