internal/registrytest: support prefix

This will allow the cue command tests to test against modules
stored at an arbitrary prefix in the OCI registry.

For #2330.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I82b3a9026774189d8cc38bf0d109ef0e5daa507a
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1170244
Unity-Result: CUE porcuepine <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

Author: rogpeppe

cue/load/module_test.go

@@ -17,7 +17,7 @@ func TestModuleFetch(t *testing.T) {
 		Name: "modfetch",
 	}
 	test.Run(t, func(t *cuetxtar.Test) {
-		r, err := registrytest.New(registrytest.TxtarFS(t.Archive))
+		r, err := registrytest.New(registrytest.TxtarFS(t.Archive), "")
 		if err != nil {
 			t.Fatal(err)
 		}

internal/registrytest/registry.go

@@ -11,6 +11,7 @@ import (
 	"net/url"
 	"strings"
 
+	"cuelabs.dev/go/oci/ociregistry/ocifilter"
 	"cuelabs.dev/go/oci/ociregistry/ocimem"
 	"cuelabs.dev/go/oci/ociregistry/ociserver"
 	"golang.org/x/tools/txtar"
@@ -25,18 +26,21 @@ import (
 
 // New starts a registry instance that serves modules found inside the
 // _registry path inside fsys. It serves the OCI registry protocol.
+// If prefix is non-empty, all module paths will be prefixed by that,
+// separated by a slash (/).
 //
 // Each module should be inside a directory named path_vers, where
 // slashes in path have been replaced with underscores and should
 // contain a cue.mod/module.cue file holding the module info.
 //
 // The Registry should be closed after use.
-func New(fsys fs.FS) (*Registry, error) {
+func New(fsys fs.FS, prefix string) (*Registry, error) {
 	r := ocimem.New()
-	client, err := modregistry.NewClient(r)
+	client, err := modregistry.NewClient(ocifilter.Sub(r, prefix))
 	if err != nil {
 		return nil, fmt.Errorf("cannot make client: %v", err)
 	}
+
 	mods, err := getModules(fsys)
 	if err != nil {
 		return nil, fmt.Errorf("invalid modules: %v", err)

internal/registrytest/registry_test.go

@@ -11,6 +11,7 @@ import (
 
 	"cuelabs.dev/go/oci/ociregistry"
 	"cuelabs.dev/go/oci/ociregistry/ociclient"
+	"cuelabs.dev/go/oci/ociregistry/ocifilter"
 	"golang.org/x/tools/txtar"
 
 	"cuelang.org/go/internal/mod/modregistry"
@@ -34,15 +35,15 @@ func TestRegistry(t *testing.T) {
 			t.Fatal(err)
 		}
 		t.Run(strings.TrimSuffix(name, ".txtar"), func(t *testing.T) {
-			r, err := New(TxtarFS(ar))
+			r, err := New(TxtarFS(ar), "someprefix/other")
 			if err != nil {
 				t.Fatal(err)
 			}
 			defer r.Close()
 			client, err := ociclient.New(r.Host(), &ociclient.Options{
 				Insecure: true,
 			})
-			runTest(t, client, string(ar.Comment), ar)
+			runTest(t, ocifilter.Sub(client, "someprefix/other"), string(ar.Comment), ar)
 		})
 	}
 }