Require commands to explicitly state they take arbitrary arguments

The code is riddled with inconsistencies between the root command and
subcommands.  One of those is that the root command cannot take
arbitrary arguments and will complain about invalid subcommands.  But
subcommands will always take arbitrary arguments and will never complain
about invalid sub-sub-commands. I make arbitrary arguments explicitly
listed. You now need to set cmd.TakesArgs = true if you need to be able
to accept arguments tha aren't flags.

This is a pretty major change.

cobra_test.go

@@ -26,6 +26,7 @@ var cmdPrint = &Command{
 	Use:       "print [string to print]",
 	Short:     "Print anything to the screen",
 	Long:      `an absolutely utterly useless command for testing.`,
+	TakesArgs: true,
 	Run: func(cmd *Command, args []string) {
 		tp = args
 	},
@@ -36,6 +37,7 @@ var cmdEcho = &Command{
 	Aliases:   []string{"say"},
 	Short:     "Echo anything to the screen",
 	Long:      `an utterly useless command for testing.`,
+	TakesArgs: true,
 	Run: func(cmd *Command, args []string) {
 		te = args
 	},
@@ -45,11 +47,20 @@ var cmdTimes = &Command{
 	Use:       "times [# times] [string to echo]",
 	Short:     "Echo anything to the screen more times",
 	Long:      `a slightly useless command for testing.`,
+	TakesArgs: true,
 	Run: func(cmd *Command, args []string) {
 		tt = args
 	},
 }
 
+var cmdNoArgs = &Command{
+	Use:   "noargs [because they don't work!!]",
+	Short: "Runnable, but won't take non-flag args",
+	Long:  `something in long form, just because.`,
+	Run: func(cmd *Command, args []string) {
+	},
+}
+
 var cmdRootNoRun = &Command{
 	Use:   "cobra-test",
 	Short: "The root can run it's own function",
@@ -93,6 +104,7 @@ func flagInit() {
 	cmdEcho.ResetFlags()
 	cmdPrint.ResetFlags()
 	cmdTimes.ResetFlags()
+	cmdNoArgs.ResetFlags()
 	cmdRootNoRun.ResetFlags()
 	cmdRootSameName.ResetFlags()
 	cmdRootWithRun.ResetFlags()
@@ -187,7 +199,7 @@ func fullTester(c *Command, input string) resulter {
 	// Testing flag with invalid input
 	c.SetOutput(buf)
 	cmdEcho.AddCommand(cmdTimes)
-	c.AddCommand(cmdPrint, cmdEcho)
+	c.AddCommand(cmdPrint, cmdEcho, cmdNoArgs)
 	c.SetArgs(strings.Split(input, " "))
 
 	err := c.Execute()
@@ -557,6 +569,12 @@ func TestInvalidSubcommandWhenArgsAllowed(t *testing.T) {
 	}
 }
 
+func TestInvalidSubcommandWhenArgsDisallowed(t *testing.T) {
+	x := fullSetupTest("noargs invalid-sub")
+
+	checkResultContains(t, x, "Error: unknown command \"invalid-sub\"\n")
+}
+
 func TestRootFlags(t *testing.T) {
 	fullSetupTest("-i 17 -b")
 

command.go

@@ -42,6 +42,10 @@ type Command struct {
 	Long string
 	// Examples of how to use the command
 	Example string
+	// Accepts arguments that are not defined in flags. This makes subcommand checking and
+	// error reporting less strict as we can cannot tell if `command [arg]` is an incorrect
+	// subcommand or just an argument this command will process.
+	TakesArgs bool
 	// Full set of flags
 	flags *flag.FlagSet
 	// Set of flags childrens of this command will inherit
@@ -377,8 +381,8 @@ func (c *Command) Find(arrs []string) (*Command, []string, error) {
 
 	commandFound, a := innerfind(c, arrs)
 
-	// If we matched on the root, but we asked for a subcommand, return an error
+	// Reject if there are args left and the command doesn't take args
-	if commandFound.Name() == c.Name() && len(stripFlags(arrs, c)) > 0 && commandFound.Name() != arrs[0] {
+	if commandFound.TakesArgs == false && len(stripFlags(a, commandFound)) > 0 {
 		return nil, a, fmt.Errorf("unknown command %q", a[0])
 	}
 
@@ -517,6 +521,7 @@ func (c *Command) initHelp() {
 			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.`,
+			TakesArgs: true,
 			Run:       c.HelpFunc(),
 		}
 	}