message: Add tests for non-existing files
diff: @@ -23,4 +23,8 @@ fn main() {
  assert_eq!(bytes, contents.as_slice());
  // Removing file should succeed
  remove_file(path).unwrap();
  + // Opening non-existing file should fail
  + assert!(File::open(path).is_err());
  + // Removing non-existing file should fail
  + assert!(remove_file(path).is_err());
  }
  