When no subcommands are registered, omit command help output

For a single root command with a Run method, the help output still
contains 'help [command]' as a subcommand (because Help is always
added). Since the only subcommand would be 'help', the help is better
off omitted.

This change allows a command to be used both as a subcommand
or a root command without having to define a custom help that elides
the help command when no subcommands are added.  Instead, the default
help command is only added when subcommands are present.

cobra_test.go

@@ -136,6 +136,24 @@ func noRRSetupTest(input string) resulter {
 	return fullTester(c, input)
 }
 
+func rootOnlySetupTest(input string) resulter {
+	c := initializeWithRootCmd()
+
+	return simpleTester(c, input)
+}
+
+func simpleTester(c *Command, input string) resulter {
+	buf := new(bytes.Buffer)
+	// Testing flag with invalid input
+	c.SetOutput(buf)
+	c.SetArgs(strings.Split(input, " "))
+
+	err := c.Execute()
+	output := buf.String()
+
+	return resulter{err, output, c}
+}
+
 func fullTester(c *Command, input string) resulter {
 	buf := new(bytes.Buffer)
 	// Testing flag with invalid input
@@ -156,6 +174,12 @@ func checkResultContains(t *testing.T, x resulter, check string) {
 	}
 }
 
+func checkResultOmits(t *testing.T, x resulter, check string) {
+	if strings.Contains(x.Output, check) {
+		t.Errorf("Unexpected response.\nExpecting to omit: \n %q\nGot:\n %q\n", check, x.Output)
+	}
+}
+
 func checkOutputContains(t *testing.T, c *Command, check string) {
 	buf := new(bytes.Buffer)
 	c.SetOutput(buf)
@@ -437,6 +461,7 @@ func TestRootHelp(t *testing.T) {
 	x := fullSetupTest("--help")
 
 	checkResultContains(t, x, "Available Commands:")
+	checkResultContains(t, x, "for more information about that command")
 
 	if strings.Contains(x.Output, "unknown flag: --help") {
 		t.Errorf("--help shouldn't trigger an error, Got: \n %s", x.Output)
@@ -445,6 +470,7 @@ func TestRootHelp(t *testing.T) {
 	x = fullSetupTest("echo --help")
 
 	checkResultContains(t, x, "Available Commands:")
+	checkResultContains(t, x, "for more information about that command")
 
 	if strings.Contains(x.Output, "unknown flag: --help") {
 		t.Errorf("--help shouldn't trigger an error, Got: \n %s", x.Output)
@@ -452,6 +478,26 @@ func TestRootHelp(t *testing.T) {
 
 }
 
+func TestRootNoCommandHelp(t *testing.T) {
+	x := rootOnlySetupTest("--help")
+
+	checkResultOmits(t, x, "Available Commands:")
+	checkResultOmits(t, x, "for more information about that command")
+
+	if strings.Contains(x.Output, "unknown flag: --help") {
+		t.Errorf("--help shouldn't trigger an error, Got: \n %s", x.Output)
+	}
+
+	x = rootOnlySetupTest("echo --help")
+
+	checkResultOmits(t, x, "Available Commands:")
+	checkResultOmits(t, x, "for more information about that command")
+
+	if strings.Contains(x.Output, "unknown flag: --help") {
+		t.Errorf("--help shouldn't trigger an error, Got: \n %s", x.Output)
+	}
+}
+
 func TestFlagsBeforeCommand(t *testing.T) {
 	// short without space
 	x := fullSetupTest("-i10 echo")

command.go

@@ -203,9 +203,9 @@ Available Commands: {{range .Commands}}{{if .Runnable}}
 {{.Flags.FlagUsages}}{{end}}{{if .HasParent}}{{if and (gt .Commands 0) (gt .Parent.Commands 1) }}
 Additional help topics: {{if gt .Commands 0 }}{{range .Commands}}{{if not .Runnable}} {{rpad .CommandPath .CommandPathPadding}} {{.Short}}{{end}}{{end}}{{end}}{{if gt .Parent.Commands 1 }}{{range .Parent.Commands}}{{if .Runnable}}{{if not (eq .Name $cmd.Name) }}{{end}}
   {{rpad .CommandPath .CommandPathPadding}} {{.Short}}{{end}}{{end}}{{end}}{{end}}
-{{end}}
+{{end}}{{ if .HasSubCommands }}
 Use "{{.Root.Name}} help [command]" for more information about that command.
-`
+{{end}}`
 	}
 }
 
@@ -465,6 +465,10 @@ func (c *Command) Execute() (err error) {
 
 func (c *Command) initHelp() {
 	if c.helpCommand == nil {
+		if !c.HasSubCommands() {
+			return
+		}
+
 		c.helpCommand = &Command{
 			Use:   "help [command]",
 			Short: "Help about any command",
@@ -479,6 +483,7 @@ func (c *Command) initHelp() {
 // Used for testing
 func (c *Command) ResetCommands() {
 	c.commands = nil
+	c.helpCommand = nil
 }
 
 func (c *Command) Commands() []*Command {