Complete subcommands when TraverseChildren is true in custom completion

The current custom completion logic does not complete
subcommands when a local flag is set. This is good unless
TraverseChildren is set to true where local flags
can be set on parent commands.

This commit allows subcommands to be completed
if TraverseChildren is set to true on the root cmd.

Closes #1170

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

custom_completions.go

@@ -175,8 +175,16 @@ func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDi
 	toComplete := args[len(args)-1]
 	trimmedArgs := args[:len(args)-1]
 
+	var finalCmd *Command
+	var finalArgs []string
+	var err error
 	// Find the real command for which completion must be performed
-	finalCmd, finalArgs, err := c.Root().Find(trimmedArgs)
+	// check if we need to traverse here to parse local flags on parent commands
+	if c.Root().TraverseChildren {
+		finalCmd, finalArgs, err = c.Root().Traverse(trimmedArgs)
+	} else {
+		finalCmd, finalArgs, err = c.Root().Find(trimmedArgs)
+	}
 	if err != nil {
 		// Unable to find the real command. E.g., <program> someInvalidCmd <TAB>
 		return c, []string{}, ShellCompDirectiveDefault, fmt.Errorf("Unable to find a command for arguments: %v", trimmedArgs)
@@ -271,20 +279,24 @@ func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDi
 	var completions []string
 	directive := ShellCompDirectiveDefault
 	if flag == nil {
-		// Check if there are any local, non-persistent flags on the command-line
 		foundLocalNonPersistentFlag := false
-		localNonPersistentFlags := finalCmd.LocalNonPersistentFlags()
-		finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
-			if localNonPersistentFlags.Lookup(flag.Name) != nil && flag.Changed {
-				foundLocalNonPersistentFlag = true
-			}
-		})
+		// If TraverseChildren is true on the root command we don't check for
+		// local flags because we can use a local flag on a parent command
+		if !finalCmd.Root().TraverseChildren {
+			// Check if there are any local, non-persistent flags on the command-line
+			localNonPersistentFlags := finalCmd.LocalNonPersistentFlags()
+			finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
+				if localNonPersistentFlags.Lookup(flag.Name) != nil && flag.Changed {
+					foundLocalNonPersistentFlag = true
+				}
+			})
+		}
 
 		// Complete subcommand names, including the help command
 		if len(finalArgs) == 0 && !foundLocalNonPersistentFlag {
 			// We only complete sub-commands if:
 			// - there are no arguments on the command-line and
-			// - there are no local, non-peristent flag on the command-line
+			// - there are no local, non-peristent flag on the command-line or TraverseChildren is true
 			for _, subCmd := range finalCmd.Commands() {
 				if subCmd.IsAvailableCommand() || subCmd == finalCmd.helpCommand {
 					if strings.HasPrefix(subCmd.Name(), toComplete) {

custom_completions_test.go

@@ -139,6 +139,8 @@ func TestNoCmdNameCompletionInGo(t *testing.T) {
 		Use: "root",
 		Run: emptyRun,
 	}
+	rootCmd.Flags().String("localroot", "", "local root flag")
+
 	childCmd1 := &Command{
 		Use:   "childCmd1",
 		Short: "First command",
@@ -187,6 +189,64 @@ func TestNoCmdNameCompletionInGo(t *testing.T) {
 		t.Errorf("expected: %q, got: %q", expected, output)
 	}
 
+	// Test that sub-command names are completed if a local non-persistent flag is present and TraverseChildren is set to true
+	// set TraverseChildren to true on the root cmd
+	rootCmd.TraverseChildren = true
+
+	output, err = executeCommand(rootCmd, ShellCompNoDescRequestCmd, "--localroot", "value", "")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	// Reset TraverseChildren for next command
+	rootCmd.TraverseChildren = false
+
+	expected = strings.Join([]string{
+		"childCmd1",
+		"help",
+		":4",
+		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
+
+	if output != expected {
+		t.Errorf("expected: %q, got: %q", expected, output)
+	}
+
+	// Test that sub-command names from a child cmd are completed if a local non-persistent flag is present
+	// and TraverseChildren is set to true on the root cmd
+	rootCmd.TraverseChildren = true
+
+	output, err = executeCommand(rootCmd, ShellCompNoDescRequestCmd, "--localroot", "value", "childCmd1", "--nonPersistent", "value", "")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	// Reset TraverseChildren for next command
+	rootCmd.TraverseChildren = false
+	// Reset the flag for the next command
+	nonPersistentFlag.Changed = false
+
+	expected = strings.Join([]string{
+		"childCmd2",
+		":4",
+		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
+
+	if output != expected {
+		t.Errorf("expected: %q, got: %q", expected, output)
+	}
+
+	// Test that we don't use Traverse when we shouldn't.
+	// This command should not return a completion since the command line is invalid without TraverseChildren.
+	output, err = executeCommand(rootCmd, ShellCompNoDescRequestCmd, "--localroot", "value", "childCmd1", "")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	expected = strings.Join([]string{
+		":0",
+		"Completion ended with directive: ShellCompDirectiveDefault", ""}, "\n")
+
+	if output != expected {
+		t.Errorf("expected: %q, got: %q", expected, output)
+	}
+
 	// Test that sub-command names are not completed if a local non-persistent short flag is present
 	output, err = executeCommand(rootCmd, ShellCompNoDescRequestCmd, "childCmd1", "-n", "value", "")
 	if err != nil {