diff --git a/cmd/oras/internal/output/json_test.go b/cmd/oras/internal/output/json_test.go
new file mode 100644
index 000000000..93b7ea2d6
--- /dev/null
+++ b/cmd/oras/internal/output/json_test.go
@@ -0,0 +1,110 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package output
+
+import (
+	"strings"
+	"testing"
+)
+
+func Test_PrintPrettyJSON(t *testing.T) {
+	builder := &strings.Builder{}
+	given := map[string]int{"bob": 5}
+	expected := "{\n  \"bob\": 5\n}\n"
+	err := PrintPrettyJSON(builder, given)
+	if err != nil {
+		t.Error("Expected no error got <" + err.Error() + ">")
+	}
+	actual := builder.String()
+	if expected != actual {
+		t.Error("Expected <" + expected + "> not equal to actual <" + actual + ">")
+	}
+}
+
+func Test_PrintJSON(t *testing.T) {
+	builder := &strings.Builder{}
+	given := []byte("{\"bob\":5}")
+	expected := "{\n  \"bob\": 5\n}\n"
+	err := PrintJSON(builder, given, true)
+	if err != nil {
+		t.Error("Expected no error got <" + err.Error() + ">")
+	}
+	actual := builder.String()
+	if expected != actual {
+		t.Error("Expected <" + expected + "> not equal to actual <" + actual + ">")
+	}
+}
+
+func Test_PrintJSON_ugly(t *testing.T) {
+	builder := &strings.Builder{}
+	given := []byte("{\"bob\":5}")
+	expected := "{\"bob\":5}"
+	err := PrintJSON(builder, given, false)
+	if err != nil {
+		t.Error("Expected no error got <" + err.Error() + ">")
+	}
+	actual := builder.String()
+	if expected != actual {
+		t.Error("Expected <" + expected + "> not equal to actual <" + actual + ">")
+	}
+}
+
+func Test_ToMap(t *testing.T) {
+	type test struct {
+		Name   string `json:"name"`
+		Number int    `json:"number"`
+	}
+	given := test{Name: "bob", Number: 5}
+	actual, err := ToMap(given)
+	if err != nil {
+		t.Error("Expected no error got <" + err.Error() + ">")
+	}
+	value, ok := actual["name"]
+	if ok == false {
+		t.Errorf("Expected key name does not exist %v", actual)
+	}
+	if value != "bob" {
+		t.Errorf("Expected value bob not equal to actual %v", value)
+	}
+	value, ok = actual["number"]
+	if ok == false {
+		t.Errorf("Expected key number does not exist %v", actual)
+	}
+	if value != 5.0 {
+		t.Errorf("Expected value 5 not equal to actual %v", value)
+	}
+	for k := range actual {
+		switch k {
+		case "name":
+		case "number":
+		default:
+			t.Error("Expected key name or number not equal to actual <" + k + ">")
+		}
+	}
+}
+
+func Test_ToMap_error(t *testing.T) {
+	type testError struct {
+		Name  string     `json:"name"`
+		Cycle *testError `json:"cycle"`
+	}
+	given := testError{Name: "bob"}
+	given.Cycle = &given
+	_, err := ToMap(given)
+	if err == nil {
+		t.Error("Expected error")
+	}
+}