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cmd/cover: zero coverage for cgo project #13625

zhulik opened this issue Dec 15, 2015 · 4 comments

cmd/cover: zero coverage for cgo project #13625

zhulik opened this issue Dec 15, 2015 · 4 comments


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@zhulik zhulik commented Dec 15, 2015

Hi, i writing bindings for libmediainfo and when i start to write tests i noted, that coverage is 0.0% and coverprofile is empty, i don't see any files in dropdown when doing go tool cover -html=coverage.out.

go version go1.5.2 linux/amd64

Steps to reproduce:

git clone
cd go_mediainfo
go test -cover

I know, that this is not first issue with cgo and coverage, #6333 is closed over a year ago, but i have the same issue now.

@ianlancetaylor ianlancetaylor changed the title Zero coverage for cgo project cmd/cover: zero coverage for cgo project Dec 15, 2015
@ianlancetaylor ianlancetaylor added this to the Go1.7 milestone Dec 15, 2015
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@bradfitz bradfitz commented Apr 8, 2016

@robpike, is cmd/cover compatible with cgo?

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@robpike robpike commented Apr 8, 2016

It's supposed to. See #6333.

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@ALTree ALTree commented May 14, 2016

Simple reproducer:


package rand

#include <stdlib.h>
import "C"

func Random() int {
    return int(C.random())

func Seed(i int) {


package rand_test

import (


func TestRandom(t *testing.T) {
    x := rand.Random()
    if x < 0 {
        t.Fatalf("%d < 0\n", x)

go test -cover gives 0.0% if and only if the tests are in a separate package (in this case, rand_test). If the package declaration in rand_test.go is changed to package rand, -cover reports a correct value; and that is the reason the test introduced in CL 71230049 by rsc didn't catch the problem (that test has package p for both the cgo file and the _test file).

@rsc rsc modified the milestones: Go1.8, Go1.7 May 17, 2016
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@gopherbot gopherbot commented Nov 3, 2016

CL mentions this issue.

@gopherbot gopherbot closed this in 1c08c72 Nov 3, 2016
@golang golang locked and limited conversation to collaborators Nov 3, 2017
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