diff --git a/cmd/cue/cmd/script_test.go b/cmd/cue/cmd/script_test.go
index 71ac01525..6fe1ce05f 100644
--- a/cmd/cue/cmd/script_test.go
+++ b/cmd/cue/cmd/script_test.go
@@ -52,7 +52,7 @@ import (
 	"cuelang.org/go/internal/cuetest"
 	"cuelang.org/go/internal/cueversion"
 	"cuelang.org/go/internal/mod/semver"
-	"cuelang.org/go/internal/registrytest"
+	"cuelang.org/go/mod/modregistrytest"
 )
 
 // TestLatest checks that the examples match the latest language standard,
@@ -169,7 +169,7 @@ func TestScript(t *testing.T) {
 				if neg {
 					usage()
 				}
-				var auth *registrytest.AuthConfig
+				var auth *modregistrytest.AuthConfig
 				if len(args) > 0 && strings.HasPrefix(args[0], "-") {
 					userPass, ok := strings.CutPrefix(args[0], "-auth=")
 					if !ok {
@@ -179,7 +179,7 @@ func TestScript(t *testing.T) {
 					if !ok {
 						usage()
 					}
-					auth = &registrytest.AuthConfig{
+					auth = &modregistrytest.AuthConfig{
 						Username: user,
 						Password: pass,
 					}
@@ -189,7 +189,7 @@ func TestScript(t *testing.T) {
 					usage()
 				}
 
-				srv, err := registrytest.NewServer(ocimem.NewWithConfig(&ocimem.Config{ImmutableTags: true}), auth)
+				srv, err := modregistrytest.NewServer(ocimem.NewWithConfig(&ocimem.Config{ImmutableTags: true}), auth)
 				if err != nil {
 					ts.Fatalf("cannot start registrytest server: %v", err)
 				}
@@ -294,7 +294,7 @@ func TestScript(t *testing.T) {
 						return fmt.Errorf("invalid contents of proxy file %q: %v", proxyFile, err)
 					}
 				}
-				reg, err := registrytest.New(os.DirFS(registryDir), prefix)
+				reg, err := modregistrytest.New(os.DirFS(registryDir), prefix)
 				if err != nil {
 					return fmt.Errorf("cannot start test registry server: %v", err)
 				}
diff --git a/cue/load/example_test.go b/cue/load/example_test.go
index d04338ab1..302ad2c8f 100644
--- a/cue/load/example_test.go
+++ b/cue/load/example_test.go
@@ -24,7 +24,7 @@ import (
 	"cuelang.org/go/cue"
 	"cuelang.org/go/cue/cuecontext"
 	"cuelang.org/go/cue/load"
-	"cuelang.org/go/internal/registrytest"
+	"cuelang.org/go/mod/modregistrytest"
 )
 
 // Note that these examples may not be runnable on pkg.go.dev,
@@ -135,7 +135,7 @@ value: "world"
 	if err != nil {
 		panic(err)
 	}
-	registry, err := registrytest.New(registryFS, "")
+	registry, err := modregistrytest.New(registryFS, "")
 	if err != nil {
 		panic(err)
 	}
diff --git a/cue/load/module_test.go b/cue/load/module_test.go
index 05f3d4899..95c5f6c61 100644
--- a/cue/load/module_test.go
+++ b/cue/load/module_test.go
@@ -15,8 +15,8 @@ import (
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/load"
 	"cuelang.org/go/internal/cuetxtar"
-	"cuelang.org/go/internal/registrytest"
 	"cuelang.org/go/mod/modcache"
+	"cuelang.org/go/mod/modregistrytest"
 )
 
 func TestModuleLoadWithInvalidRegistryConfig(t *testing.T) {
@@ -76,7 +76,7 @@ func TestModuleFetch(t *testing.T) {
 		qt.Assert(t, qt.IsNil(err))
 		rfs, err := fs.Sub(tfs, "_registry")
 		qt.Assert(t, qt.IsNil(err))
-		r, err := registrytest.New(rfs, "")
+		r, err := modregistrytest.New(rfs, "")
 		qt.Assert(t, qt.IsNil(err))
 		defer r.Close()
 
diff --git a/internal/mod/modload/tidy_test.go b/internal/mod/modload/tidy_test.go
index 8f75e837c..f0d8e1dee 100644
--- a/internal/mod/modload/tidy_test.go
+++ b/internal/mod/modload/tidy_test.go
@@ -16,9 +16,9 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"golang.org/x/tools/txtar"
 
-	"cuelang.org/go/internal/registrytest"
 	"cuelang.org/go/mod/modfile"
 	"cuelang.org/go/mod/modregistry"
+	"cuelang.org/go/mod/modregistrytest"
 	"cuelang.org/go/mod/module"
 )
 
@@ -85,7 +85,7 @@ func stringFromFile(fsys fs.FS, file string) string {
 func newRegistry(t *testing.T, fsys fs.FS) Registry {
 	fsys, err := fs.Sub(fsys, "_registry")
 	qt.Assert(t, qt.IsNil(err))
-	regSrv, err := registrytest.New(fsys, "")
+	regSrv, err := modregistrytest.New(fsys, "")
 	qt.Assert(t, qt.IsNil(err))
 	t.Cleanup(regSrv.Close)
 	regOCI, err := ociclient.New(regSrv.Host(), &ociclient.Options{
diff --git a/internal/mod/modrequirements/requirements_test.go b/internal/mod/modrequirements/requirements_test.go
index b811d48f8..6845bc1a9 100644
--- a/internal/mod/modrequirements/requirements_test.go
+++ b/internal/mod/modrequirements/requirements_test.go
@@ -10,9 +10,9 @@ import (
 	"golang.org/x/tools/txtar"
 
 	"cuelang.org/go/internal/mod/mvs"
-	"cuelang.org/go/internal/registrytest"
 	"cuelang.org/go/mod/modfile"
 	"cuelang.org/go/mod/modregistry"
+	"cuelang.org/go/mod/modregistrytest"
 	"cuelang.org/go/mod/module"
 )
 
@@ -216,7 +216,7 @@ func mustParseVersion(s string) module.Version {
 func newRegistry(t *testing.T, registryContents string) Registry {
 	regFS, err := txtar.FS(txtar.Parse([]byte(registryContents)))
 	qt.Assert(t, qt.IsNil(err))
-	regSrv, err := registrytest.New(regFS, "")
+	regSrv, err := modregistrytest.New(regFS, "")
 	qt.Assert(t, qt.IsNil(err))
 	t.Cleanup(regSrv.Close)
 	regOCI, err := ociclient.New(regSrv.Host(), &ociclient.Options{
diff --git a/mod/modcache/modcache_test.go b/mod/modcache/modcache_test.go
index 95ce9da2f..38e0bc402 100644
--- a/mod/modcache/modcache_test.go
+++ b/mod/modcache/modcache_test.go
@@ -15,8 +15,8 @@ import (
 	"github.com/go-quicktest/qt"
 	"golang.org/x/tools/txtar"
 
-	"cuelang.org/go/internal/registrytest"
 	"cuelang.org/go/mod/modregistry"
+	"cuelang.org/go/mod/modregistrytest"
 	"cuelang.org/go/mod/module"
 )
 
@@ -180,7 +180,7 @@ func txtarContents(fsys fs.FS) ([]byte, error) {
 }
 
 func newRegistry(t *testing.T, fsys fs.FS) ociregistry.Interface {
-	regSrv, err := registrytest.New(fsys, "")
+	regSrv, err := modregistrytest.New(fsys, "")
 	qt.Assert(t, qt.IsNil(err))
 	t.Cleanup(regSrv.Close)
 	regOCI, err := ociclient.New(regSrv.Host(), &ociclient.Options{
diff --git a/mod/modconfig/modconfig_test.go b/mod/modconfig/modconfig_test.go
index 5629ed0ca..1d150b43c 100644
--- a/mod/modconfig/modconfig_test.go
+++ b/mod/modconfig/modconfig_test.go
@@ -26,8 +26,8 @@ import (
 
 	"cuelang.org/go/internal/cueconfig"
 	"cuelang.org/go/internal/cueversion"
-	"cuelang.org/go/internal/registrytest"
 	"cuelang.org/go/mod/modcache"
+	"cuelang.org/go/mod/modregistrytest"
 	"cuelang.org/go/mod/module"
 )
 
@@ -64,11 +64,11 @@ package x
 	qt.Assert(t, qt.IsNil(err))
 	r1fs, err := fs.Sub(fsys, "r1")
 	qt.Assert(t, qt.IsNil(err))
-	r1, err := registrytest.New(r1fs, "")
+	r1, err := modregistrytest.New(r1fs, "")
 	qt.Assert(t, qt.IsNil(err))
 	r2fs, err := fs.Sub(fsys, "r2")
 	qt.Assert(t, qt.IsNil(err))
-	r2, err := registrytest.New(r2fs, "")
+	r2, err := modregistrytest.New(r2fs, "")
 	qt.Assert(t, qt.IsNil(err))
 
 	dir := t.TempDir()
@@ -147,7 +147,7 @@ package x
 	qt.Assert(t, qt.IsNil(err))
 	ctx := context.Background()
 	rmem := ocimem.NewWithConfig(&ocimem.Config{ImmutableTags: true})
-	err = registrytest.Upload(ctx, rmem, regFS)
+	err = modregistrytest.Upload(ctx, rmem, regFS)
 	qt.Assert(t, qt.IsNil(err))
 	rh := ociserver.New(rmem, nil)
 	agent := cueversion.UserAgent("cuelang.org/go")
@@ -204,7 +204,7 @@ package bar
 		qt.Assert(t, qt.IsNil(err))
 		mux := http.NewServeMux()
 		r := ocimem.New()
-		err = registrytest.Upload(context.Background(), r, fsys)
+		err = modregistrytest.Upload(context.Background(), r, fsys)
 		qt.Assert(t, qt.IsNil(err))
 		rh := ociserver.New(r, nil)
 		mux.HandleFunc("/v2/", func(w http.ResponseWriter, r *http.Request) {
diff --git a/internal/registrytest/fileio.go b/mod/modregistrytest/fileio.go
similarity index 97%
rename from internal/registrytest/fileio.go
rename to mod/modregistrytest/fileio.go
index 3fedc6d16..ffbb82cc7 100644
--- a/internal/registrytest/fileio.go
+++ b/mod/modregistrytest/fileio.go
@@ -1,4 +1,4 @@
-package registrytest
+package modregistrytest
 
 import (
 	"bytes"
diff --git a/internal/registrytest/registry.go b/mod/modregistrytest/registry.go
similarity index 98%
rename from internal/registrytest/registry.go
rename to mod/modregistrytest/registry.go
index e4d8569b2..3ab81e412 100644
--- a/internal/registrytest/registry.go
+++ b/mod/modregistrytest/registry.go
@@ -1,4 +1,9 @@
-package registrytest
+// Package modregistrytest provides helpers for testing packages
+// which interact with CUE registries.
+//
+// WARNING: THIS PACKAGE IS EXPERIMENTAL.
+// ITS API MAY CHANGE AT ANY TIME.
+package modregistrytest
 
 import (
 	"bytes"
diff --git a/internal/registrytest/registry_test.go b/mod/modregistrytest/registry_test.go
similarity index 99%
rename from internal/registrytest/registry_test.go
rename to mod/modregistrytest/registry_test.go
index 26a053428..942fa7bdb 100644
--- a/internal/registrytest/registry_test.go
+++ b/mod/modregistrytest/registry_test.go
@@ -1,4 +1,4 @@
-package registrytest
+package modregistrytest
 
 import (
 	"context"
diff --git a/internal/registrytest/testdata/simple.txtar b/mod/modregistrytest/testdata/simple.txtar
similarity index 100%
rename from internal/registrytest/testdata/simple.txtar
rename to mod/modregistrytest/testdata/simple.txtar