You've named it after bird cages? Is there some significance?

I'd add a NIP01, NIP02, etc. folder layer to the support folder, otherwise you're going to end up drowning in feature files.

Like I was saying before (maybe you're already doing this), it would be useful to find similar objects and group them and work with inheritance.

This goes back to the "generic reply note kind" debate, but it probably wouldn't only apply to that. Tags would be an obvious one, for instance.

Or simply the core structure of notes. Each test json should be a full example of a complete event json.

I always feel confused, reading through the specs, to see similar things written slightly differently, or only partly. The test should define the minimum viable version of each, once, and then add stuff to other versions. And then people would always see THE WHOLE JSON, when looking at the test.

Or something like that. I don't know. I suck at object-oriented design, but you probably don't.

This is a good example of how powerful this is.

https://github.com/schmijos/nostr-voliere/blob/main/features/01_filtering.feature

You got good at this, really fast, BTW. I'm used to writing these for website tests, so it's interesting to see them applied a layer down.