"garble test" doesn't work with reflection

[huibeu]

Output of garble version:

mvdan.cc/garble v0.14.2

Build settings:
      -buildmode exe
       -compiler gc
  DefaultGODEBUG gotestjsonbuildtext=1,multipathtcp=0,randseednop=0,rsa1024min=0,tlsmlkem=0,x509rsacrt=0,x509usepolicies=0
     CGO_ENABLED 1
          GOARCH amd64
            GOOS linux
         GOAMD64 v1

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/root/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1753113114=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/root/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.5'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

go test gives errors, even when running tests on the std packages.

# This works
go test reflect
go test encoding/xml
go test encoding/json

# This gives failing tests and build errors
garble test reflect
garble test encoding/xml
garble test encoding/json

I did not see any issues when running code with garble run or garble build.

What did you see happen?

garble test reflect

# reflect.test
list flag: not found
FAIL	reflect [build failed]
FAIL
exit status 1

garble test encoding/xml

--- FAIL: TestMarshal (0.00s)
    --- FAIL: TestMarshal/2 (0.00s)
        ozLy15Wlr.go:1: marshal(&bvuKzfAhE4.Jp9cjKXs{MmON2eeJ:true}):
            have `<Jp9cjKXs><MmON2eeJ>true</MmON2eeJ></Jp9cjKXs>`
            want `<Plain><V>true</V></Plain>`
[...]
FAIL
FAIL	encoding/xml	3.234s
FAIL
exit status 1

garble test encoding/json

# encoding/json.test
list internal/fuzz: not found
FAIL	encoding/json [build failed]
FAIL
exit status 1

What did you expect to see?

I expected the output to look similar to running the tests with go test:

$ go test reflect
ok  	reflect	0.279s
$ go test encoding/xml
ok  	encoding/xml	3.360s
$ go test encoding/json
ok  	encoding/json	0.378s

[mvdan]

Being able to garble test the standard library is not an objective of this project. But patches are welcome if you want to work towards that.

[huibeu]

I used the tests of the standard library because I thought it would be easier to reproduce. I'm running into the same problem with my own tests. For example:

main.go:

package main

import (
	"encoding/xml"
	"fmt"
)

type Book struct {
	XMLName struct{} `xml:"book"`
	Title   string   `xml:",chardata"`
}

func getXML() string {
	book := &Book{Title: "My book"}
	data, _ := xml.Marshal(book)
	return string(data)
}

func main() {
	fmt.Println(getXML())
}

main_test.go:

package main

import "testing"

func TestGetXml(t *testing.T) {
	gotXml := getXML()
	wantXml := "<book>My book</book>"

	if gotXml != wantXml {
		t.Errorf("got  %v\n want %v", gotXml, wantXml)
	}
}

Output:

$ go run .  
<book>My book</book>

$ go test .
ok      garble-demo     0.001s

$ garble run .
<book>My book</book>

$ garble test .
--- FAIL: TestGetXml (0.00s)
    A8iPCAyf3f0_.go:1: got  <OReE6JEkJ1Rk><book></book>My book</OReE6JEkJ1Rk>
         want <book>My book</book>
FAIL
FAIL    garble-demo     0.002s
FAIL
exit status 1

Would you like me to create a new ticket? I did have a quick look at the garble source code but I couldn't find out why this would behave differently for tests.

[mvdan]

Very odd that garble run works, but garble test does not.

Thanks for clarifying this is not about testing the standard library.