if !compareTags(blog.Tags, []string{"tag1", "tag2", "tag3"}) {
		t.Fatalf("Blog should has three tags after Append")
	}

	if count := DB.Model(&blog).Association("Tags").Count(); count != 3 {
		t.Fatalf("Blog should has 3 tags after Append, got %v", count)
	}

	var tags []Tag
	DB.Model(&blog).Association("Tags").Find(&tags)
	if !compareTags(tags, []string{"tag1", "tag2", "tag3"}) {