testing: streaming output loses parallel subtest associations [1.14 backport]

[gopherbot]

@bcmills requested issue #38458 to be considered for backport to the next 1.14 minor release.

@gopherbot, please backport to Go 1.14: the 1.14 output format breaks go test -json for parallel subtests, and backporting the fix to the output format is likely to be more maintainable than a one-off test2json fix that is only used for the 1.14 branch.

[dmitshur]

@bcmills Do I understand correctly that backporting this to 1.14 will improve readability of the test output for humans, and fix a bug in go test -json (used by machines), so the behavior change from backporting it should be safe for a minor release?

Does the fix involve backporting both CL 229085 and CL 235997?

[bcmills]

Yes, your understanding of the behavior change is correct.

I would recommend backporting both changes, although only the first one is strictly necessary to fix the bug. You'll also want to pull in CL 234978 either way.

[dmitshur]

Thanks.

We've discussed this in a release meeting yesterday, and while it's unfortunate to be making a change, it is fixing a serious issue without a workaround. Approving for 1.14 (this issue doesn't affect 1.13).

[mdwhatcott]

@bcmills - Is this on track for 1.14.5?

[medyagh]

in minikube CI we have a bug (kubernetes/minikube#8349) that depends on fixing this issue
more info here
#33419 (comment)