fix createTagItem mutation (#147)

internal/usecase/interactor/tag.go

@@ -70,7 +70,7 @@ func (i *Tag) CreateItem(ctx context.Context, inp interfaces.CreateTagItemParam,
 	}
 
 	if parent != nil {
-		parent.Tags().Add(item.ID())
+		parent.AddTag(item.ID())
 	}
 
 	itemt := tag.Tag(item)

pkg/tag/group.go

@@ -18,3 +18,10 @@ func (g *Group) RemoveTag(ids ...ID) {
 	}
 	g.tags = g.tags.Delete(ids...)
 }
+
+func (g *Group) AddTag(ids ...ID) {
+	if g == nil {
+		return
+	}
+	g.tags = g.tags.Add(ids...)
+}

pkg/tag/group_test.go

@@ -3,6 +3,8 @@ package tag
 import (
 	"testing"
 
+	"github.com/reearth/reearth-backend/pkg/id"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -107,3 +109,54 @@ func TestGroupBuilder_Build(t *testing.T) {
 		})
 	}
 }
+
+func TestGroup_AddTag(t *testing.T) {
+	sid := id.NewSceneID()
+	tid := id.NewTagID()
+	tests := []struct {
+		name     string
+		tag      *Group
+		input    IDList
+		expected IDList
+	}{
+		{
+			name:     "should add a tag",
+			tag:      NewGroup().NewID().Scene(sid).Label("foo").MustBuild(),
+			input:    IDList{tid},
+			expected: IDList{tid},
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(tt *testing.T) {
+			tt.Parallel()
+			tc.tag.AddTag(tc.input...)
+			assert.Equal(tt, tc.tag.tags, tc.expected)
+		})
+	}
+}
+
+func TestGroup_RemoveTag(t *testing.T) {
+	sid := id.NewSceneID()
+	tid := id.NewTagID()
+	tid2 := id.NewTagID()
+	tests := []struct {
+		name     string
+		tag      *Group
+		input    IDList
+		expected IDList
+	}{
+		{
+			name:     "should remove a tag",
+			tag:      NewGroup().NewID().Scene(sid).Label("foo").Tags(IDList{tid, tid2}).MustBuild(),
+			input:    IDList{tid2},
+			expected: IDList{tid},
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(tt *testing.T) {
+			tt.Parallel()
+			tc.tag.RemoveTag(tc.input...)
+			assert.Equal(tt, tc.tag.tags, tc.expected)
+		})
+	}
+}