diff --git a/attributes/parse.go b/attributes/parse.go
index 102ac096..ea4ffc53 100644
--- a/attributes/parse.go
+++ b/attributes/parse.go
@@ -104,7 +104,7 @@ func trimQuotes(input string) string {
 	return strings.Trim(input, `"`)
 }
 
-// ParseToSet converts a json.RawMessage to an model.AttributeSet.
+// ParseToSet converts a json.RawMessage to a model.AttributeSet.
 func ParseToSet(input json.RawMessage) (model.AttributeSet, error) {
 	set := map[string]model.AttributeValue{}
 
diff --git a/util/testutils/registry.go b/util/testutils/registry.go
deleted file mode 100644
index 31634b6f..00000000
--- a/util/testutils/registry.go
+++ /dev/null
@@ -1,92 +0,0 @@
-package testutils
-
-import (
-	"encoding/json"
-	"net/http"
-	"strings"
-	"testing"
-
-	"github.com/opencontainers/go-digest"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/stretchr/testify/require"
-	"oras.land/oras-go/v2/content"
-)
-
-// NewRegistry returns a handler which implements a mock registry with a v3
-// attributes endpoint.
-func NewRegistry(t *testing.T, blobs [][]byte, manifests [][]byte) http.Handler {
-	blobsByDigest := map[string][]byte{}
-	for _, blob := range blobs {
-		d := digest.FromBytes(blob)
-		blobsByDigest[d.String()] = blob
-	}
-
-	manifestsByDigest := map[string][]byte{}
-	var manifestDescs []ocispec.Descriptor
-	for _, manifest := range manifests {
-		d := digest.FromBytes(manifest)
-		manifestsByDigest[d.String()] = manifest
-		manifestDesc := content.NewDescriptorFromBytes(ocispec.MediaTypeArtifactManifest, manifest)
-		manifestDescs = append(manifestDescs, manifestDesc)
-	}
-
-	testIndex := ocispec.Index{
-		MediaType: ocispec.MediaTypeImageIndex,
-		Manifests: manifestDescs,
-	}
-	testIndexJSON, err := json.Marshal(testIndex)
-	require.NoError(t, err)
-	d := digest.FromBytes(testIndexJSON)
-	registryFN := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != http.MethodGet {
-			t.Errorf("unexpected access: %s %s", r.Method, r.URL)
-			w.WriteHeader(http.StatusMethodNotAllowed)
-			return
-		}
-		switch {
-		case strings.HasPrefix(r.URL.Path, "/v2/test/blobs/"):
-			parts := strings.Split(r.URL.Path, "/")
-			digest := parts[len(parts)-1]
-			content, ok := blobsByDigest[digest]
-			if !ok {
-				t.Errorf("failed to find blob")
-			}
-			w.Header().Set("Content-Type", "application/octet-stream")
-			w.Header().Set("Docker-Content-Digest", digest)
-			if _, err := w.Write(content); err != nil {
-				t.Errorf("failed to write %q: %v", r.URL, err)
-			}
-		case strings.HasPrefix(r.URL.Path, "/v2/test/manifests/"):
-			if accept := r.Header.Get("Accept"); !strings.Contains(accept, ocispec.MediaTypeImageManifest) {
-				t.Errorf("manifest not convertable: %s", accept)
-				w.WriteHeader(http.StatusBadRequest)
-				return
-			}
-			parts := strings.Split(r.URL.Path, "/")
-			digest := parts[len(parts)-1]
-			content, ok := manifestsByDigest[digest]
-			if !ok {
-				t.Errorf("failed to find blob")
-			}
-			w.Header().Set("Content-Type", ocispec.MediaTypeImageManifest)
-			w.Header().Set("Docker-Content-Digest", digest)
-			if _, err := w.Write(content); err != nil {
-				t.Errorf("failed to write %q: %v", r.URL, err)
-			}
-		case strings.HasPrefix(r.URL.Path, "/v2/attributes"):
-			values := r.URL.Query()
-			if !values.Has("attributes") && !values.Has("digests") && !values.Has("links") {
-				t.Errorf("wrong query type")
-			}
-			w.Header().Set("Content-Type", ocispec.MediaTypeImageIndex)
-			w.Header().Set("Docker-Content-Digest", d.String())
-			if _, err := w.Write(testIndexJSON); err != nil {
-				t.Errorf("failed to write %q: %v", r.URL, err)
-			}
-		default:
-			t.Errorf("unexpected access: %s %s", r.Method, r.URL)
-			w.WriteHeader(http.StatusNotFound)
-		}
-	})
-	return registryFN
-}