unit test

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

cmd/oras/internal/errors/errors.go

@@ -182,16 +182,17 @@ 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.
+// CheckRequiredTogetherFlags checks if any flags required together are all used,
+// returns an error when detecting any flags not used while other flags have been used.
 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 {
+	nUnchangedFlags := len(unchangedFlags)
+	if nUnchangedFlags > 0 && nUnchangedFlags != len(requiredTogetherFlags) {
 		flags := strings.Join(unchangedFlags, ", ")
 		return fmt.Errorf("%s required but not provided", flags)
 	}

cmd/oras/internal/errors/errors_test.go

@@ -0,0 +1,55 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package errors
+
+import (
+	"testing"
+
+	"github.com/spf13/pflag"
+)
+
+func TestCheckRequiredTogetherFlags(t *testing.T) {
+	fs := &pflag.FlagSet{}
+	var foo, bar, hello bool
+	fs.BoolVar(&foo, "foo", false, "foo test")
+	fs.BoolVar(&bar, "bar", false, "bar test")
+	fs.BoolVar(&hello, "hello", false, "hello test")
+	fs.Lookup("foo").Changed = true
+	fs.Lookup("bar").Changed = true
+	tests := []struct {
+		name                  string
+		requiredTogetherFlags []string
+		wantErr               bool
+	}{
+		{
+			"--foo and --bar are both used, no error is returned",
+			[]string{"foo", "bar"},
+			false,
+		},
+		{
+			"--foo and --hello are not both used, an error is returned",
+			[]string{"foo", "hello"},
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := CheckRequiredTogetherFlags(fs, tt.requiredTogetherFlags...); (err != nil) != tt.wantErr {
+				t.Errorf("CheckRequiredTogetherFlags() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}