Generate a test per file in a directory

Is it possible to generate a test-case per file in a directory? I'm working on an image generating program, and we have [test images](https://github.com/casey/degenerate/tree/master/images) and it would be convenient to be able to say something like:

```rust
#[test_resources("images/*")]
fn image_test(path: &Path) {
// image test code
}
```

This is possible with [test-generator](https://github.com/frehberg/test-generator/) but it's less actively maintained.

Start by locating the procedural macro entry point for the Rust test-case attribute; the issue does not name a repository file or test. Compare the requested `images/*` example with the referenced test-generator project. Done means supporting one generated test case per matching file while preserving the shown function signature and path behavior.

Written by the indexing model from the issue text.