From f1caa7513d99fc13ffd67c236248ca0c49f82bb8 Mon Sep 17 00:00:00 2001
From: sivchari <shibuuuu5@gmail.com>
Date: Tue, 29 Apr 2025 14:53:56 +0900
Subject: [PATCH] Add new type to represent validating required flag error

Signed-off-by: sivchari <shibuuuu5@gmail.com>
---
 command.go      | 28 +++++++++++++++++++++++++++-
 command_test.go | 12 ++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/command.go b/command.go
index 4794e5eb..ab46580f 100644
--- a/command.go
+++ b/command.go
@@ -1176,6 +1176,30 @@ func (c *Command) ValidateArgs(args []string) error {
 	return c.Args(c, args)
 }
 
+// RequiredFlagError represents a failure to validate required flags.
+type RequiredFlagError struct {
+	Err error
+}
+
+// Error satisfies the error interface.
+func (r *RequiredFlagError) Error() string {
+	return r.Err.Error()
+}
+
+// Is satisfies the Is error interface.
+func (r *RequiredFlagError) Is(target error) bool {
+	err, ok := target.(*RequiredFlagError)
+	if !ok {
+		return false
+	}
+	return r.Err == err
+}
+
+// Unwrap satisfies Unwrap error interface.
+func (r *RequiredFlagError) Unwrap() error {
+	return r.Err
+}
+
 // ValidateRequiredFlags validates all required flags are present and returns an error otherwise
 func (c *Command) ValidateRequiredFlags() error {
 	if c.DisableFlagParsing {
@@ -1195,7 +1219,9 @@ func (c *Command) ValidateRequiredFlags() error {
 	})
 
 	if len(missingFlagNames) > 0 {
-		return fmt.Errorf(`required flag(s) "%s" not set`, strings.Join(missingFlagNames, `", "`))
+		return &RequiredFlagError{
+			Err: fmt.Errorf(`required flag(s) "%s" not set`, strings.Join(missingFlagNames, `", "`)),
+		}
 	}
 	return nil
 }
diff --git a/command_test.go b/command_test.go
index 156df9eb..97fb6557 100644
--- a/command_test.go
+++ b/command_test.go
@@ -17,6 +17,7 @@ package cobra
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -2952,3 +2953,14 @@ func TestHelpFuncExecuted(t *testing.T) {
 
 	checkStringContains(t, output, helpText)
 }
+
+func TestValidateRequiredFlags(t *testing.T) {
+	c := &Command{Use: "c", Run: emptyRun}
+	c.Flags().BoolP("boola", "a", false, "a boolean flag")
+	c.MarkFlagRequired("boola")
+	if err := c.ValidateRequiredFlags(); !errors.Is(err, &RequiredFlagError{
+		Err: errors.New("required flag(s) \"boola\" not set"),
+	}) {
+		t.Fatalf("Expected error: %v, got: %v", "boola", err)
+	}
+}