Here is an example https://github.com/ianm199/nginx-rs-port/blob/main/crates/ng...

Basically I use these "kits" to prove that the behavior is working as expected with mocked data/ interfaces and then only after these kits pass I'll run the real test suite files as confirmation. So these let you iterate a lot faster than the official test suite because it is very slow.

These are bootstrapped from the real tests.

The other commenter was being a bit dismissive but this is the kind of thing I'm taking away as a real useful pattern to do verification of behavior at scale.