Prevent snapshots from picking up old junk

If a previous run of the static site generator created new files, these
will be left lying around, even if subsequent runs wouldn't generate
that file anymore. This will lead to either a false negative or a false
positive.

- The file shouldn't be generated and isn't.
  Tests incorrectly fail because it's still there.

- The file should be generated but isn't.
  Tests incorrectly pass because it's still there.

Author: senekor

src/lib.rs

@@ -305,6 +305,7 @@ pub fn main() -> eyre::Result<()> {
 
 #[test]
 fn snapshot() {
+    std::fs::remove_dir_all(concat!(env!("CARGO_MANIFEST_DIR"), "/site")).unwrap();
     main().unwrap();
     let timestamped_files = ["releases.json", "feed.xml"];
     let inexplicably_non_deterministic_files = ["images/2023-08-rust-survey-2022/experiences.png"];