feat: improve error message of when a set of flags is required to use…

… together

Signed-off-by: Xiaoxuan Wang <wangxiaoxuan119@gmail.com>

cmd/oras/internal/errors/errors.go

@@ -181,3 +181,19 @@ func CheckMutuallyExclusiveFlags(fs *pflag.FlagSet, exclusiveFlagSets ...[]strin
 	}
 	return nil
 }
+
+// CheckRequiredTogetherFlags checks if any flags required together are all set,
+// returns an error when detecting any of the required flags not set.
+func CheckRequiredTogetherFlags(fs *pflag.FlagSet, requiredTogetherFlags ...string) error {
+	var unchangedFlags []string
+	for _, flagName := range requiredTogetherFlags {
+		if !fs.Changed(flagName) {
+			unchangedFlags = append(unchangedFlags, fmt.Sprintf("--%s", flagName))
+		}
+	}
+	if len(unchangedFlags) > 0 {
+		flags := strings.Join(unchangedFlags, ", ")
+		return fmt.Errorf("%s required but not provided", flags)
+	}
+	return nil
+}

cmd/oras/internal/option/remote.go

@@ -163,9 +163,9 @@ func (opts *Remote) Parse(cmd *cobra.Command) error {
 	if err := opts.parseCustomHeaders(); err != nil {
 		return err
 	}
-
-	cmd.MarkFlagsRequiredTogether(certFileAndKeyFileFlags...)
-
+	if err := oerrors.CheckRequiredTogetherFlags(cmd.Flags(), certFileAndKeyFileFlags...); err != nil {
+		return err
+	}
 	return opts.readSecret(cmd)
 }