refactor: add stdout to metadata handlers

cmd/oras/internal/display/handler.go

@@ -16,6 +16,7 @@ limitations under the License.
 package display
 
 import (
+	"io"
 	"os"
 
 	"oras.land/oras/cmd/oras/internal/display/metadata"
@@ -26,7 +27,7 @@ import (
 )
 
 // NewPushHandler returns status and metadata handlers for push command.
-func NewPushHandler(format string, tty *os.File, verbose bool) (status.PushHandler, metadata.PushHandler) {
+func NewPushHandler(format string, tty *os.File, out io.Writer, verbose bool) (status.PushHandler, metadata.PushHandler) {
 	var statusHandler status.PushHandler
 	if tty != nil {
 		statusHandler = status.NewTTYPushHandler(tty)
@@ -39,18 +40,18 @@ func NewPushHandler(format string, tty *os.File, verbose bool) (status.PushHandl
 	var metadataHandler metadata.PushHandler
 	switch format {
 	case "":
-		metadataHandler = text.NewPushHandler()
+		metadataHandler = text.NewPushHandler(out)
 	case "json":
-		metadataHandler = json.NewPushHandler()
+		metadataHandler = json.NewPushHandler(out)
 	default:
-		metadataHandler = template.NewPushHandler(format)
+		metadataHandler = template.NewPushHandler(out, format)
 	}
 
 	return statusHandler, metadataHandler
 }
 
 // NewAttachHandler returns status and metadata handlers for attach command.
-func NewAttachHandler(format string, tty *os.File, verbose bool) (status.AttachHandler, metadata.AttachHandler) {
+func NewAttachHandler(format string, tty *os.File, out io.Writer, verbose bool) (status.AttachHandler, metadata.AttachHandler) {
 	var statusHandler status.AttachHandler
 	if tty != nil {
 		statusHandler = status.NewTTYAttachHandler(tty)
@@ -63,11 +64,11 @@ func NewAttachHandler(format string, tty *os.File, verbose bool) (status.AttachH
 	var metadataHandler metadata.AttachHandler
 	switch format {
 	case "":
-		metadataHandler = text.NewAttachHandler()
+		metadataHandler = text.NewAttachHandler(out)
 	case "json":
-		metadataHandler = json.NewAttachHandler()
+		metadataHandler = json.NewAttachHandler(out)
 	default:
-		metadataHandler = template.NewAttachHandler(format)
+		metadataHandler = template.NewAttachHandler(out, format)
 	}
 
 	return statusHandler, metadataHandler

cmd/oras/internal/display/metadata/json/attach.go

@@ -16,21 +16,27 @@ limitations under the License.
 package json
 
 import (
+	"io"
+
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras/cmd/oras/internal/display/metadata"
 	"oras.land/oras/cmd/oras/internal/display/metadata/model"
 	"oras.land/oras/cmd/oras/internal/option"
 )
 
 // AttachHandler handles json metadata output for attach events.
-type AttachHandler struct{}
+type AttachHandler struct {
+	out io.Writer
+}
 
 // NewAttachHandler creates a new handler for attach events.
-func NewAttachHandler() metadata.AttachHandler {
-	return AttachHandler{}
+func NewAttachHandler(out io.Writer) metadata.AttachHandler {
+	return &AttachHandler{
+		out: out,
+	}
 }
 
 // OnCompleted is called when the attach command is completed.
-func (AttachHandler) OnCompleted(opts *option.Target, root, subject ocispec.Descriptor) error {
-	return printJSON(model.NewPush(root, opts.Path))
+func (ah *AttachHandler) OnCompleted(opts *option.Target, root, subject ocispec.Descriptor) error {
+	return printJSON(ah.out, model.NewPush(root, opts.Path))
 }

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

@@ -17,11 +17,11 @@ package json
 
 import (
 	"encoding/json"
-	"os"
+	"io"
 )
 
-func printJSON(object any) error {
-	encoder := json.NewEncoder(os.Stdout)
+func printJSON(out io.Writer, object any) error {
+	encoder := json.NewEncoder(out)
 	encoder.SetIndent("", "  ")
 	return encoder.Encode(object)
 }

cmd/oras/internal/display/metadata/json/push.go

@@ -16,6 +16,8 @@ limitations under the License.
 package json
 
 import (
+	"io"
+
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras/cmd/oras/internal/display/metadata"
 	"oras.land/oras/cmd/oras/internal/display/metadata/model"
@@ -25,11 +27,14 @@ import (
 // PushHandler handles JSON metadata output for push events.
 type PushHandler struct {
 	path string
+	out  io.Writer
 }
 
 // NewPushHandler creates a new handler for push events.
-func NewPushHandler() metadata.PushHandler {
-	return &PushHandler{}
+func NewPushHandler(out io.Writer) metadata.PushHandler {
+	return &PushHandler{
+		out: out,
+	}
 }
 
 // OnCopied is called after files are copied.
@@ -40,5 +45,5 @@ func (ph *PushHandler) OnCopied(opts *option.Target) error {
 
 // OnCompleted is called after the push is completed.
 func (ph *PushHandler) OnCompleted(root ocispec.Descriptor) error {
-	return printJSON(model.NewPush(root, ph.path))
+	return printJSON(ph.out, model.NewPush(root, ph.path))
 }

cmd/oras/internal/display/metadata/template/attach.go

@@ -16,6 +16,8 @@ limitations under the License.
 package template
 
 import (
+	"io"
+
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras/cmd/oras/internal/display/metadata"
 	"oras.land/oras/cmd/oras/internal/display/metadata/model"
@@ -25,14 +27,18 @@ import (
 // AttachHandler handles go-template metadata output for attach events.
 type AttachHandler struct {
 	template string
+	out      io.Writer
 }
 
 // NewAttachHandler returns a new handler for attach metadata events.
-func NewAttachHandler(template string) metadata.AttachHandler {
-	return &AttachHandler{template: template}
+func NewAttachHandler(out io.Writer, template string) metadata.AttachHandler {
+	return &AttachHandler{
+		out:      out,
+		template: template,
+	}
 }
 
 // OnCompleted formats the metadata of attach command.
 func (ah *AttachHandler) OnCompleted(opts *option.Target, root, subject ocispec.Descriptor) error {
-	return parseAndWrite(model.NewPush(root, opts.Path), ah.template)
+	return parseAndWrite(ah.out, model.NewPush(root, opts.Path), ah.template)
 }

cmd/oras/internal/display/metadata/template/push.go

@@ -16,6 +16,8 @@ limitations under the License.
 package template
 
 import (
+	"io"
+
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras/cmd/oras/internal/display/metadata"
 	"oras.land/oras/cmd/oras/internal/display/metadata/model"
@@ -26,11 +28,15 @@ import (
 type PushHandler struct {
 	template string
 	path     string
+	out      io.Writer
 }
 
 // NewPushHandler returns a new handler for push events.
-func NewPushHandler(template string) metadata.PushHandler {
-	return &PushHandler{template: template}
+func NewPushHandler(out io.Writer, template string) metadata.PushHandler {
+	return &PushHandler{
+		out:      out,
+		template: template,
+	}
 }
 
 // OnStarted is called after files are copied.
@@ -41,5 +47,5 @@ func (ph *PushHandler) OnCopied(opts *option.Target) error {
 
 // OnCompleted is called after the push is completed.
 func (ph *PushHandler) OnCompleted(root ocispec.Descriptor) error {
-	return parseAndWrite(model.NewPush(root, ph.path), ph.template)
+	return parseAndWrite(ph.out, model.NewPush(root, ph.path), ph.template)
 }

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

@@ -16,16 +16,16 @@ limitations under the License.
 package template
 
 import (
-	"os"
+	"io"
 	"text/template"
 
 	"github.com/Masterminds/sprig/v3"
 )
 
-func parseAndWrite(object any, templateStr string) error {
+func parseAndWrite(out io.Writer, object any, templateStr string) error {
 	t, err := template.New("format output").Funcs(sprig.FuncMap()).Parse(templateStr)
 	if err != nil {
 		return err
 	}
-	return t.Execute(os.Stdout, object)
+	return t.Execute(out, object)
 }

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

@@ -17,6 +17,7 @@ package text
 
 import (
 	"fmt"
+	"io"
 	"strings"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -25,23 +26,27 @@ import (
 )
 
 // AttachHandler handles text metadata output for attach events.
-type AttachHandler struct{}
+type AttachHandler struct {
+	out io.Writer
+}
 
 // NewAttachHandler returns a new handler for attach events.
-func NewAttachHandler() metadata.AttachHandler {
-	return AttachHandler{}
+func NewAttachHandler(out io.Writer) metadata.AttachHandler {
+	return &AttachHandler{
+		out: out,
+	}
 }
 
 // OnCompleted is called when the attach command is completed.
-func (AttachHandler) OnCompleted(opts *option.Target, root, subject ocispec.Descriptor) error {
+func (ah *AttachHandler) OnCompleted(opts *option.Target, root, subject ocispec.Descriptor) error {
 	digest := subject.Digest.String()
 	if !strings.HasSuffix(opts.RawReference, digest) {
 		opts.RawReference = fmt.Sprintf("%s@%s", opts.Path, subject.Digest)
 	}
-	_, err := fmt.Println("Attached to", opts.AnnotatedReference())
+	_, err := fmt.Fprintln(ah.out, "Attached to", opts.AnnotatedReference())
 	if err != nil {
 		return err
 	}
-	_, err = fmt.Println("Digest:", root.Digest)
+	_, err = fmt.Fprintln(ah.out, "Digest:", root.Digest)
 	return err
 }

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

@@ -17,28 +17,33 @@ package text
 
 import (
 	"fmt"
+	"io"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras/cmd/oras/internal/display/metadata"
 	"oras.land/oras/cmd/oras/internal/option"
 )
 
 // PushHandler handles text metadata output for push events.
-type PushHandler struct{}
+type PushHandler struct {
+	out io.Writer
+}
 
 // NewPushHandler returns a new handler for push events.
-func NewPushHandler() metadata.PushHandler {
-	return PushHandler{}
+func NewPushHandler(out io.Writer) metadata.PushHandler {
+	return &PushHandler{
+		out: out,
+	}
 }
 
 // OnCopied is called after files are copied.
-func (PushHandler) OnCopied(opts *option.Target) error {
-	_, err := fmt.Println("Pushed", opts.AnnotatedReference())
+func (p *PushHandler) OnCopied(opts *option.Target) error {
+	_, err := fmt.Fprintln(p.out, "Pushed", opts.AnnotatedReference())
 	return err
 }
 
 // OnCompleted is called after the push is completed.
-func (PushHandler) OnCompleted(root ocispec.Descriptor) error {
-	_, err := fmt.Println("Digest:", root.Digest)
+func (p *PushHandler) OnCompleted(root ocispec.Descriptor) error {
+	_, err := fmt.Fprintln(p.out, "Digest:", root.Digest)
 	return err
 }

cmd/oras/root/attach.go

@@ -113,7 +113,7 @@ func runAttach(cmd *cobra.Command, opts *attachOptions) error {
 			Recommendation: `To attach to an existing artifact, please provide files via argument or annotations via flag "--annotation". Run "oras attach -h" for more options and examples`,
 		}
 	}
-	displayStatus, displayMetadata := display.NewAttachHandler(opts.Template, opts.TTY, opts.Verbose)
+	displayStatus, displayMetadata := display.NewAttachHandler(opts.Template, opts.TTY, cmd.OutOrStdout(), opts.Verbose)
 
 	// prepare manifest
 	store, err := file.New("")

cmd/oras/root/push.go

@@ -138,7 +138,7 @@ func runPush(cmd *cobra.Command, opts *pushOptions) error {
 	if err != nil {
 		return err
 	}
-	displayStatus, displayMetadata := display.NewPushHandler(opts.Template, opts.TTY, opts.Verbose)
+	displayStatus, displayMetadata := display.NewPushHandler(opts.Template, opts.TTY, cmd.OutOrStdout(), opts.Verbose)
 
 	// prepare pack
 	packOpts := oras.PackManifestOptions{