refactor: apply metadata render interface to index commands

cmd/oras/internal/display/metadata/discard.go

@@ -46,7 +46,5 @@ func (Discard) OnTagged(ocispec.Descriptor, string) error {
 	return nil
 }
 
-// OnCompleted implements ManifestIndexCreateHandler.
-func (Discard) OnCompleted(ocispec.Descriptor) error {
-	return nil
-}
+// OnIndexCreated implements ManifestIndexCreateHandler.
+func (Discard) OnIndexCreated(ocispec.Descriptor) {}

cmd/oras/internal/display/metadata/interface.go

@@ -93,7 +93,9 @@ type ManifestPushHandler interface {
 // ManifestIndexCreateHandler handles metadata output for index create events.
 type ManifestIndexCreateHandler interface {
 	TaggedHandler
-	OnCompleted(desc ocispec.Descriptor) error
+	Renderer
+
+	OnIndexCreated(desc ocispec.Descriptor)
 }
 
 // ManifestIndexUpdateHandler handles metadata output for index update events.

cmd/oras/internal/display/metadata/text/manifest_index.go

@@ -24,6 +24,7 @@ import (
 // ManifestIndexCreateHandler handles text metadata output for index create events.
 type ManifestIndexCreateHandler struct {
 	printer *output.Printer
+	root    ocispec.Descriptor
 }
 
 // NewManifestIndexCreateHandler returns a new handler for index create events.
@@ -38,7 +39,12 @@ func (h *ManifestIndexCreateHandler) OnTagged(_ ocispec.Descriptor, tag string)
 	return h.printer.Println("Tagged", tag)
 }
 
-// OnCompleted implements ManifestIndexCreateHandler.
-func (h *ManifestIndexCreateHandler) OnCompleted(desc ocispec.Descriptor) error {
-	return h.printer.Println("Digest:", desc.Digest)
+// OnIndexCreated implements ManifestIndexCreateHandler.
+func (h *ManifestIndexCreateHandler) OnIndexCreated(desc ocispec.Descriptor) {
+	h.root = desc
+}
+
+// Render implements ManifestIndexCreateHandler.
+func (h *ManifestIndexCreateHandler) Render() error {
+	return h.printer.Println("Digest:", h.root.Digest)
 }

cmd/oras/internal/display/metadata/text/push_test.go

@@ -34,7 +34,7 @@ func (w *errorWriter) Write(p []byte) (n int, err error) {
 	return 0, fmt.Errorf("got an error")
 }
 
-func TestPushHandler_OnCompleted(t *testing.T) {
+func TestPushHandler_Render(t *testing.T) {
 	content := []byte("content")
 	tests := []struct {
 		name    string
@@ -71,7 +71,7 @@ func TestPushHandler_OnCompleted(t *testing.T) {
 				root:    tt.root,
 			}
 			if err := p.Render(); (err != nil) != tt.wantErr {
-				t.Errorf("PushHandler.OnCompleted() error = %v, wantErr %v", err, tt.wantErr)
+				t.Errorf("PushHandler.Render() error = %v, wantErr %v", err, tt.wantErr)
 			}
 		})
 	}

cmd/oras/root/manifest/index/create.go

@@ -140,7 +140,8 @@ func createIndex(cmd *cobra.Command, opts createOptions) error {
 			return err
 		}
 	}
-	return displayMetadata.OnCompleted(desc)
+	displayMetadata.OnIndexCreated(desc)
+	return displayMetadata.Render()
 }
 
 func fetchSourceManifests(ctx context.Context, displayStatus status.ManifestIndexCreateHandler, target oras.ReadOnlyTarget, sources []string) ([]ocispec.Descriptor, error) {

cmd/oras/root/manifest/index/update.go

@@ -148,7 +148,8 @@ func updateIndex(cmd *cobra.Command, opts updateOptions) error {
 			return err
 		}
 	}
-	return displayMetadata.OnCompleted(desc)
+	displayMetadata.OnIndexCreated(desc)
+	return displayMetadata.Render()
 }
 
 func fetchIndex(ctx context.Context, handler status.ManifestIndexUpdateHandler, target oras.ReadOnlyTarget, reference string) (ocispec.Index, error) {