cmd/go: -coverpkg packages imported by all tests, even ones that otherwise do not use it

[ChrisHines]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.10 windows/amd64

Does this issue reproduce with the latest release?

Yes.

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

set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\Chris\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=C:\Users\Chris\Go
set GORACE=
set GOROOT=C:\Go
set GOTMPDIR=
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=C:\Users\Chris\AppData\Local\Temp\go-build675280250=/tmp/go-build -gno-record-gcc-switches

What did you do?

>go get github.com/ChrisHines/coverpkgtest

>cd $GOPATH/github.com/ChrisHines/coverpkgtest

>go run main.go
9

>go test ./...
?       github.com/ChrisHines/coverpkgtest      [no test files]
ok      github.com/ChrisHines/coverpkgtest/subdir       (cached)

>go test -coverpkg=./... .
?       github.com/ChrisHines/coverpkgtest      [no test files]

>go test -coverpkg=./... ./subdir
ok      github.com/ChrisHines/coverpkgtest/subdir       0.052s  coverage: 0.0% of statements in ./...

>go test -coverpkg=. ./subdir
warning: no packages being tested depend on matches for pattern .
ok      github.com/ChrisHines/coverpkgtest/subdir       0.057s  coverage: 0.0% of statements in .

>go test -coverpkg=. ./...
?       github.com/ChrisHines/coverpkgtest      [no test files]
panic: open tmpl.txt: The system cannot find the file specified.

goroutine 1 [running]:
text/template.Must(0x0, 0x5c8ba0, 0xc042064390, 0x1)
        C:/Go/src/text/template/helper.go:23 +0x5b
FAIL    github.com/ChrisHines/coverpkgtest/subdir       0.056s

>go test -coverpkg=./... ./...
?       github.com/ChrisHines/coverpkgtest      [no test files]
panic: open tmpl.txt: The system cannot find the file specified.

goroutine 1 [running]:
text/template.Must(0x0, 0x5c8ba0, 0xc042074390, 0x1)
        C:/Go/src/text/template/helper.go:23 +0x5b
FAIL    github.com/ChrisHines/coverpkgtest/subdir       0.055s

What did you expect to see?

I expected the tests to pass regardless of how they are launched by the go tool.

What did you see instead?

Using -coverpkg=./... in combination with the test package pattern ./... caused a panic for a missing file even though the file exists. It is also confusing that running the tests on individual packages or without -coverpkg=./... does not panic.

[ianlancetaylor]

I think the problem is that cmd/go rewrites tests to import all packages listed in -coverpkgs. It then runs the test for package subdir in the subdir directory. In your case the main package is listed in -coverpkgs, so the test imports it. The only thing that is run in the main package is the initializers. In your program that is what fails: the initializer loads a relative file and can only run in the main package directory, not in the subdirectory.

Not sure what the right fix is.

[rsc]

/cc @bcmills

[nvartolomei]

Sounds like #27336

[forsaken628]

test

go test -v -coverpkg=./... ./...

-- go.mod --
module test
-- main.go --
package main

import "flag"

func init() { flag.Parse() }
-- bar/bar.go --
package bar
-- bar/bar_test.go --
package bar

--- FAIL: TestScript (0.01s)
    --- FAIL: TestScript/test_cover_main_init (1.22s)
        script_test.go:213: 
            > go test -v -coverpkg=./... ./...
            [stdout]
            ?           test    [no test files]
            flag provided but not defined: -test.testlogfile
            Usage of $WORK/tmp/go-build1087252013/b037/bar.test:
            FAIL        test/bar        0.779s
            FAIL
            [exit status 1]
            FAIL: testdata/script/test_cover_main_init.txt:1: unexpected command failure
            
FAIL
FAIL    cmd/go  2.598s
FAIL

link
https://golang.org/cl/278892

maybe skip main package without test files

Index: src/cmd/go/internal/test/test.go
<+>UTF-8
===================================================================
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
--- a/src/cmd/go/internal/test/test.go	(revision dfaf69eccc66f44e9ca150d062baadf53c574438)
+++ b/src/cmd/go/internal/test/test.go	(revision cfab536ac976f7597165cfac002c80cc6613ad5f)
@@ -731,6 +731,11 @@
 				continue
 			}

+			// Don't call main.init, if no test file.
+			if p.Name == "main" && len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
+				continue
+			}
+
 			if haveMatch {
 				testCoverPkgs = append(testCoverPkgs, p)
 			}

[slinkydeveloper]

If you want to try a bigger project to reproduce the issue, clone https://github.com/knative/eventing and run the test with:

go test -race -coverpkg=./... ./...

For more details: knative/pkg#2113

[thanm]

FYI, we've moved away from the model in which all -coverpkg packages are force-imported into every test, this was done as part of the coverage redesign in Go 1.20. This is spawn a few bugs (ex: #58770) but I have a fix out for review that should resolve that (https://go.dev/cl/495452). Closing this bug out, please reopen if needed.