ash/test/actions/validation_test.exs

defmodule Ash.Test.Actions.ValidationTest do
  @moduledoc false
  use ExUnit.Case, async: true

  defmodule Profile do
    @moduledoc false
    use Ash.Resource,
      data_layer: Ash.DataLayer.Ets

    ets do
      private? true
    end

    actions do
      read :default
      create :default
      update :default
      destroy :default
    end

    validations do
      validate absent([:bio, :date]), on: :create
      validate present(:bio), on: :update
      validate absent(:date), on: :destroy
    end

    attributes do
      attribute :id, :uuid, primary_key?: true, default: &Ecto.UUID.generate/0
      attribute :bio, :string
      attribute :date, :date
    end
  end

  defmodule Api do
    use Ash.Api

    resources do
      resource Profile
    end
  end

  test "validations run on create" do
    assert_raise(Ash.Error.Invalid, ~r/bio, date: must be absent/, fn ->
      Profile
      |> Ash.Changeset.new(%{bio: "foobar"})
      |> Api.create!()
    end)
  end

  test "validations run on update" do
    assert_raise(Ash.Error.Invalid, ~r/bio: must be present/, fn ->
      Profile
      |> Ash.Changeset.new(%{})
      |> Api.create!()
      |> Ash.Changeset.new(%{})
      |> Api.update!()
    end)
  end

  test "validations run on destroy" do
    assert_raise(Ash.Error.Invalid, ~r/date: must be absent/, fn ->
      Profile
      |> Ash.Changeset.new(%{})
      |> Api.create!()
      |> Ash.Changeset.new(%{bio: "foo", date: Date.utc_today()})
      |> Api.update!()
      |> Api.destroy!()
    end)
  end
end