cmd/go: coverage profile should be cached with tests

[bbrks]

As briefly discussed here: https://twitter.com/_rsc/status/956888213314068481

I don't see why Go shouldn't cache the results of -coverprofile when running tests, as test coverage shouldn't vary from run to run, given the same set of arguments.

What version of Go are you using (go version)?

go version go1.10rc1 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

$GOOS="darwin"
$GOARCH="amd64"

What did you do?

Call go test -coverprofile=coverprofile.out ./... multiple times.

What did you expect to see?

Test results cached between runs.

$ go test -coverprofile=coverprofile.out ./...
ok  	github.com/bbrks/tmp	2.893s	coverage: 46.1% of statements
$ go test -coverprofile=coverprofile.out ./...
ok  	github.com/bbrks/tmp	(cached)

What did you see instead?

Test results were not cached between runs.

$ go test -coverprofile=coverprofile.out ./...
ok  	github.com/bbrks/tmp	2.893s	coverage: 46.1% of statements
$ go test -coverprofile=coverprofile.out ./...
ok  	github.com/bbrks/tmp	2.893s	coverage: 46.1% of statements

[ianlancetaylor]

CC @rsc

[gopherbot]

Change https://golang.org/cl/90955 mentions this issue: cmd/go: coverage profile use cache if the set of arguements equals

[fgrosse]

I was hoping this change would make it into go1.11 but it seems its not working yet in go1.11beta3. Looking at the CL it seems it got stuck due to merge conflicts? Any chance we can pick up this issue and still include it in v11?

[bbrks]

@fgrosse Looks like it's being targeted for 1.12 now. I don't think it will be rescheduled this close to 1.11's release.

[fgrosse]

Alright, thanks for the update on this issue. Ben Brooks <notifications@github.com> schrieb am Mo., 6. Aug. 2018, 13:34:

…

@fgrosse <https://github.com/fgrosse> Looks like it's being targeted for 1.12 now. I don't think it will be rescheduled this close to 1.11's release. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#23565 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAsvTP9Zd6Qik3yRHeE5td0dAye-tjLeks5uOCnbgaJpZM4RuY2-> .

[nightlyone]

Is this still planned for Go1.12 ? I guess not...