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cmd/cover: Some code are missed by Go coverage profile #59563

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rumtid opened this issue Apr 12, 2023 · 7 comments
Closed

cmd/cover: Some code are missed by Go coverage profile #59563

rumtid opened this issue Apr 12, 2023 · 7 comments
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NeedsFix The path to resolution is known, but the work has not been done.

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@rumtid
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rumtid commented Apr 12, 2023 •
edited

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

$ go version
go version go1.20.3 darwin/amd64

Does this issue reproduce with the latest release?

Yes. Also, go1.19.8 works fine.

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

darwin, amd64

What did you do?

Run:

$ git clone https://github.com/rumtid/parser.git
$ cd parser

$ /usr/local/go/bin/go test -timeout 30s -coverprofile=/var/folders/ry/vp2b73b17vq3_w50fsqt1xp80000gn/T/vscode-goaU9l71/go-code-cover -run ^TestMe$ github.com/rumtid/parser -coverpkg=all

What did you expect to see?

The coverage profile marks some covered lines in yyParse().

What did you see instead?

Despite yyParse() is invoked, it is not covered according to the profile.
@rumtid rumtid changed the title Some code are missed by Go coverage profile cmd/cover: Some code are missed by Go coverage profile Apr 12, 2023
@ianlancetaylor
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CC @thanm

@thanm
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thanm commented Apr 12, 2023

Thanks for the report. I will take a look.

@thanm
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thanm commented Apr 13, 2023

OK, I think I see what's going on here. I will send a fix shortly.

What's happening here is a side effect of -coverpkg=all, in which we gather coverage data from everything, including the Go runtime and a lot of other low-level packages. This in turn means that the underlying coverage counters can be changing even as the data is being written out, which is the source of this particular bug.

As a workaround, I recommend picking out just the packages that you are actually interested in and passing those to -coverpkg; doing that won't expose you to this particular problem.

@dr2chase dr2chase added the NeedsFix The path to resolution is known, but the work has not been done. label Apr 13, 2023
@gopherbot
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Change https://go.dev/cl/484535 mentions this issue: coverage: fix count vs emit discrepancy in coverage counter data writing

@rumtid
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rumtid commented Apr 14, 2023

I see, thanks a lot.

@gopherbot
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Change https://go.dev/cl/492175 mentions this issue: runtime/coverage: fix problematic test from issue 59563

gopherbot pushed a commit that referenced this issue May 3, 2023
@thanm @gopherbot
runtime/coverage: fix problematic test from issue 59563
91a716a 
Fix up the coverage testpoint TestIssue59563TruncatedCoverPkgAll
to avoid spurious failures due to racy behavior. Specifically,
we are only interested in verifying coverage for the larger
function of the two in the test package (the smaller one is only
there to trigger additional function registrations while the
test is finalizing the cov data).

Updates #59867.
Updates #59563.

Change-Id: Ibfbbcbf68e0ad7a4d9606cbcfc69d140375c7b87
Reviewed-on: https://go-review.googlesource.com/c/go/+/492175
Run-TryBot: Than McIntosh <thanm@google.com>
Auto-Submit: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
@gopherbot
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Change https://go.dev/cl/492981 mentions this issue: internal/coverage/encodecounter: followup changes from code review

gopherbot pushed a commit that referenced this issue May 5, 2023
@thanm
internal/coverage/encodecounter: followup changes from code review
695a536 
This patch contains a small set of changes with fixes for some
issues that surfaced during the code review for CL 484535. Due
to an error on my part, these never got included in the final version
that was checked in (I rebased, mailed the rebase, but then never
mailed the final patch set with the changes). This patch sends
the remaining bits and pieces.

Updates #59563.

Change-Id: I87dc05a83f8e44c8bfe7203bc2b035defc817af9
Reviewed-on: https://go-review.googlesource.com/c/go/+/492981
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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@dr2chase @ianlancetaylor @rumtid @gopherbot @thanm