For example the following test:

    test "stores the actor that updated the record" do
      actor = generate(user(role: :admin))

      artist = generate(artist(name: "First Name"))
      refute artist.updated_by_id == actor.id

      artist = Music.update_artist!(artist, %{name: "Second Name"}, actor: actor)
      assert artist.updated_by_id == actor.id
    end

Looks very reasonable, but will currently fail with

For safety, we prevent any changes after that point because they will bypass validations or other action logic.. To proceed anyway,
you can use force_change_attribute/3. However, you should prefer a pattern like the below, which makes
any custom changes before calling the action.

  Resource
  |> Ash.Changeset.new()
  |> Ash.Changeset.change_attribute(...)
  |> Ash.Changeset.for_create(...)

Which definitely makes sense – prepare all changes prior creating the change set. But how to tight this up with a generator?