chore: fix lint warning

cmd/oras/internal/display/print.go

@@ -116,7 +116,7 @@ func (p *tagManifestStatusForRepo) PushReference(ctx context.Context, expected o
 	if p.printHint != nil {
 		p.printHint.Do(func() {
 			ref := p.refPrefix + "@" + expected.Digest.String()
-			Print("Tagging", ref)
+			_ = Print("Tagging", ref)
 		})
 	}
 	if err := p.Repository.PushReference(ctx, expected, content, reference); err != nil {
@@ -136,9 +136,10 @@ func (p *tagManifestStatusForTarget) Tag(ctx context.Context, desc ocispec.Descr
 	if p.printHint != nil {
 		p.printHint.Do(func() {
 			ref := p.refPrefix + "@" + desc.Digest.String()
-			Print("Tagging", ref)
+			_ = Print("Tagging", ref)
 		})
 	}
+
 	if err := p.Target.Tag(ctx, desc, reference); err != nil {
 		return err
 	}

cmd/oras/internal/option/applier.go

@@ -29,7 +29,7 @@ type FlagApplier interface {
 // NOTE: The option argument need to be a pointer to the options, so its value
 // becomes addressable.
 func ApplyFlags(optsPtr interface{}, target *pflag.FlagSet) {
-	rangeFields(optsPtr, func(fa FlagApplier) error {
+	_ = rangeFields(optsPtr, func(fa FlagApplier) error {
 		fa.ApplyFlags(target)
 		return nil
 	})

cmd/oras/internal/option/packer_test.go

@@ -70,7 +70,10 @@ func TestPacker_LoadManifestAnnotations_err(t *testing.T) {
 
 func TestPacker_LoadManifestAnnotations_annotationFile(t *testing.T) {
 	testFile := filepath.Join(t.TempDir(), "testAnnotationFile")
-	os.WriteFile(testFile, []byte(testContent), fs.ModePerm)
+	err := os.WriteFile(testFile, []byte(testContent), fs.ModePerm)
+	if err != nil {
+		t.Fatalf("Error writing %s: %v", testFile, err)
+	}
 	opts := Packer{AnnotationFilePath: testFile}
 
 	anno, err := opts.LoadManifestAnnotations()
@@ -120,11 +123,12 @@ func TestPacker_LoadManifestAnnotations_annotationFlag(t *testing.T) {
 		t.Fatalf("unexpected error: failed when looking for '$manifest' in annotations")
 	}
 	if !reflect.DeepEqual(annotations,
-		map[string]map[string]string{"$manifest": {
-			"Key0": "",
-			"Key1": "Val",
-			"Key2": "${env:USERNAME}",
-		},
+		map[string]map[string]string{
+			"$manifest": {
+				"Key0": "",
+				"Key1": "Val",
+				"Key2": "${env:USERNAME}",
+			},
 		}) {
 		t.Fatalf("unexpected error: %v", errors.New("content not match"))
 	}

cmd/oras/internal/option/remote.go

@@ -273,7 +273,9 @@ func (opts *Remote) NewRepository(reference string, common Common) (repo *remote
 		return nil, err
 	}
 	if opts.distributionSpec.referrersAPI != nil {
-		repo.SetReferrersCapability(*opts.distributionSpec.referrersAPI)
+		if err := repo.SetReferrersCapability(*opts.distributionSpec.referrersAPI); err != nil {
+			return nil, err
+		}
 	}
 	return
 }

cmd/oras/internal/option/remote_test.go

@@ -51,7 +51,9 @@ func TestMain(m *testing.M) {
 		case p == "/v2/" && m == "GET":
 			w.WriteHeader(http.StatusOK)
 		case p == fmt.Sprintf("/v2/%s/tags/list", testRepo) && m == "GET":
-			json.NewEncoder(w).Encode(testTagList)
+			if err := json.NewEncoder(w).Encode(testTagList); err != nil {
+				http.Error(w, "error encoding", http.StatusBadRequest)
+			}
 		}
 	}))
 	defer ts.Close()
@@ -233,7 +235,10 @@ func TestRemote_NewRepository_Retry(t *testing.T) {
 			http.Error(w, "error", http.StatusTooManyRequests)
 			return
 		}
-		json.NewEncoder(w).Encode(testTagList)
+		err := json.NewEncoder(w).Encode(testTagList)
+		if err != nil {
+			http.Error(w, "error encoding", http.StatusBadRequest)
+		}
 	}))
 	defer ts.Close()
 	opts := struct {

cmd/oras/root/attach.go

@@ -94,7 +94,7 @@ Example - Attach file to the manifest tagged 'v1' in an OCI image layout folder
 
 	cmd.Flags().StringVarP(&opts.artifactType, "artifact-type", "", "", "artifact type")
 	cmd.Flags().IntVarP(&opts.concurrency, "concurrency", "", 5, "concurrency level")
-	cmd.MarkFlagRequired("artifact-type")
+	_ = cmd.MarkFlagRequired("artifact-type")
 	opts.EnableDistributionSpecFlag()
 	option.ApplyFlags(&opts, cmd.Flags())
 	return cmd

cmd/oras/root/discover.go

@@ -133,7 +133,7 @@ func runDiscover(ctx context.Context, opts discoverOptions) error {
 	fmt.Println("Digest:", desc.Digest)
 	if len(refs) > 0 {
 		fmt.Println()
-		printDiscoveredReferrersTable(refs, opts.Verbose)
+		_ = printDiscoveredReferrersTable(refs, opts.Verbose)
 	}
 	return nil
 }
@@ -171,7 +171,7 @@ func fetchAllReferrers(ctx context.Context, repo oras.ReadOnlyGraphTarget, desc
 	return nil
 }
 
-func printDiscoveredReferrersTable(refs []ocispec.Descriptor, verbose bool) {
+func printDiscoveredReferrersTable(refs []ocispec.Descriptor, verbose bool) error {
 	typeNameTitle := "Artifact Type"
 	typeNameLength := len(typeNameTitle)
 	for _, ref := range refs {
@@ -188,9 +188,12 @@ func printDiscoveredReferrersTable(refs []ocispec.Descriptor, verbose bool) {
 	for _, ref := range refs {
 		print(ref.ArtifactType, ref.Digest)
 		if verbose {
-			printJSON(ref)
+			if err := printJSON(ref); err != nil {
+				return fmt.Errorf("Error printing JSON: %w", err)
+			}
 		}
 	}
+	return nil
 }
 
 // printDiscoveredReferrersJSON prints referrer list in JSON equivalent to the

internal/cache/target_test.go

@@ -177,7 +177,9 @@ func TestProxy_fetchReference(t *testing.T) {
 			w.WriteHeader(http.StatusOK)
 			// write data to the response if this is the first request
 			if requestCount == 1 {
-				w.Write(blob)
+				if _, err := w.Write(blob); err != nil {
+					t.Errorf("Error writing blobs: %v", err)
+				}
 			}
 			atomic.AddInt64(&successCount, 1)
 			return

internal/graph/graph_test.go

@@ -121,7 +121,7 @@ func TestReferrers(t *testing.T) {
 		index
 	)
 	anno := map[string]string{"test": "foo"}
-	appendBlob(ocispec.MediaTypeArtifactManifest, []byte("subject content"))
+	appendBlob(ocispec.MediaTypeArtifactManifest, []byte(`{"name":"subject content"}`))
 	imageType := "test.image"
 	appendBlob(imageType, []byte("config content"))
 	generateImage(nil, nil, descs[imgConfig], descs[blob])
@@ -139,7 +139,9 @@ func TestReferrers(t *testing.T) {
 	referrers := []ocispec.Descriptor{descs[image], descs[image]}
 	memory := memory.New()
 	for i := range descs {
-		memory.Push(ctx, descs[i], bytes.NewReader(blobs[i]))
+		if err := memory.Push(ctx, descs[i], bytes.NewReader(blobs[i])); err != nil {
+			t.Errorf("Error pushing %v\n", err)
+		}
 	}
 	finder := &predecessorFinder{Store: memory}
 
@@ -244,7 +246,7 @@ func TestSuccessors(t *testing.T) {
 		artifact
 		index
 	)
-	appendBlob(ocispec.MediaTypeArtifactManifest, []byte("subject content"))
+	appendBlob(ocispec.MediaTypeArtifactManifest, []byte(`{"name":"subject content"}`))
 	imageType := "test.image"
 	appendBlob(imageType, []byte("config content"))
 	generateImage(&descs[subject], ocispec.MediaTypeImageManifest, descs[config])
@@ -255,7 +257,9 @@ func TestSuccessors(t *testing.T) {
 	memory := memory.New()
 	ctx := context.Background()
 	for i := range descs {
-		memory.Push(ctx, descs[i], bytes.NewReader(blobs[i]))
+		if err := memory.Push(ctx, descs[i], bytes.NewReader(blobs[i])); err != nil {
+			t.Errorf("Error pushing %v\n", err)
+		}
 	}
 	fetcher := &fetcher{Fetcher: memory}
 
@@ -341,7 +345,7 @@ func TestFindReferrerPredecessors(t *testing.T) {
 		image
 	)
 	var anno map[string]string
-	appendBlob(ocispec.MediaTypeArtifactManifest, []byte("subject content"))
+	appendBlob(ocispec.MediaTypeArtifactManifest, []byte(`{"name":"subject content"}`))
 	imageType := "test.image"
 	appendBlob(imageType, []byte("config content"))
 	generateImage(&descs[subject], anno, descs[imgConfig])
@@ -353,7 +357,9 @@ func TestFindReferrerPredecessors(t *testing.T) {
 	referrers := []ocispec.Descriptor{descs[image], descs[image]}
 	memory := memory.New()
 	for i := range descs {
-		memory.Push(ctx, descs[i], bytes.NewReader(blobs[i]))
+		if err := memory.Push(ctx, descs[i], bytes.NewReader(blobs[i])); err != nil {
+			t.Errorf("Error pushing %v\n", err)
+		}
 	}
 	finder := &predecessorFinder{Store: memory}
 	type args struct {
@@ -367,7 +373,6 @@ func TestFindReferrerPredecessors(t *testing.T) {
 		want    []ocispec.Descriptor
 		wantErr bool
 	}{
-
 		{"should failed to get referrers", args{ctx, &errLister{}, ocispec.Descriptor{}}, nil, true},
 		{"should failed to get predecessor", args{ctx, &errFinder{}, ocispec.Descriptor{}}, nil, true},
 		{"should return referrers when target is a referrer lister", args{ctx, &refLister{referrers: referrers}, ocispec.Descriptor{}}, referrers, false},