Demonstrate how to integration test batch callbacks

batch_test_example.ex

def start_supervised_oban!(opts) do
  opts =
    opts
    |> Keyword.put_new(:name, Oban)
    |> Keyword.put_new(:repo, MyApp.Repo)
    |> Keyword.put_new(:poll_interval, :timer.minutes(10))
    |> Keyword.put_new(:shutdown_grace_period, 25)

  pid = start_supervised!({Oban, opts}, id: opts[:name])

  # For Oban < v2.11 you can remove the `{:_, Oban.Peer}` part
  for key <- [{:_, Oban.Peer}, {:_, {:producer, :_}}, {:_, {:plugin, :_}}],
      pid <- Registry.select(Oban.Registry, [{{key, :"$2", :_}, [], [:"$2"]}]) do
    Ecto.Adapters.SQL.Sandbox.allow(MyApp.Repo, self(), pid)
  end

  pid
end

@name MyApp.SomeTest.Oban

@opts [
  name: @name,
  queues: [default: 10]
  plugins: [BatchManager, {Repeater, interval: 25}]
]

test "batch callback args are forwarded to callback jobs" do
  start_supervised_oban!(@opts)

  batch = MyBatch.new_batch([%{ref: 1}, %{ref: 2}])

  Oban.insert_all(@name, batch)

  # verify the batch callback

  stop_supervised(@name)
end