if DB.Model(&user).Association("Languages").Find(&languages); len(languages) != 2 {
		t.Errorf("languages count should be %v, but got %v", 2, len(languages))
	}

	newLang := Language{Code: "omitmany2many", Name: "omitmany2many"}
	if err := DB.Model(&user).Omit("Languages.*").Association("Languages").Replace(&newLang); err == nil {
		t.Errorf("should failed to insert languages due to constraint failed, error: %v", err)
	}
}