internal/registrytest: do not assume subdirectory

This will make it easier to have the contents of several
registries contained in the same txtar file.

Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: I8a6810efd17bb9afdd325f070e1ab97b533c7ff5
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1170882
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

cmd/cue/cmd/script_test.go

@@ -108,14 +108,15 @@ func TestScript(t *testing.T) {
 				"GONOSUMDB=*", // GOPROXY is a private proxy
 				homeEnvName()+"="+home,
 			)
-			if info, err := os.Stat(filepath.Join(e.WorkDir, "_registry")); err == nil && info.IsDir() {
+			registryDir := filepath.Join(e.WorkDir, "_registry")
+			if info, err := os.Stat(registryDir); err == nil && info.IsDir() {
+				// There's a _registry directory. Start a fake registry server to serve
+				// the modules in it.
 				prefix := ""
 				if data, err := os.ReadFile(filepath.Join(e.WorkDir, "_registry_prefix")); err == nil {
 					prefix = strings.TrimSpace(string(data))
 				}
-				// There's a _registry directory. Start a fake registry server to serve
-				// the modules in it.
-				reg, err := registrytest.New(os.DirFS(e.WorkDir), prefix)
+				reg, err := registrytest.New(os.DirFS(registryDir), prefix)
 				if err != nil {
 					return fmt.Errorf("cannot start test registry server: %v", err)
 				}

cue/load/module_test.go

@@ -2,6 +2,7 @@ package load_test
 
 import (
 	"fmt"
+	"io/fs"
 	"testing"
 
 	"cuelabs.dev/go/oci/ociregistry/ociclient"
@@ -17,7 +18,11 @@ func TestModuleFetch(t *testing.T) {
 		Name: "modfetch",
 	}
 	test.Run(t, func(t *cuetxtar.Test) {
-		r, err := registrytest.New(registrytest.TxtarFS(t.Archive), "")
+		rfs, err := fs.Sub(registrytest.TxtarFS(t.Archive), "_registry")
+		if err != nil {
+			t.Fatal(err)
+		}
+		r, err := registrytest.New(rfs, "")
 		if err != nil {
 			t.Fatal(err)
 		}

internal/registrytest/registry.go

@@ -117,11 +117,11 @@ type handler struct {
 func getModules(fsys fs.FS) (map[module.Version]*moduleContent, error) {
 	ctx := cuecontext.New()
 	modules := make(map[string]*moduleContent)
-	if err := fs.WalkDir(fsys, "_registry", func(path string, d fs.DirEntry, err error) error {
+	if err := fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
-			// If a filesystem has no _registry directory at all,
+			// If a filesystem has no entries at all,
 			// return zero modules without an error.
-			if path == "_registry" && errors.Is(err, fs.ErrNotExist) {
+			if path == "." && errors.Is(err, fs.ErrNotExist) {
 				return fs.SkipAll
 			}
 			return err