! go mod init
stderr 'go: modules disabled by GO111MODULE=off; see ''go help modules'''
! go mod graph
stderr 'go: modules disabled by GO111MODULE=off; see ''go help modules'''
! go mod verify
stderr 'go: modules disabled by GO111MODULE=off; see ''go help modules'''
! go mod download
stderr 'go: modules disabled by GO111MODULE=off; see ''go help modules'''

	stdout := &bytes.Buffer{}
	stderr := &bytes.Buffer{}
	externalCommand.Stdout = stdout
	externalCommand.Stderr = stderr

	err := externalCommand.Run()

	if len(stdout.String()) != 0 {
		log.Debugf("Command output: \n%v", stdout.String())
	}

	if err != nil || len(stderr.Bytes()) != 0 {
		log.Debugf("Command error output: \n%v", stderr.String())
		return errors.New(stderr.String())
	}

	return nil

! go vet a/a.go
stderr '^package command-line-arguments\n\ta[/\\]a.go:5:3: use of internal package'

! go vet a/a_test.go
stderr '^package command-line-arguments \(test\)\n\ta[/\\]a_test.go:4:3: use of internal package'

! go vet a
stderr '^package a\n\ta[/\\]a.go:5:3: use of internal package'

go vet b/b.go
! stderr 'use of internal package'

! go vet b/b_test.go

env GO111MODULE=on

# argument doesn't have .go suffix and has no version
! go get test
! stderr 'arguments must be package or module paths'
! stderr 'exists as a file, but ''go get'' requires package arguments'

# argument has .go suffix and has version
! go get test.go@v1.0.0
! stderr 'arguments must be package or module paths'
! stderr 'exists as a file, but ''go get'' requires package arguments'

	cmd := exec.Command(exe)
	cmd.Stderr = new(strings.Builder)
	cmd.Env = append(os.Environ(), "GO_RUNTIME_DEBUG_TEST_ENTRYPOINT=setcrashoutput", "CRASHOUTPUT="+crashOutput)
	err = cmd.Run()
	stderr := fmt.Sprint(cmd.Stderr)
	if err == nil {
		t.Fatalf("child process succeeded unexpectedly (stderr: %s)", stderr)
	}
	t.Logf("child process finished with error %v and stderr <<%s>>", err, stderr)

! go run $PWD
! stderr 'no packages loaded'
stderr '^package example.net/nonmain is not a main package$'

! go run .
stderr '^package example.net/nonmain is not a main package$'

! go run ./...
stderr '^go: warning: "\./\.\.\." matched only non-main packages$'
stderr '^go: no packages loaded from \./\.\.\.$'

-- go.mod --
module example.net/nonmain

go 1.17
-- nonmain.go --
// Package nonmain is not a main package.

# errors as 'go build' and 'go list'.

! go build
stderr '^found packages m \(m\.go\) and main \(main\.go\) in '$PWD'$'

! go list .
stderr '^found packages m \(m\.go\) and main \(main\.go\) in '$PWD'$'

! go run .
! stderr 'no packages loaded'
stderr '^found packages m \(m\.go\) and main \(main\.go\) in '$PWD'$'

! go run ./...
! stderr 'no packages loaded'
stderr '^found packages m \(m\.go\) and main \(main\.go\) in '$PWD'$'

# Get errors from a go test into stderr.txt
! go test coverbad
stderr 'p\.go:4:2' # look for error at coverbad/p.go:4
[cgo] stderr 'p1\.go:6:2' # look for error at coverbad/p.go:6
! stderr $WORK # make sure temporary directory isn't in error

cp stderr $WORK/stderr.txt

# Get errors from coverage into stderr2.txt
! go test -cover coverbad
cp stderr $WORK/stderr2.txt

wait # for go run above

			}
			if len(f) > 2 {
				fmt.Fprintf(os.Stderr, "?usage: tags [prefix]\n")
				continue
			}
			tags, err := repo.Tags(prefix)
			if err != nil {
				fmt.Fprintf(os.Stderr, "?%s\n", err)
				continue
			}
			for _, tag := range tags {
				fmt.Printf("%s\n", tag)
			}

		case "stat":
			if len(f) != 2 {
				fmt.Fprintf(os.Stderr, "?usage: stat rev\n")
				continue
			}
			info, err := repo.Stat(f[1])

stderr '^go: added toolchain go1.999testmod$'
grep 'go 1.21' go.mod
grep 'toolchain go1.999testmod' go.mod

# Bug fixes.

# go get go@garbage should fail but not crash
! go get go@garbage
! stderr panic
stderr '^go: invalid go version garbage$'

# go get go@go1.21.0 is OK - we silently correct to 1.21.0
go get go@1.19
go get go@go1.21.0
stderr '^go: upgraded go 1.19 => 1.21.0'