feat(comp): Add descriptions for output format

Ref: HIP 0008

When completing output formats, extra information will be shown
for shells that support completions (fish, zsh).  For example:

$ helm status -o <TAB>
json   -- Output result in JSON format
table  -- Output result in human-readable format
yaml   -- Output result in YAML format

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

cmd/helm/flags.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"log"
 	"path/filepath"
+	"sort"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -66,11 +67,14 @@ func bindOutputFlag(cmd *cobra.Command, varRef *output.Format) {
 
 	err := cmd.RegisterFlagCompletionFunc(outputFlag, func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		var formatNames []string
-		for _, format := range output.Formats() {
+		for format, desc := range output.FormatsWithDesc() {
 			if strings.HasPrefix(format, toComplete) {
-				formatNames = append(formatNames, format)
+				formatNames = append(formatNames, fmt.Sprintf("%s\t%s", format, desc))
 			}
 		}
+
+		// Sort the results to get a deterministic order for the tests
+		sort.Strings(formatNames)
 		return formatNames, cobra.ShellCompDirectiveNoFileComp
 	})
 

cmd/helm/testdata/output/output-comp.txt

@@ -1,5 +1,5 @@
-table
-json
-yaml
+json	Output result in JSON format
+table	Output result in human-readable format
+yaml	Output result in YAML format
 :4
 Completion ended with directive: ShellCompDirectiveNoFileComp

pkg/cli/output/output.go

@@ -40,6 +40,16 @@ func Formats() []string {
 	return []string{Table.String(), JSON.String(), YAML.String()}
 }
 
+// FormatsWithDesc returns a list of the string representation of the supported formats
+// including a description
+func FormatsWithDesc() map[string]string {
+	return map[string]string{
+		Table.String(): "Output result in human-readable format",
+		JSON.String():  "Output result in JSON format",
+		YAML.String():  "Output result in YAML format",
+	}
+}
+
 // ErrInvalidFormatType is returned when an unsupported format type is used
 var ErrInvalidFormatType = fmt.Errorf("invalid format type")