Silence Cobra usage on errors

mislav · mislav · commit a6e61a3a8d49 · 2019-10-31T13:47:10.000+01:00
When an error occurs anywhere in a command, Cobra used to print the
error itself and command usage help.

We already print error in `main()`, and we don't want to use command
usage string on anything other than flag-parsing errors.

This also fixes the double output of each error.
diff --git a/command/root.go b/command/root.go
@@ -1,6 +1,7 @@
 package command
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -16,17 +17,24 @@ func init() {
 	RootCmd.PersistentFlags().StringP("current-branch", "B", "", "current git branch")
 	// TODO:
 	// RootCmd.PersistentFlags().BoolP("verbose", "V", false, "enable verbose output")
+
+	RootCmd.SetFlagErrorFunc(func(cmd *cobra.Command, err error) error {
+		cmd.Println(err)
+		cmd.Println(cmd.UsageString())
+		return SilentErr
+	})
 }
 
+var SilentErr = errors.New("SilentErr")
+
 // RootCmd is the entry point of command-line execution
 var RootCmd = &cobra.Command{
 	Use:   "gh",
 	Short: "GitHub CLI",
 	Long:  `Do things with GitHub from your terminal`,
-	Args:  cobra.MinimumNArgs(1),
-	Run: func(cmd *cobra.Command, args []string) {
-		fmt.Println("root")
-	},
+
+	SilenceErrors: true,
+	SilenceUsage:  true,
 }
 
 // overriden in tests
diff --git a/main.go b/main.go
@@ -9,7 +9,9 @@ import (
 
 func main() {
 	if err := command.RootCmd.Execute(); err != nil {
-		fmt.Println(err)
+		if err != command.SilentErr {
+			fmt.Println(err)
+		}
 		os.Exit(1)
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -9,7 +9,9 @@ import (`
`9`	`9`
`10`	`10`	`func main() {`
`11`	`11`	`if err := command.RootCmd.Execute(); err != nil {`
`12`		`- fmt.Println(err)`
	`12`	`+ if err != command.SilentErr {`
	`13`	`+ fmt.Println(err)`
	`14`	`+ }`
`13`	`15`	`os.Exit(1)`
`14`	`16`	`}`
`15`	`17`	`}`