languages := []Language{
		{Code: "language-many2many-append-1-1", Name: "language-many2many-append-1-1"},
		{Code: "language-many2many-append-2-1", Name: "language-many2many-append-2-1"},
	}
	DB.Create(&languages)

	if err := DB.Model(&user2).Association("Languages").Append(&languages); err != nil {
		t.Fatalf("Error happened when append language, got %v", err)
	}

	user.Languages = append(user.Languages, languages...)