Include --help and --version flag in completion

Fixes #1786

The --help, -h, --version and -v flags are normally added when the
`execute()` function is called on a command.  When doing completion
we don't call `execute()` so we need to add these flags explicitly to
the command being completed.

Signed-off-by: Marc Khouzam <marc.khouzam@gmail.com>

completions.go

@@ -274,6 +274,12 @@ func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDi
 	}
 	finalCmd.ctx = c.ctx
 
+	// These flags are normally added when `execute()` is called on `finalCmd`,
+	// however, when doing completion, we don't call `finalCmd.execute()`.
+	// Let's add the --help and --version flag ourselves.
+	finalCmd.InitDefaultHelpFlag()
+	finalCmd.InitDefaultVersionFlag()
+
 	// Check if we are doing flag value completion before parsing the flags.
 	// This is important because if we are completing a flag value, we need to also
 	// remove the flag name argument from the list of finalArgs or else the parsing

completions_test.go

@@ -493,8 +493,9 @@ func TestFlagNameCompletionInGo(t *testing.T) {
 		Run: emptyRun,
 	}
 	childCmd := &Command{
-		Use: "childCmd",
-		Run: emptyRun,
+		Use:     "childCmd",
+		Version: "1.2.3",
+		Run:     emptyRun,
 	}
 	rootCmd.AddCommand(childCmd)
 
@@ -528,6 +529,8 @@ func TestFlagNameCompletionInGo(t *testing.T) {
 	expected = strings.Join([]string{
 		"--first",
 		"-f",
+		"--help",
+		"-h",
 		"--second",
 		"-s",
 		":4",
@@ -561,7 +564,11 @@ func TestFlagNameCompletionInGo(t *testing.T) {
 	expected = strings.Join([]string{
 		"--second",
 		"-s",
+		"--help",
+		"-h",
 		"--subFlag",
+		"--version",
+		"-v",
 		":4",
 		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
 
@@ -576,9 +583,10 @@ func TestFlagNameCompletionInGoWithDesc(t *testing.T) {
 		Run: emptyRun,
 	}
 	childCmd := &Command{
-		Use:   "childCmd",
-		Short: "first command",
-		Run:   emptyRun,
+		Use:     "childCmd",
+		Short:   "first command",
+		Version: "1.2.3",
+		Run:     emptyRun,
 	}
 	rootCmd.AddCommand(childCmd)
 
@@ -612,6 +620,8 @@ func TestFlagNameCompletionInGoWithDesc(t *testing.T) {
 	expected = strings.Join([]string{
 		"--first\tfirst flag",
 		"-f\tfirst flag",
+		"--help\thelp for root",
+		"-h\thelp for root",
 		"--second\tsecond flag",
 		"-s\tsecond flag",
 		":4",
@@ -645,7 +655,11 @@ func TestFlagNameCompletionInGoWithDesc(t *testing.T) {
 	expected = strings.Join([]string{
 		"--second\tsecond flag",
 		"-s\tsecond flag",
+		"--help\thelp for childCmd",
+		"-h\thelp for childCmd",
 		"--subFlag\tsub flag",
+		"--version\tversion for childCmd",
+		"-v\tversion for childCmd",
 		":4",
 		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
 
@@ -688,6 +702,7 @@ func TestFlagNameCompletionRepeat(t *testing.T) {
 	expected := strings.Join([]string{
 		"--array",
 		"--bslice",
+		"--help",
 		"--second",
 		"--slice",
 		":4",
@@ -709,6 +724,7 @@ func TestFlagNameCompletionRepeat(t *testing.T) {
 	expected = strings.Join([]string{
 		"--array",
 		"--bslice",
+		"--help",
 		"--slice",
 		":4",
 		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
@@ -731,6 +747,7 @@ func TestFlagNameCompletionRepeat(t *testing.T) {
 		"--array",
 		"--bslice",
 		"--first",
+		"--help",
 		"--second",
 		"--slice",
 		":4",
@@ -756,6 +773,8 @@ func TestFlagNameCompletionRepeat(t *testing.T) {
 		"-b",
 		"--first",
 		"-f",
+		"--help",
+		"-h",
 		"--second",
 		"-s",
 		"--slice",
@@ -1792,6 +1811,7 @@ func TestFlagCompletionWithNotInterspersedArgs(t *testing.T) {
 
 	expected := strings.Join([]string{
 		"--bool\ttest bool flag",
+		"--help\thelp for child",
 		"--string\ttest string flag",
 		":4",
 		"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n")
@@ -2602,6 +2622,8 @@ func TestCompleteWithDisableFlagParsing(t *testing.T) {
 	expected := strings.Join([]string{
 		"--persistent",
 		"-p",
+		"--help",
+		"-h",
 		"--nonPersistent",
 		"-n",
 		"--flag",
@@ -2624,6 +2646,8 @@ func TestCompleteWithDisableFlagParsing(t *testing.T) {
 	expected = strings.Join([]string{
 		"--persistent",
 		"-p",
+		"--help",
+		"-h",
 		"--nonPersistent",
 		"-n",
 		":4",
@@ -2753,6 +2777,8 @@ func TestCompletionForGroupedFlags(t *testing.T) {
 			expectedOutput: strings.Join([]string{
 				"--ingroup1",
 				"--ingroup2",
+				"--help",
+				"-h",
 				"--ingroup3",
 				"--nogroup",
 				":4",
@@ -2851,6 +2877,8 @@ func TestCompletionForMutuallyExclusiveFlags(t *testing.T) {
 			expectedOutput: strings.Join([]string{
 				"--ingroup1",
 				"--ingroup2",
+				"--help",
+				"-h",
 				"--ingroup3",
 				"--nogroup",
 				":4",
@@ -2861,6 +2889,8 @@ func TestCompletionForMutuallyExclusiveFlags(t *testing.T) {
 			args: []string{"child", "--ingroup1", "8", "-"},
 			expectedOutput: strings.Join([]string{
 				"--ingroup1", // Should be suggested again since it is a slice
+				"--help",
+				"-h",
 				"--nogroup",
 				":4",
 				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
@@ -2869,6 +2899,8 @@ func TestCompletionForMutuallyExclusiveFlags(t *testing.T) {
 			desc: "group ignored if some flags not applicable",
 			args: []string{"--ingroup1", "8", "-"},
 			expectedOutput: strings.Join([]string{
+				"--help",
+				"-h",
 				"--ingroup1",
 				"--ingroup2",
 				":4",