midi_player/test/player_test.exs

defmodule MIDIPlayerTest do
  use ExUnit.Case
  doctest MIDIPlayer

  alias MIDIPlayer, as: Player

  setup do
    {:ok, _pid} = Player.start_link()
    :ok
  end

  setup_all do
    events = Enum.map(1..4, &MIDIPlayer.Event.Note.new(9, 51, &1 * 500, (&1 + 1) * 500, 127))
    duration = 2000
    [events: events, duration: duration]
  end

  test "play", %{events: events, duration: duration} do
    assert :ok = Player.generate_schedule(events, duration)
    assert :ok = Player.play()
    Process.sleep(2500)
  end

  test "pause & resume", %{events: events, duration: duration} do
    Player.generate_schedule(events, duration)
    Player.play()
    Process.sleep(1100)
    assert :ok = Player.pause()
    Process.sleep(500)
    assert :ok = Player.resume()
    Process.sleep(1400)
  end

  test "pause & resume edge cases", %{events: events, duration: duration} do
    Player.generate_schedule(events, duration)
    assert {:error, :not_started} = Player.pause()
    assert {:error, :not_paused} = Player.resume()
    Player.play()
    Player.pause()
    assert {:error, :already_paused} = Player.pause()
  end
end