如何定义可被ex_machina的params_for识别的工厂？已定义却无法找到

测试代码仅通过use ExMachina.Ecto引入基础功能，但未关联自定义的Booking.Factory模块。ExMachina默认只会在当前测试模块内查找工厂定义，无法识别外部Booking.Factory里的practitioner_factory函数。而IEx中能正常运行，是因为你直接通过Booking.Factory.practitioner_factory!明确指定了工厂所在模块，绕过了这个匹配逻辑。

以下三种方式任选其一即可：

方法1：在测试模块中导入Factory模块 #

添加import Booking.Factory，让测试模块直接调用Factory内的工厂函数：

defmodule Booking.PractitionersTest do
  use ExUnit.Case, async: true
  use Booking.DataCase
  use ExMachina.Ecto
  import Booking.Factory
  alias Ecto.Changeset
  alias Booking.Practitioners.Practitioner

  test "is valid from the factory" do
    new_practitioner = params_for(:practitioner)
    changeset = Practitioner.changeset(Practitioner, new_practitioner)
    assert changeset.valid?
  end
end

方法2：在测试模块中use自定义Factory #

由于Booking.Factory已经集成了ExMachina.Ecto，测试模块可直接use Booking.Factory继承所有工厂功能：

defmodule Booking.PractitionersTest do
  use ExUnit.Case, async: true
  use Booking.DataCase
  use Booking.Factory
  alias Ecto.Changeset
  alias Booking.Practitioners.Practitioner

  test "is valid from the factory" do
    new_practitioner = params_for(:practitioner)
    changeset = Practitioner.changeset(Practitioner, new_practitioner)
    assert changeset.valid?
  end
end

方法3：调用params_for时指定工厂模块 #

如果不想修改测试模块的引入语句，可在调用时明确指定Factory模块：

defmodule Booking.PractitionersTest do
  use ExUnit.Case, async: true
  use Booking.DataCase
  use ExMachina.Ecto
  alias Ecto.Changeset
  alias Booking.Practitioners.Practitioner

  test "is valid from the factory" do
    new_practitioner = Booking.Factory.params_for(:practitioner)
    changeset = Practitioner.changeset(Practitioner, new_practitioner)
    assert changeset.valid?
  end
end

注：测试代码中第24行的Practitioner需要提前通过alias引入，否则会出现模块未定义错误，上述示例已补充该逻辑。

内容的提问来源于stack exchange，提问作者martins