closes #2130 new command flag ErrorOnUnknownSubcommand

cobra.go

@@ -43,10 +43,11 @@ var initializers []func()
 var finalizers []func()
 
 const (
-	defaultPrefixMatching   = false
-	defaultCommandSorting   = true
-	defaultCaseInsensitive  = false
-	defaultTraverseRunHooks = false
+	defaultPrefixMatching           = false
+	defaultCommandSorting           = true
+	defaultCaseInsensitive          = false
+	defaultTraverseRunHooks         = false
+	defaultErrorOnUnknownSubcommand = false
 )
 
 // EnablePrefixMatching allows setting automatic prefix matching. Automatic prefix matching can be a dangerous thing
@@ -65,6 +66,17 @@ var EnableCaseInsensitive = defaultCaseInsensitive
 // By default this is disabled, which means only the first run hook to be found is executed.
 var EnableTraverseRunHooks = defaultTraverseRunHooks
 
+// EnableErrorOnUnknownSubcommand controls the behavior of subcommand handling.
+// When the flag is set true the behavior of Command.Execute() will change:
+// If a sub-subcommand is not found an error will be returned on calling
+// Command.Exec() instead of the old behavior where a nil error was sent.
+// If the flag is false (default) the old behavior is performed.
+// For this behavior the child subcommand must be nil.
+// Example: in root/service/run - there would be an existing subcommand `run`
+// in root/service/unknown - there would be an unknown subcommand `unknown` therefore returning an error
+// `service` must have a nil Command.Run() function for this.
+var EnableErrorOnUnknownSubcommand = defaultErrorOnUnknownSubcommand
+
 // MousetrapHelpText enables an information splash screen on Windows
 // if the CLI is started from explorer.exe.
 // To disable the mousetrap, just set this variable to blank string ("").

command.go

@@ -923,19 +923,22 @@ func (c *Command) execute(a []string) (err error) {
 		}
 	}
 
-	if !c.Runnable() {
-		return flag.ErrHelp
+	argWoFlags := c.Flags().Args()
+	if c.DisableFlagParsing {
+		argWoFlags = a
 	}
 
+	if !c.Runnable() {
+		if EnableErrorOnUnknownSubcommand && len(argWoFlags) > 0 {
+			return fmt.Errorf("unknown command %q for %q%s", argWoFlags[0], c.CommandPath(), c.findSuggestions(argWoFlags[0]))
+		} else {
+			return flag.ErrHelp
+		}
+	}
 	c.preRun()
 
 	defer c.postRun()
 
-	argWoFlags := c.Flags().Args()
-	if c.DisableFlagParsing {
-		argWoFlags = a
-	}
-
 	if err := c.ValidateArgs(argWoFlags); err != nil {
 		return err
 	}

command_test.go

@@ -174,6 +174,121 @@ func TestSubcommandExecuteC(t *testing.T) {
 	}
 }
 
+func TestSubcommandExecuteMissingSubcommand(t *testing.T) {
+	rootCmd := &Command{Use: "root", Run: emptyRun}
+	const childName = "child"
+	const grandchildName = "grandchild"
+	EnableErrorOnUnknownSubcommand = false
+	defer func() { EnableErrorOnUnknownSubcommand = defaultErrorOnUnknownSubcommand }()
+	childCmd := &Command{Use: childName, Run: nil}
+	child2Cmd := &Command{Use: grandchildName, Run: emptyRun}
+	rootCmd.AddCommand(childCmd)
+	childCmd.AddCommand(child2Cmd)
+
+	// test existing command
+	c, output, err := executeCommandC(rootCmd, childName)
+	if !strings.HasPrefix(output, "Usage:") {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != childName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+
+	// test existing sub command
+	c, output, err = executeCommandC(rootCmd, childName, grandchildName)
+	if output != "" {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != grandchildName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "grandchild"', got: %q`, c.Name())
+	}
+
+	// now test a command which does not exist, we will get no error, just "Usage:" is printed
+	c, output, err = executeCommandC(rootCmd, childName, "unknownChild")
+	if !strings.HasPrefix(output, "Usage:") {
+		t.Errorf("Expected: 'Usage: ...'\nGot:\n %q\n", output)
+	}
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != childName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+}
+
+func TestSubcommandExecuteMissingSubcommandWithErrorOnUnknownSubcommand(t *testing.T) {
+	const rootName = "root"
+	rootCmd := &Command{Use: rootName, Run: emptyRun}
+	const childName = "child"
+	const grandchildName = "grandchild"
+	EnableErrorOnUnknownSubcommand = true
+	defer func() { EnableErrorOnUnknownSubcommand = defaultErrorOnUnknownSubcommand }()
+	childCmd := &Command{Use: childName, Run: nil}
+	child2Cmd := &Command{Use: grandchildName, Run: emptyRun}
+	rootCmd.AddCommand(childCmd)
+	childCmd.AddCommand(child2Cmd)
+
+	// test existing command
+	c, output, err := executeCommandC(rootCmd, childName)
+	if strings.HasPrefix(output, "Error:") {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != childName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+
+	// test existing sub command
+	c, output, err = executeCommandC(rootCmd, childName, grandchildName)
+	if output != "" {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != grandchildName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+
+	// test a child command which does not exist, we expect an error because of the ErrorOnUnknownSubcommand flag
+	c, output, err = executeCommandC(rootCmd, "unknownChild")
+	if !strings.HasPrefix(output, "Error:") {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err == nil {
+		t.Error("Expected error")
+	}
+	if err != nil && !strings.HasPrefix(err.Error(), "unknown command") {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != rootName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+
+	// test a grandchild command which does not exist, we expect an error because of the ErrorOnUnknownSubcommand flag
+	c, output, err = executeCommandC(rootCmd, childName, "unknownGrandChild")
+	if !strings.HasPrefix(output, "Error:") {
+		t.Errorf("Unexpected output: %v", output)
+	}
+	if err == nil {
+		t.Error("Expected error")
+	}
+	if err != nil && !strings.HasPrefix(err.Error(), "unknown command") {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if c.Name() != childName {
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
+	}
+}
+
 func TestExecuteContext(t *testing.T) {
 	ctx := context.TODO()
 

command_win.go

@@ -34,7 +34,7 @@ func preExecHook(c *Command) {
 			time.Sleep(MousetrapDisplayDuration)
 		} else {
 			c.Println("Press return to continue...")
-			fmt.Scanln()
+			_, _ = fmt.Scanln()
 		}
 		os.Exit(1)
 	}