cmd/go: coverpkg broken behaviour in version 1.10.1

[apremalal]

Please answer these questions before submitting your issue. Thanks!

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

go1.10.1 darwin/amd64

Does this issue reproduce with the latest release?

yes

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

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/ag/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/ag/workspace"
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/2t/8v5wp6zn36n2fgxf5qvd75zw0000gq/T/go-build821224783=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

My repo structure is like below, and I'm executing commands indie folder

<go-test-cov>
 |
  -<models>
 |
  -<models-test>

I have hosted the code in github for easy referencing.

models/math.go

package models

func Add(x,y int) int{
  return x+y
}

models_test/math_test.go

package models_test

import (
   "testing"
  "github.com/apremalal/go-test-cov/models"
)

func TestAdd(t *testing.T) {
    total := models.Add(5, 5)
    if total != 10 {
       t.Errorf("Sum was incorrect, got: %d, want: %d.", total, 10)
    }
}

I tried the following command which worked in golang 1.9.X versions. And gave me correct coverage results

go test -v ./models_test -coverpkg=./models -coverprofile=c.out && go tool cover -func=c.out

But with version 1.10.1 it throws a warning saying

no packages being tested depend on matches for pattern ./models

And the coverage is always 0% with the above command

What did you expect to see?

100% test coverage

What did you see instead?

0% test coverage

[majewsky]

I can reproduce the issue with package github.com/majewsky/schwift and Go 1.10.1. Downgrading to Go 1.9.4 fixes the problem for me.

[majewsky]

Still reproducible with Go 1.10.2. Furthermore, I noticed that the warning that @apremalal mentions also exists in 1.9.4 (where coverage is reported correctly), but is worded slightly differently. With Go 1.9.4:

$ go test -covermode count -coverpkg github.com/majewsky/schwift,github.com/majewsky/schwift/gopherschwift  -coverprofile cover.out github.com/majewsky/schwift/tests
warning: no packages being tested depend on github.com/majewsky/schwift
warning: no packages being tested depend on github.com/majewsky/schwift/gopherschwift
ok      github.com/majewsky/schwift/tests       14.399s coverage: 80.3% of statements in github.com/majewsky/schwift, github.com/majewsky/schwift/gopherschwift

Same command with Go 1.10.2:

warning: no packages being tested depend on matches for pattern github.com/majewsky/schwift
warning: no packages being tested depend on matches for pattern github.com/majewsky/schwift/gopherschwift
ok      github.com/majewsky/schwift/tests       12.036s coverage: 0.0% of statements in github.com/majewsky/schwift, github.com/majewsky/schwift/gopherschwift

This makes me think that e33794f is where the error was introduced. I did not have the time to do a bisect, though.

[gopherbot]

Change https://golang.org/cl/122555 mentions this issue: cmd/go: search test imports when matching -coverpkg

[vaishali-ntnx]

In which release this fix is available?

[davecheney]

Go 1.11

[vaishali-ntnx]

Thanks @davecheney

[TACIXAT]

Sorry to bump this, but for the search indexers:

If you're really confused about how to get code coverage for an external package or imported package in golang, you might be running into this bug. Update to 1.11+, then -coverpkg will work with the package name.