test: add demo command

Signed-off-by: Billy Zha <[email protected]>

cmd/oras/root/cmd.go

@@ -41,6 +41,7 @@ func New() *cobra.Command {
 		blob.Cmd(),
 		manifest.Cmd(),
 		repo.Cmd(),
+		demoCmd(),
 	)
 	return cmd
 }

cmd/oras/root/demo.go

@@ -0,0 +1,67 @@
+/*
+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 root
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+type demoOptions struct {
+	pairs map[string]string
+	slice []string
+	tuple []string
+}
+
+func demoCmd() *cobra.Command {
+	var demoOptions demoOptions
+	cmd := &cobra.Command{
+		Use:   "demo",
+		Short: "Demo of flags",
+		Args: func(cmd *cobra.Command, args []string) error {
+			for i, arg := range args {
+				fmt.Fprintf(os.Stderr, "[%d]: %s\n", i, arg)
+			}
+			return nil
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runDemo(&demoOptions)
+		},
+	}
+
+	cmd.Flags().StringToStringVarP(&demoOptions.pairs, "paired", "p", nil, "paired key-value pairs")
+	cmd.Flags().StringSliceVarP(&demoOptions.slice, "slice", "s", []string{}, "Add a slice of values")
+	cmd.Flags().StringArrayVarP(&demoOptions.tuple, "tuple", "t", []string{}, "Add a tuple of values")
+	return cmd
+}
+
+func runDemo(o *demoOptions) error {
+	fmt.Println("Key-value pairs:")
+	for k, v := range o.pairs {
+		fmt.Printf("> %s: %s\n", k, v)
+	}
+	fmt.Println("Slices:")
+	for i, t := range o.slice {
+		fmt.Printf("> [%d]: %s\n", i, t)
+	}
+	fmt.Println("Tuples:")
+	for i, t := range o.tuple {
+		fmt.Printf("> [%d]: %s\n", i, t)
+	}
+	return nil
+}