testing: move Internal types to internal package

[bradfitz]

InternalBenchmark, InternalExample, and InternalTest predate the "internal" package mechanism.

Per a discussion here, we could probably move those three into a new internal package, and add a type alias for a few cycles before removing the testing alias.

[rsc]

This seems like a likely accept given the reactions over the past two weeks.
/cc @mpvl

Leaving open for a week for final comments.

[rsc]

No change in consensus, so accepting.

[tpaschalis]

Hey @bradfitz! Sorry for pinging, but I'd like to take a stab on this issue if that's okay with you!

From what I gather, we'd like move InternalBenchmark, InternalExample, and InternalTest into a new package most likely in src/internal/testing, or src/testing/internal.

Then, to avoid confusion during a couple of releases, we'd also like to alias them to their older names like type InternalBenchmark = internal.Benchmark.

I hope I'm not completely off the mark; please let me know if I've missed anything and I'll try to get a CL opened soon!

[tpaschalis]

I tried my hand on this; moving InternalBenchmark and InternalTest meant moving types T and B and their common interface as well to avoid cyclical dependencies.

It cascades to more changes than I anticipated, but I'll still open that CL in the next days and hopefully get some feedback.

[gopherbot]

Change https://golang.org/cl/247057 mentions this issue: testing: move Internal types to internal package

[ianlancetaylor]

@arnottcr took a stab at this in https://golang.org/cl/247057, and the resulting change is pretty big and has ramifications like changing the names of user visible types. Unless we can find a simpler approach, I don't think we should actually do this.

[urandom2]

While I find it problematic that one of the blocking arguments is that, type alias documentation is a bad ux and #44905 was closed without resolution; I agree this change is probably too large to justify otherwise, should we close it out?

[rsc]

I agree - we did not consider the references InternalTest -> T and InternalBenchmark -> B.
It does not make any sense to move testing.T and testing.B to another package and make them type aliases.
Let's close this.