message: Add test to check token.is_expired
diff: @@ -92,6 +92,7 @@ impl Token {
  Ok(())
  }
  + /// Check if the token is expired
  pub fn is_expired(&self) -> bool {
  self.expires_at
  .map_or(true, |x| Utc::now().timestamp() > x.timestamp())
  @@ -391,6 +392,8 @@ mod tests {
  use std::fs;
  use std::io::Read;
  + use std::thread::sleep;
  + use std::time::Duration;
  #[test]
  fn test_is_scope_subset() {
  @@ -427,6 +430,21 @@ mod tests {
  assert_eq!(tok_str, tok_str_file);
  }
  + #[test]
  + fn test_token_is_expired() {
  + let tok = TokenBuilder::default()
  + .access_token("test-access_token")
  + .expires_in(Duration::from_secs(1))
  + .expires_at(Utc::now())
  + .scope("playlist-read-private playlist-read-collaborative playlist-modify-public playlist-modify-private streaming ugc-image-upload user-follow-modify user-follow-read user-library-read user-library-modify user-read-private user-read-birthdate user-read-email user-top-read user-read-playback-state user-modify-playback-state user-read-currently-playing user-read-recently-played")
  + .refresh_token("...")
  + .build()
  + .unwrap();
  + assert!(!tok.is_expired());
  + sleep(Duration::from_secs(2));
  + assert!(tok.is_expired());
  + }
  +
  #[test]
  fn test_parse_response_code() {
  let spotify = SpotifyBuilder::default().build().unwrap();
  