Fix groups not transferring when merging tags (#6127)

* Add test for group when merging tags
* Fix groups not reallocated when merging tags

pkg/sqlite/tag.go

@@ -790,6 +790,7 @@ func (qb *TagStore) Merge(ctx context.Context, source []int, destination int) er
 		imagesTagsTable:      imageIDColumn,
 		"performers_tags":    "performer_id",
 		"studios_tags":       "studio_id",
+		groupsTagsTable:      "group_id",
 	}
 
 	args = append(args, destination)

pkg/sqlite/tag_test.go

@@ -931,6 +931,8 @@ func TestTagMerge(t *testing.T) {
 			tagIdxWithGallery,
 			tagIdx1WithGallery,
 			tagIdx2WithGallery,
+			tagIdx1WithGroup,
+			tagIdx2WithGroup,
 		}
 		var srcIDs []int
 		for _, idx := range srcIdxs {
@@ -1024,6 +1026,18 @@ func TestTagMerge(t *testing.T) {
 
 		assert.Contains(studioTagIDs, destID)
 
+		// ensure group points to new tag
+		group, err := db.Group.Find(ctx, groupIDs[groupIdxWithTwoTags])
+		if err != nil {
+			return err
+		}
+		if err := group.LoadTagIDs(ctx, db.Group); err != nil {
+			return err
+		}
+		groupTagIDs := group.TagIDs.List()
+
+		assert.Contains(groupTagIDs, destID)
+
 		return nil
 	}); err != nil {
 		t.Error(err.Error())