Allow alternative backends to provide observability metadata

[Zac-HD]

@pschanely you can put whatever (json-encodable) stuff in here that you might want 😁

@hgoldstein95 fyi, you might be interested in pschanely/hypothesis-crosshair#22 too.

[tybug]

Awesome! This is also immediately useful for debugging my local atheris provider. ¹

Footnotes

1. (though what I really want there is per-test-function observability, not per-test-case, since I'm running potentially millions of inputs and only want to report aggregate statistics. I realize this is outside standard hypothesis scope!) ↩

[Zac-HD]

This is also immediately useful for debugging my local atheris provider. ... though what I really want there is per-test-function observability, not per-test-case, since I'm running potentially millions of inputs and only want to report aggregate statistics.

Oh, we can totally do that - we already have per-test-function output for statistics! I'll hook this up so that you can send as many "information messages" as you wish after each test case and/or when we're finished with the test function.

(@hgoldstein95 you'll probably just want Tyche to ignore non-string information messages?)

[tybug]

Perfect ❤️