Fix misleading error message when verb is bad (#589)

* validate sub command verb (#557)

* fix review comments for pr #555

* validate sub commands

* update error message

* use inner args returned by find func

* return appropriate error message for #557

* return appropriate error message for #557

* Revert "fix review comments for pr #555"

This reverts commit 14ea8d2.

* review comments for pr 589

* misleading error message when verb is bad (#557)

* misleading error message when verb is bad (#557)

* misleading error message when verb is bad (#557)

pkg/kn/core/root.go

@@ -72,18 +72,22 @@ func NewDefaultKnCommandWithArgs(rootCmd *cobra.Command,
 	if pluginHandler == nil {
 		return rootCmd
 	}
-
 	if len(args) > 1 {
 		cmdPathPieces := args[1:]
 		cmdPathPieces = removeKnPluginFlags(cmdPathPieces) // Plugin does not need these flags
 
 		// only look for suitable extension executables if
 		// the specified command does not already exist
-		if _, _, err := rootCmd.Find(cmdPathPieces); err != nil {
+		foundCmd, innerArgs, err := rootCmd.Find(cmdPathPieces)
+		if err != nil {
 			err := plugin.HandlePluginCommand(pluginHandler, cmdPathPieces)
 			if err != nil {
-				rootCmd.Help()
-				fmt.Fprintf(rootCmd.OutOrStderr(), "Unknown command or plugin '%s'.\n", args[1])
+				fmt.Fprintf(rootCmd.OutOrStderr(), "Error: unknown command '%s' \nRun 'kn --help' for usage.\n", args[1])
+				os.Exit(1)
+			}
+		} else if foundCmd.HasSubCommands() {
+			if _, _, err := rootCmd.Find(innerArgs); err != nil {
+				fmt.Fprintf(rootCmd.OutOrStderr(), showSubcommands(foundCmd, cmdPathPieces, innerArgs[0]))
 				os.Exit(1)
 			}
 		}
@@ -288,3 +292,22 @@ func width() (int, error) {
 	width, _, err := terminal.GetSize(int(os.Stdout.Fd()))
 	return width, err
 }
+
+func getCommands(args []string, innerArg string) string {
+	commands := []string{"kn"}
+	for _, arg := range args {
+		if arg == innerArg {
+			return strings.Join(commands, " ")
+		}
+		commands = append(commands, arg)
+	}
+	return ""
+}
+
+func showSubcommands(cmd *cobra.Command, args []string, innerArg string) string {
+	var strs []string
+	for _, subcmd := range cmd.Commands() {
+		strs = append(strs, subcmd.Name())
+	}
+	return fmt.Sprintf("Error: unknown subcommand '%s' for '%s'. Available subcommands: %s\nRun 'kn --help' for usage.\n", innerArg, getCommands(args, innerArg), strings.Join(strs, ", "))
+}

test/e2e/basic_workflow_test.go

@@ -69,6 +69,10 @@ func TestBasicWorkflow(t *testing.T) {
 	t.Run("return no service after completing tests", func(t *testing.T) {
 		test.serviceListEmpty(t)
 	})
+	t.Run("error out of wrong commands and subcommands", func(t *testing.T) {
+		test.wrongSubCommand(t)
+		test.wrongCommand(t)
+	})
 }
 
 func (test *e2eTest) serviceListEmpty(t *testing.T) {
@@ -136,3 +140,15 @@ func (test *e2eTest) revisionDescribe(t *testing.T, serviceName string) {
 	assert.NilError(t, err)
 	assert.Check(t, util.ContainsAll(out, revName, test.kn.namespace, serviceName, "++ Ready", "TARGET=kn"))
 }
+
+func (test *e2eTest) wrongSubCommand(t *testing.T) {
+
+	_, err := test.kn.RunWithOpts([]string{"source", "apiserver", "noverb", "--tag=0.13"}, runOpts{AllowError: true})
+	assert.ErrorContains(t, err, "Error: unknown subcommand 'noverb' for 'kn source apiserver'. Available subcommands: create, delete, describe, list, update")
+}
+
+func (test *e2eTest) wrongCommand(t *testing.T) {
+
+	_, err := test.kn.RunWithOpts([]string{"rev"}, runOpts{AllowError: true})
+	assert.ErrorContains(t, err, "Error: unknown command 'rev'", "Run 'kn --help' for usage.")
+}