This doesn't seem to be working, CI failing with missing hello. Does it need quoting?

I think we won't be able to do go test ./... -timing unless all test packages import testutil, a shortcoming of using flags in tests. I think the only way around it would be to use build tags instead but maybe this won't be an issue.

Hmm, I explored build tags but decided against it because it could lead to file bloat.

Let me know what you think about ba6f151.

Hmm, I explored build tags but decided against it because it could lead to file bloat.

I was thinking it could be contained to the testutil package using the checking function you already implemented, so only 1 more file should be necessary. The build tag would then decide if the test becomes enabled or not.

Example:

//go:build timing

package testutil

var _ = func() any {
	timing = true
	return nil
}()

(Or use init, but the above avoids using that reserved name, tags/duped func in both files is another option.)

This would allow running the entire test suite with go test ./... -tags=timing. Or limiting to timing tests via go test ./... -tags=timing -run='_Timing$'.

Let me know what you think about ba6f151.

I think that looks alright since it requires an intent to run, otherwise generating go_tests.json would be too slow.

Nice idea, let's go that way. See new code.

Let's replace this with a require btw.