wg.Add(1)
		go func(user User, language Language) {
			err := db.Model(&user).Association("Languages").Append(&language)
			AssertEqual(t, err, nil)

			wg.Done()
		}(user, languages[i])
	}
	wg.Wait()

	var find User
	err = db.Preload(clause.Associations).Where("id = ?", user.ID).First(&find).Error
	AssertEqual(t, err, nil)
	AssertAssociationCount(t, find, "Languages", int64(count), "after concurrent append")
}