Add HideHelpCommand

While `HideHelp` hides both `help` command and `--help` flag, `HideHelpCommand`
only hides `help` command and leave `--help` flag as-is.

The behavior of `HideHelp` is untouched in this commit.

Fix #523
Replace #636

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

app.go

@@ -43,8 +43,11 @@ type App struct {
 	Flags []Flag
 	// Boolean to enable bash completion commands
 	EnableBashCompletion bool
-	// Boolean to hide built-in help command
+	// Boolean to hide built-in help command and help flag
 	HideHelp bool
+	// Boolean to hide built-in help command but keep help flag.
+	// Ignored if HideHelp is true.
+	HideHelpCommand bool
 	// Boolean to hide built-in version flag and the VERSION section of help
 	HideVersion bool
 	// categories contains the categorized commands and is populated on app startup
@@ -170,7 +173,9 @@ func (a *App) Setup() {
 	a.Commands = newCommands
 
 	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
+		if !a.HideHelpCommand {
 			a.appendCommand(helpCommand)
+		}
 
 		if HelpFlag != nil {
 			a.appendFlag(HelpFlag)
@@ -328,19 +333,9 @@ func (a *App) RunAndExitOnError() {
 // RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to
 // generate command-specific flags
 func (a *App) RunAsSubcommand(ctx *Context) (err error) {
+	// Setup also handles HideHelp and HideHelpCommand
 	a.Setup()
 
-	// append help to commands
-	if len(a.Commands) > 0 {
-		if a.Command(helpCommand.Name) == nil && !a.HideHelp {
-			a.appendCommand(helpCommand)
-
-			if HelpFlag != nil {
-				a.appendFlag(HelpFlag)
-			}
-		}
-	}
-
 	var newCmds []*Command
 	for _, c := range a.Commands {
 		if c.HelpName == "" {

command.go

@@ -41,8 +41,11 @@ type Command struct {
 	Flags []Flag
 	// Treat all flags as normal arguments if true
 	SkipFlagParsing bool
-	// Boolean to hide built-in help command
+	// Boolean to hide built-in help command and help flag
 	HideHelp bool
+	// Boolean to hide built-in help command but keep help flag
+	// Ignored if HideHelp is true.
+	HideHelpCommand bool
 	// Boolean to hide this command from help or completion
 	Hidden bool
 	// Boolean to enable short-option handling so user can combine several
@@ -236,6 +239,7 @@ func (c *Command) startApp(ctx *Context) error {
 	app.Commands = c.Subcommands
 	app.Flags = c.Flags
 	app.HideHelp = c.HideHelp
+	app.HideHelpCommand = c.HideHelpCommand
 
 	app.Version = ctx.App.Version
 	app.HideVersion = ctx.App.HideVersion

flag.go

@@ -36,7 +36,7 @@ var VersionFlag Flag = &BoolFlag{
 
 // HelpFlag prints the help for all commands and subcommands.
 // Set to nil to disable the flag.  The subcommand
-// will still be added unless HideHelp is set to true.
+// will still be added unless HideHelp or HideHelpCommand is set to true.
 var HelpFlag Flag = &BoolFlag{
 	Name:    "help",
 	Aliases: []string{"h"},

help_test.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"runtime"
 	"strings"
 	"testing"
@@ -762,3 +763,147 @@ VERSION:
 		t.Errorf("expected output to include \"VERSION:, 2.0.0\"; got: %q", output.String())
 	}
 }
+
+func TestHideHelpCommand(t *testing.T) {
+	app := &App{
+		HideHelpCommand: true,
+		Writer:          ioutil.Discard,
+	}
+
+	err := app.Run([]string{"foo", "help"})
+	if err == nil {
+		t.Fatalf("expected a non-nil error")
+	}
+	if !strings.Contains(err.Error(), "No help topic for 'help'") {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.Run([]string{"foo", "--help"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestHideHelpCommand_False(t *testing.T) {
+	app := &App{
+		HideHelpCommand: false,
+		Writer:          ioutil.Discard,
+	}
+
+	err := app.Run([]string{"foo", "help"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.Run([]string{"foo", "--help"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestHideHelpCommand_WithHideHelp(t *testing.T) {
+	app := &App{
+		HideHelp:        true, // effective (hides both command and flag)
+		HideHelpCommand: true, // ignored
+		Writer:          ioutil.Discard,
+	}
+
+	err := app.Run([]string{"foo", "help"})
+	if err == nil {
+		t.Fatalf("expected a non-nil error")
+	}
+	if !strings.Contains(err.Error(), "No help topic for 'help'") {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.Run([]string{"foo", "--help"})
+	if err == nil {
+		t.Fatalf("expected a non-nil error")
+	}
+	if !strings.Contains(err.Error(), "flag: help requested") {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func newContextFromStringSlice(ss []string) *Context {
+	set := flag.NewFlagSet("", flag.ContinueOnError)
+	_ = set.Parse(ss)
+	return &Context{flagSet: set}
+}
+
+func TestHideHelpCommand_RunAsSubcommand(t *testing.T) {
+	app := &App{
+		HideHelpCommand: true,
+		Writer:          ioutil.Discard,
+		Commands: []*Command{
+			{
+				Name: "dummy",
+			},
+		},
+	}
+
+	err := app.RunAsSubcommand(newContextFromStringSlice([]string{"", "help"}))
+	if err == nil {
+		t.Fatalf("expected a non-nil error")
+	}
+	if !strings.Contains(err.Error(), "No help topic for 'help'") {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.RunAsSubcommand(newContextFromStringSlice([]string{"", "--help"}))
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestHideHelpCommand_RunAsSubcommand_False(t *testing.T) {
+	app := &App{
+		HideHelpCommand: false,
+		Writer:          ioutil.Discard,
+		Commands: []*Command{
+			{
+				Name: "dummy",
+			},
+		},
+	}
+
+	err := app.RunAsSubcommand(newContextFromStringSlice([]string{"", "help"}))
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.RunAsSubcommand(newContextFromStringSlice([]string{"", "--help"}))
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestHideHelpCommand_WithSubcommands(t *testing.T) {
+	app := &App{
+		Writer: ioutil.Discard,
+		Commands: []*Command{
+			{
+				Name: "dummy",
+				Subcommands: []*Command{
+					{
+						Name: "dummy2",
+					},
+				},
+				HideHelpCommand: true,
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "dummy", "help"})
+	if err == nil {
+		t.Fatalf("expected a non-nil error")
+	}
+	if !strings.Contains(err.Error(), "No help topic for 'help'") {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+
+	err = app.Run([]string{"foo", "dummy", "--help"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}