Address copilot review comments

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

Author: aravindtga

thirdparty/cmdconfig/commands/cmdcat/cmdcat.go

@@ -1,4 +1,4 @@
-// Copyright 2019-2026 The Kpt Authors.
+// Copyright 2019-2026 The kpt Authors.
 // SPDX-License-Identifier: Apache-2.0
 
 package cmdcat
@@ -14,6 +14,7 @@ import (
 
 	"github.com/kptdev/kpt/internal/docs/generated/pkgdocs"
 	kptfilev1 "github.com/kptdev/kpt/pkg/api/kptfile/v1"
+	"github.com/kptdev/kpt/pkg/printer"
 	"github.com/kptdev/kpt/thirdparty/cmdconfig/commands/runner"
 	"github.com/spf13/cobra"
 	"sigs.k8s.io/kustomize/kyaml/kio"
@@ -24,8 +25,7 @@ import (
 // GetCatRunner returns a command CatRunner.
 func GetCatRunner(ctx context.Context, _ string) *CatRunner {
 	r := &CatRunner{
-		Ctx:       ctx,
-		errWriter: os.Stderr,
+		Ctx: ctx,
 	}
 	c := &cobra.Command{
 		Use:     "cat [FILE | DIR]",
@@ -63,7 +63,6 @@ type CatRunner struct {
 	Styles             []string
 	StripComments      bool
 	RecurseSubPackages bool
-	errWriter          io.Writer
 }
 
 func (r *CatRunner) runE(c *cobra.Command, args []string) error {
@@ -76,6 +75,9 @@ func (r *CatRunner) runE(c *cobra.Command, args []string) error {
 		switch strings.ToLower(filepath.Ext(args[0])) {
 		case ".yaml", ".yml", ".json":
 		default:
+			if filepath.Base(args[0]) == kptfilev1.KptFileName {
+				return fmt.Errorf("%q is a %s package metadata file, not a resource file; no resources will be read", args[0], kptfilev1.KptFileName)
+			}
 			return fmt.Errorf("%q is not a YAML/JSON file; no resources will be read", args[0])
 		}
 	}
@@ -114,7 +116,8 @@ func (r *CatRunner) ExecuteCmd(w io.Writer, pkgPath string) error {
 	if err != nil {
 		// Emit a contextual diagnostic on stderr so the user knows which
 		// package failed; the runner currently aborts on the first error.
-		fmt.Fprintf(r.errWriter, "kpt pkg cat: %s in package %q\n", err.Error(), pkgPath)
+		fmt.Fprintf(printer.FromContextOrDie(r.Ctx).ErrStream(),
+			"kpt pkg cat: %s in package %q\n", err.Error(), pkgPath)
 		return err
 	}
 	fmt.Fprint(w, out.String())

thirdparty/cmdconfig/commands/cmdcat/cmdcat_test.go

@@ -6,11 +6,13 @@ package cmdcat
 import (
 	"bytes"
 	"context"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 
+	"github.com/kptdev/kpt/pkg/printer"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -28,7 +30,8 @@ func writeFile(t *testing.T, path, content string) {
 func runCat(t *testing.T, args ...string) (string, error) {
 	t.Helper()
 	b := &bytes.Buffer{}
-	r := GetCatRunner(context.Background(), "")
+	ctx := printer.WithContext(context.Background(), printer.New(nil, io.Discard))
+	r := GetCatRunner(ctx, "")
 	r.Command.SetArgs(args)
 	r.Command.SetOut(b)
 	r.Command.SetErr(&bytes.Buffer{})
@@ -323,11 +326,18 @@ metadata:
 	for _, arg := range []string{d, d + "/", "./" + filepath.Base(d)} {
 		t.Run(arg, func(t *testing.T) {
 			// Run from d's parent so "./<name>" resolves.
-			oldWd, _ := os.Getwd()
+			oldWd, err := os.Getwd()
+			if err != nil {
+				t.Fatal(err)
+			}
 			if err := os.Chdir(filepath.Dir(d)); err != nil {
 				t.Fatal(err)
 			}
-			defer os.Chdir(oldWd)
+			defer func() {
+				if err := os.Chdir(oldWd); err != nil {
+					t.Fatal(err)
+				}
+			}()
 
 			got, err := runCat(t, arg)
 			assert.NoError(t, err)
@@ -389,10 +399,12 @@ data:
 	assert.Error(t, err)
 	assert.Contains(t, err.Error(), "broken.yaml")
 
-	// Stderr must carry the contextual diagnostic.
+	// Stderr must carry the contextual diagnostic. Inject a printer via
+	// context (mirroring how run.go wires the root cobra err stream) and
+	// assert on its err stream.
 	var errBuf bytes.Buffer
-	r := GetCatRunner(context.Background(), "")
-	r.errWriter = &errBuf
+	ctx := printer.WithContext(context.Background(), printer.New(nil, &errBuf))
+	r := GetCatRunner(ctx, "")
 	r.Command.SetArgs([]string{d})
 	r.Command.SetOut(&bytes.Buffer{})
 	r.Command.SetErr(&bytes.Buffer{})
@@ -422,7 +434,8 @@ metadata:
 `)
 	_, err := runCat(t, kpt)
 	assert.Error(t, err)
-	assert.Contains(t, err.Error(), "not a YAML/JSON file")
+	assert.Contains(t, err.Error(), "Kptfile")
+	assert.Contains(t, err.Error(), "metadata")
 }
 
 // TestCmd_NonYAMLFileErrors: a regular non-YAML/JSON/Kptfile file must