cmd/go: unexpected panic when running go test on particular package without test files

[mark-rushakoff]

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

gotip version
go version devel +7b08e619bb Thu Jun 7 16:17:04 2018 +0000 darwin/amd64

Does this issue reproduce with the latest release?

I tested with go1.10.1 and it does not reproduce.

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

$ gotip env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/mr/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/mr/go"
GORACE=""
GOROOT="/Users/mr/gotip/src/github.com/golang/go"
GOTMPDIR=""
GOTOOLDIR="/Users/mr/gotip/src/github.com/golang/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/ct/bl4_z3g51ks8239_r2k07v_40000gn/T/go-build990290390=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I created a repository that you can clone to reproduce this issue: https://github.com/mark-rushakoff/testpanic

I am sure the repro case could be stripped down quite a bit, but I do not have time to minimize it any further right now.

That repository's main.go contains only the following code:

package main

import (
	"net/http"

	"github.com/elazarl/goproxy"
	"github.com/sirupsen/logrus"
)

func main() {
	proxy := goproxy.NewProxyHttpServer()
	proxy.Verbose = true
	logrus.Fatal(http.ListenAndServe(":8080", proxy))
}

Then I ran go test .

What did you expect to see?

I expected to see the same output that I see in go 1.10:

go test .
?       github.com/mark-rushakoff/testpanic     [no test files]

What did you see instead?

I saw a panic from an init function, that I would not have expected to run on account of there being no test files:

$ GOTRACEBACK=system gotip test .
panic: Error parsing builtin CA x509: RSA key missing NULL parameters

goroutine 1 [running]:
panic(0x1271080, 0xc000049060)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/panic.go:537 +0x2cb fp=0xc000115df0 sp=0xc000115d60 pc=0x102cbfb
github.com/mark-rushakoff/testpanic/vendor/github.com/elazarl/goproxy.init.0()
        /Users/mr/go/src/github.com/mark-rushakoff/testpanic/vendor/github.com/elazarl/goproxy/certs.go:10 +0x1bc fp=0xc000115e58 sp=0xc000115df0 pc=0x1240b0c
github.com/mark-rushakoff/testpanic/vendor/github.com/elazarl/goproxy.init()
        <autogenerated>:1 +0x250 fp=0xc000115f78 sp=0xc000115e58 pc=0x1240d70
github.com/mark-rushakoff/testpanic.init()
        <autogenerated>:1 +0x4a fp=0xc000115f88 sp=0xc000115f78 pc=0x1243faa
main.init()
        <autogenerated>:1 +0x54 fp=0xc000115f98 sp=0xc000115f88 pc=0x1244254
runtime.main()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:189 +0x1bd fp=0xc000115fe0 sp=0xc000115f98 pc=0x102e8ad
runtime.goexit()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc000115fe8 sp=0xc000115fe0 pc=0x105b941

goroutine 2 [force gc (idle)]:
runtime.gopark(0x12eb408, 0x14ea090, 0x1410, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:298 +0xeb fp=0xc000032f80 sp=0xc000032f60 pc=0x102eceb
runtime.goparkunlock(0x14ea090, 0x1410, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:304 +0x53 fp=0xc000032fb0 sp=0xc000032f80 pc=0x102ed93
runtime.forcegchelper()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:251 +0xb3 fp=0xc000032fe0 sp=0xc000032fb0 pc=0x102eb63
runtime.goexit()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc000032fe8 sp=0xc000032fe0 pc=0x105b941
created by runtime.init.4
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:240 +0x35

goroutine 3 [GC sweep wait]:
runtime.gopark(0x12eb408, 0x14ea1e0, 0x102140c, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:298 +0xeb fp=0xc000033780 sp=0xc000033760 pc=0x102eceb
runtime.goparkunlock(0x14ea1e0, 0x131140c, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:304 +0x53 fp=0xc0000337b0 sp=0xc000033780 pc=0x102ed93
runtime.bgsweep(0xc00006a000)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/mgcsweep.go:52 +0x8f fp=0xc0000337d8 sp=0xc0000337b0 pc=0x1020b5f
runtime.goexit()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc0000337e0 sp=0xc0000337d8 pc=0x105b941
created by runtime.gcenable
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/mgc.go:216 +0x58

goroutine 4 [finalizer wait]:
runtime.gopark(0x12eb408, 0x1507da0, 0x129140f, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:298 +0xeb fp=0xc000032728 sp=0xc000032708 pc=0x102eceb
runtime.goparkunlock(0x1507da0, 0x140f, 0x1)
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/proc.go:304 +0x53 fp=0xc000032758 sp=0xc000032728 pc=0x102ed93
runtime.runfinq()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/mfinal.go:175 +0x99 fp=0xc0000327e0 sp=0xc000032758 pc=0x10185b9
runtime.goexit()
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc0000327e8 sp=0xc0000327e0 pc=0x105b941
created by runtime.createfing
        /Users/mr/gotip/src/github.com/golang/go/src/runtime/mfinal.go:156 +0x61
FAIL    github.com/mark-rushakoff/testpanic     0.017s

[ianlancetaylor]

The go tool does now build and run the test binary even if there aren't any tests. If this didn't happen in 1.10, it happens on tip most likely because of #24570. It does seem simpler to handle things consistently, rather than having a special case when there are no tests.

[rsc]

Duplicate (now) of #26242, which we will fix for Go 1.11.

[gopherbot]

Change https://golang.org/cl/122518 mentions this issue: cmd/go: revert "output coverage report even if there are no test files"