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cmd/cover: go test coverprofile wrong path at panic backtrace #20909

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minaevmike opened this issue Jul 5, 2017 · 3 comments
Closed

cmd/cover: go test coverprofile wrong path at panic backtrace #20909

minaevmike opened this issue Jul 5, 2017 · 3 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Milestone
Go1.10

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@minaevmike
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Please answer these questions before submitting your issue. Thanks!

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

go version go1.8.3 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/prog/GO"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build530360851=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

i make a simpe code to reproduce
file i.go

package sample
type I interface {
	Test()
}

type iI struct {

}

func (_ *iI) Test() {
	panic("t")
}

file sample_test.go

package sample

import "testing"

func Test_Panic(t *testing.T) {
	I := &iI{}
	I.Test()
}

What did you expect to see?

if i run this test without coverage i have normal panic backtrace

root@mike:~/prog/GO/src/github.com/minaevmike/sample/ss# go test
--- FAIL: Test_Panic (0.00s)
panic: t [recovered]
	panic: t

goroutine 5 [running]:
testing.tRunner.func1(0xc420072410)
	/usr/local/go/src/testing/testing.go:622 +0x29d
panic(0x50ad40, 0xc42000ee40)
	/usr/local/go/src/runtime/panic.go:489 +0x2cf
github.com/minaevmike/sample/ss.(*iI).Test(0x5ef6a0)
	/root/prog/GO/src/github.com/minaevmike/sample/ss/i.go:11 +0x64
github.com/minaevmike/sample/ss.Test_Panic(0xc420072410)
	/root/prog/GO/src/github.com/minaevmike/sample/ss/sample_test.go:7 +0x3b
testing.tRunner(0xc420072410, 0x5422e8)
	/usr/local/go/src/testing/testing.go:657 +0x96
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:697 +0x2ca
exit status 2
FAIL	github.com/minaevmike/sample/ss	0.003s

What did you see instead?

but if i run this test with coverprofile i have

root@mike:~/prog/GO/src/github.com/minaevmike/sample/ss# go test -v -coverprofile=c.out
=== RUN   Test_Panic
--- FAIL: Test_Panic (0.00s)
panic: t [recovered]
	panic: t

goroutine 5 [running]:
testing.tRunner.func1(0xc420072410)
	/usr/local/go/src/testing/testing.go:622 +0x29d
panic(0x50bde0, 0xc420012e40)
	/usr/local/go/src/runtime/panic.go:489 +0x2cf
github.com/minaevmike/sample/ss.(*iI).Test(0x5f06c0)
	github.com/minaevmike/sample/ss/_test/_obj_test/i.go:12 +0x6e
github.com/minaevmike/sample/ss.Test_Panic(0xc420072410)
	/root/prog/GO/src/github.com/minaevmike/sample/ss/sample_test.go:7 +0x3b
testing.tRunner(0xc420072410, 0x5434c8)
	/usr/local/go/src/testing/testing.go:657 +0x96
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:697 +0x2ca
exit status 2
FAIL	github.com/minaevmike/sample/ss	0.003s

So from this backtrace i can't undestand the line of code where panic was throw.
As i can undestand this path github.com/minaevmike/sample/ss/_test/_obj_test/i.go:12 is relative path to /tmp/go-build* dir. But it's impossible to detect the right folder. And this only happens when i run go test with coverprofile
@bradfitz bradfitz changed the title go test coverprofile wrong path at panic backtrace cmd/cover: go test coverprofile wrong path at panic backtrace Jul 5, 2017
@bradfitz bradfitz added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jul 5, 2017
@bradfitz bradfitz added this to the Go1.10 milestone Jul 5, 2017
@robpike
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robpike commented Jul 5, 2017

I'm not sure I understand. Are you saying that it says line 12 rather than line 11? That's the only difference I can see. That is a known and documented issue: The line numbers for crashes and test reports are incorrect when covering is enabled.

@minaevmike
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Yes, you're right. line 12 rather then line11. This behaviour make tests harder to debug in case of panic. I don't know how go test works inside, but mb it's possible to print full path to the file like /tmp/go-build123/github.com/minaevmike/sample/ss/_test/_obj_test/i.go:12 or recover this panic and map this path to the source path.

@robpike
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robpike commented Jul 6, 2017 •
edited

As "go help testflag" says,

BUG: If a compilation or test fails with coverage enabled,
the reported line numbers may be incorrect.

It's all but impossible to fix because of the way the go/ast package handles comments.

Unfortunate but unfixable.

However, there is some optimism that it can be fixed, according to #15757, of which this issue is a duplicate.

@robpike robpike closed this as completed Jul 6, 2017
@golang golang locked and limited conversation to collaborators Jul 6, 2018
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