Hi David, congratulations on the release! I'm excited to play around with Hypothesis's bitstream-based shrinking. As you're aware, prop_flat_map is a pain to deal with, and I'd love to replace some of my proptest-based tests with Hegel.

I spent a little time looking at Hegel last week and it wasn't quite clear to me how I'd go about having something like a canonical generator for a type (similar to proptest's Arbitrary). I've found that to be very helpful while generating large structures to test something like serialization roundtripping against — in particular, the test-strategy library has derive macros that work very well for business logic types with, say, 10-15 enum variants each of which may have 0-10 subfields. I'm curious if that is supported today, or if you have plans to support this kind of composition in the future.

edit: oh I completely missed the macro to derive DefaultGenerator! Whoops

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tybug 3 hours ago | parent [-]

Yep, `#[derive(DefaultGenerator)]` and `generators::default<T>()` are the right tools here.

This is one of the areas we've dogfooded the least, so we'd definitely be happy to get feedback on any sharp corners here!

I think `from_type` is one of Hypothesis's most powerful and ergonomic strategies, and that while we probably can't get quite to that level in rust, we can still get something that's pretty great.

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DRMacIver 35 minutes ago | parent | next [-]

What do you think we're currently missing that Python's `from_type` has? I actually think the auto-deriving stuff we currently have in Rust is as good or better than from_type (e.g. it gets you the builder methods, has support for enums), but I've never been a heavy from_type user.

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sunshowers 2 hours ago | parent | prev [-]

Thank you! I have some particularly annoying proptest-based tests that I'll try porting over to Hegel soon. (Thanks for writing the Claude skill to do this.)

	▲	DRMacIver an hour ago \| parent [-]
		Please let us know how it goes! As Liam says, the derive generator is not very well dogfooded at present. The claude skill is a bit better, but we've only been through a few iterations of using it and getting Claude to improve it, and porting from proptest is one of the less well tested areas (because we don't use proptest much ourselves). I expect all of this works, but I'd like to know ways that it works less well than it could. Or, you know, to bask in the glow of praise of it working perfectly if that turns out to be an option.