x/tools/gopls/test/debug: test fails when run in the module cache

[bcmills]

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

(Built from CL 489076 patchset 2.)

$ go version
go version devel go1.21-0e5f77a24c Fri Apr 21 14:45:51 2023 -0400 linux/amd64

Does this issue reproduce with the latest release?

Yes, but it's harder to reproduce due to #56222.

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/usr/local/google/home/bcmills/.cache/go-build"
GOENV="/usr/local/google/home/bcmills/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/tmp/tmp.hIhiXWubgo/.gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/tmp/tmp.hIhiXWubgo/.gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/google/home/bcmills/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/google/home/bcmills/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel go1.21-0e5f77a24c Fri Apr 21 14:45:51 2023 -0400"
GCCGO="/usr/bin/gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="c++"
CGO_ENABLED="1"
GOMOD="/tmp/tmp.hIhiXWubgo/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2658695689=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ go mod init example
go: creating new go.mod: module example

$ go get -t golang.org/x/tools/gopls/test/debug@master golang.org/x/tools@master
go: added golang.org/x/tools v0.8.1-0.20230425201836-76e1037d71f8
go: added golang.org/x/tools/gopls v0.0.0-20230425201836-76e1037d71f8

$ go test golang.org/x/tools/gopls/test/debug

What did you expect to see?

The test should either pass or be skipped.

What did you see instead?

The test fails: it assumes that the golang.org/x/tools module is located up from the gopls module, but that assumption does not hold in the module cache. (Instead, the two modules are downloaded independently and stored in disjoint subtrees.)

$ go test golang.org/x/tools/gopls/test/debug
--- FAIL: TestTemplates (2.32s)
    debug_test.go:61: compiler error, e.g. /tmp/tmp.hIhiXWubgo/.gopath/pkg/mod/golang.org/x/tools/[email protected]/internal/lsp/debug/metrics.go:8:2: could not import golang.org/x/tools/internal/event/export/metric (invalid package name: "")
FAIL
FAIL    golang.org/x/tools/gopls/test/debug     2.377s
FAIL

[gopherbot]

Change https://go.dev/cl/489216 mentions this issue: test/debug: load packages from outside the gopls module

[gopherbot]

Change https://go.dev/cl/489215 mentions this issue: internal/gocommand: simplify GoVersion invocation

[gopherbot]

Change https://go.dev/cl/489235 mentions this issue: internal/lsp/safetoken: load packages in TestGoplsSourceDoesNotCallTokenFileMethods from outside the gopls module