I think this is quite tricky to do without making a large special case for FromDataPoints as a ParameterSupplier within the Theories runner, which doesn't seem too great to me.

This behaviour also wouldn't match AllMembersSupplier, which looks for possible datapoints at test run time instead.  Tests will fail when run if no datapoints are eventually available then though (either because there are none, or none with the correct name, or none that satisfy the theory assumptions).

The case where an annotated datapoint array/method result is empty also muddies these waters too.

I've left this out for now; if you really want can potentially add a special case for all of this in Theories though (I'd suggest doing it for AllMembersSupplier too in that case). Alternatively we can look into a design for ValidatableParameterSupplier's, but I had a quick play around with that idea and it didn't click too well (for starters we have to build a whole supplier instance at init time, call validate with enough (?) context for the supplier to decide, just to then throw that supplier away). Either way I think this is getting somewhat outside of the scope of this pull request. Ideas welcome.