message: clean up secret_key_path.
diff: @@ -971,10 +971,9 @@ mod tests {
  // create secret key file in tempdir.
  let keys_dir = tempdir().expect("Failed to create temp dir.");
  let secret_key_path = keys_dir.path().join("key.pem");
  - let secret_key_path_clone = secret_key_path.clone();
  - let secret_key_path_str = secret_key_path_clone.to_str().unwrap();
  + let secret_key_path_str = secret_key_path.to_str().unwrap();
  let mut secret_key_file =
  - fs::File::create(secret_key_path).expect("Failed to create test secret key file.");
  + fs::File::create(&secret_key_path).expect("Failed to create test secret key file.");
  write!(secret_key_file, "{}", happy::PRIVATE_KEY)
  .expect("Failed to write data to test secret key file.");
  @@ -999,10 +998,9 @@ mod tests {
  // create secret key file in tempdir.
  let keys_dir = tempdir().expect("Failed to create temp dir.");
  let secret_key_path = keys_dir.path().join("key.pem");
  - let secret_key_path_clone = secret_key_path.clone();
  - let secret_key_path_str = secret_key_path_clone.to_str().unwrap();
  + let secret_key_path_str = secret_key_path.to_str().unwrap();
  let mut secret_key_file =
  - fs::File::create(secret_key_path).expect("Failed to create test secret key file.");
  + fs::File::create(&secret_key_path).expect("Failed to create test secret key file.");
  write!(secret_key_file, "{}", happy::PRIVATE_KEY)
  .expect("Failed to write data to test secret key file.");
  