Fix InitDefaultHelpCmd when custom help command is set

command.go

@@ -767,28 +767,28 @@ func (c *Command) InitDefaultHelpFlag() {
 // It is called automatically by executing the c or by calling help and usage.
 // If c already has help command or c has no subcommands, it will do nothing.
 func (c *Command) InitDefaultHelpCmd() {
-	if c.helpCommand != nil || !c.HasSubCommands() {
+	if !c.HasSubCommands() {
 		return
 	}
 
-	c.helpCommand = &Command{
-		Use:   "help [command]",
-		Short: "Help about any command",
-		Long: `Help provides help for any command in the application.
+	if c.helpCommand == nil {
+		c.helpCommand = &Command{
+			Use:   "help [command]",
+			Short: "Help about any command",
+			Long: `Help provides help for any command in the application.
     Simply type ` + c.Name() + ` help [path to command] for full details.`,
-		PersistentPreRun:  func(cmd *Command, args []string) {},
-		PersistentPostRun: func(cmd *Command, args []string) {},
 
-		Run: func(c *Command, args []string) {
-			cmd, _, e := c.Root().Find(args)
-			if cmd == nil || e != nil {
-				c.Printf("Unknown help topic %#q\n", args)
-				c.Root().Usage()
-			} else {
-				cmd.InitDefaultHelpFlag() // make possible 'help' flag to be shown
-				cmd.Help()
-			}
-		},
+			Run: func(c *Command, args []string) {
+				cmd, _, e := c.Root().Find(args)
+				if cmd == nil || e != nil {
+					c.Printf("Unknown help topic %#q\n", args)
+					c.Root().Usage()
+				} else {
+					cmd.InitDefaultHelpFlag() // make possible 'help' flag to be shown
+					cmd.Help()
+				}
+			},
+		}
 	}
 	c.RemoveCommand(c.helpCommand)
 	c.AddCommand(c.helpCommand)

command_test.go

@@ -120,7 +120,6 @@ func TestStripFlags(t *testing.T) {
 }
 
 func TestDisableFlagParsing(t *testing.T) {
-	as := []string{"-v", "-race", "-file", "foo.go"}
 	targs := []string{}
 	cmdPrint := &Command{
 		DisableFlagParsing: true,
@@ -128,14 +127,14 @@ func TestDisableFlagParsing(t *testing.T) {
 			targs = args
 		},
 	}
-	osargs := []string{"cmd"}
-	os.Args = append(osargs, as...)
+	args := []string{"cmd", "-v", "-race", "-file", "foo.go"}
+	cmdPrint.SetArgs(args)
 	err := cmdPrint.Execute()
 	if err != nil {
 		t.Error(err)
 	}
-	if !reflect.DeepEqual(as, targs) {
-		t.Errorf("expected: %v, got: %v", as, targs)
+	if !reflect.DeepEqual(args, targs) {
+		t.Errorf("expected: %v, got: %v", args, targs)
 	}
 }
 
@@ -316,5 +315,35 @@ func TestUseDeprecatedFlags(t *testing.T) {
 	if !strings.Contains(output.String(), "This flag is deprecated") {
 		t.Errorf("Expected to contain deprecated message, but got %q", output.String())
 	}
-
+}
+
+// TestSetHelpCommand checks, if SetHelpCommand works correctly.
+func TestSetHelpCommand(t *testing.T) {
+	c := &Command{Use: "c", Run: func(*Command, []string) {}}
+	output := new(bytes.Buffer)
+	c.SetOutput(output)
+	c.SetArgs([]string{"help"})
+
+	// Help will not be shown, if c has no subcommands.
+	c.AddCommand(&Command{
+		Use: "empty",
+		Run: func(cmd *Command, args []string) {},
+	})
+
+	correctMessage := "WORKS"
+	c.SetHelpCommand(&Command{
+		Use:   "help [command]",
+		Short: "Help about any command",
+		Long: `Help provides help for any command in the application.
+	Simply type ` + c.Name() + ` help [path to command] for full details.`,
+		Run: func(c *Command, args []string) { c.Print(correctMessage) },
+	})
+
+	if err := c.Execute(); err != nil {
+		t.Error("Unexpected error:", err)
+	}
+
+	if output.String() != correctMessage {
+		t.Errorf("Expected to contain %q message, but got %q", correctMessage, output.String())
+	}
 }