plugin: Add output format in list command

Added JSON, YAML and Table output format in helm plugin list

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>

CONTRIBUTING.md

@@ -197,7 +197,7 @@ below.
 3. Discussion
     - issues that are labeled as `feature` or `bug` should be connected to the PR that resolves it.
     - Whoever is working on a `feature` or `bug` issue (whether a maintainer or someone from the
-      community), should either assign the issue to themself or make a comment in the issue saying
+      community), should either assign the issue to themselves or make a comment in the issue saying
       that they are taking it.
     - `proposal` and `support/question` issues should stay open until resolved or if they have not
       been active for more than 30 days. This will help keep the issue queue to a manageable size

cmd/helm/plugin_list.go

@@ -16,17 +16,18 @@ limitations under the License.
 package main
 
 import (
-	"fmt"
 	"io"
 	"strings"
 
 	"github.com/gosuri/uitable"
 	"github.com/spf13/cobra"
 
+	"helm.sh/helm/v3/pkg/cli/output"
 	"helm.sh/helm/v3/pkg/plugin"
 )
 
 func newPluginListCmd(out io.Writer) *cobra.Command {
+	var outfmt output.Format
 	cmd := &cobra.Command{
 		Use:     "list",
 		Aliases: []string{"ls"},
@@ -38,16 +39,33 @@ func newPluginListCmd(out io.Writer) *cobra.Command {
 				return err
 			}
 
+			return outfmt.Write(out, &pluginListWriter{plugins})
+		},
+	}
+	bindOutputFlag(cmd, &outfmt)
+
+	return cmd
+}
+
+type pluginListWriter struct {
+	plugins []*plugin.Plugin
+}
+
+func (p *pluginListWriter) WriteTable(out io.Writer) error {
 	table := uitable.New()
 	table.AddRow("NAME", "VERSION", "DESCRIPTION")
-			for _, p := range plugins {
+	for _, p := range p.plugins {
 		table.AddRow(p.Metadata.Name, p.Metadata.Version, p.Metadata.Description)
 	}
-			fmt.Fprintln(out, table)
-			return nil
-		},
+	return output.EncodeTable(out, table)
 }
-	return cmd
+
+func (p *pluginListWriter) WriteJSON(out io.Writer) error {
+	return output.EncodeJSON(out, p.plugins)
+}
+
+func (p *pluginListWriter) WriteYAML(out io.Writer) error {
+	return output.EncodeYAML(out, p.plugins)
 }
 
 // Provide dynamic auto-completion for plugin names

cmd/helm/plugin_list_test.go

@@ -0,0 +1,42 @@
+/*
+Copyright The Helm 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 main
+
+import (
+	"testing"
+)
+
+func TestPluginListCmd(t *testing.T) {
+	tests := []cmdTestCase{{
+		name:   "List plugins",
+		cmd:    "plugin list",
+		golden: "output/plugin-list.txt",
+	}, {
+		name:   "List plugins with JSON",
+		cmd:    "plugin list -o json",
+		golden: "output/plugin-list-json.txt",
+	}, {
+		name:   "List plugins with YAML",
+		cmd:    "plugin list -o yaml",
+		golden: "output/plugin-list-yaml.txt",
+	}}
+	runTestCmd(t, tests)
+}
+
+func TestPluginListOutputCompletion(t *testing.T) {
+	outputFlagCompletionTest(t, "plugin list")
+}

cmd/helm/testdata/output/plugin-list-json.txt

@@ -0,0 +1 @@
+[]

cmd/helm/testdata/output/plugin-list-yaml.txt

@@ -0,0 +1 @@
+[]

cmd/helm/testdata/output/plugin-list.txt

@@ -0,0 +1 @@
+NAME	VERSION	DESCRIPTION