defmodule MyApp.Document do
  use Ecto.Schema
  import PolymorphicEmbed

  schema "documents" do
    field :title, :string
    
    # Polymorphic embed field
    polymorphic_embeds_one :content,
      types: [
        text: MyApp.TextContent,
        image: MyApp.ImageContent,
        video: MyApp.VideoContent
      ],
      on_type_not_found: :raise,
      on_replace: :update
  end

  def changeset(document, attrs) do
    document
    |> Ecto.Changeset.cast(attrs, [:title])
    |> cast_polymorphic_embed(:content)  # Required for polymorphic embeds
  end
end

defmodule MyApp.TextContent do
  use Ecto.Schema
  
  embedded_schema do
    field :body, :string
  end
end

defmodule MyApp.Factory do
  use ExMachina.Ecto, repo: MyApp.Repo

  def document_factory do
    %MyApp.Document{
      title: "Test Document",
      content: %MyApp.TextContent{body: "Sample text"}
    }
  end
end

defmodule MyApp.DocumentTest do
  use MyApp.DataCase
  import MyApp.Factory

  test "creates document" do
    # This raises the PolymorphicEmbed error
    document = insert(:document)
    
    assert document.title == "Test Document"
  end
end