from duck_preview.dispatcher.frame_dispatcher import FrameDispatcher


def test_subscribe_notified():
    dispatcher = FrameDispatcher()
    received = []

    def cb(frame):
        received.append(frame)

    dispatcher.subscribe(cb)
    dispatcher.on_frame("test")

    assert received == ["test"]


def test_unsubscribe_not_notified():
    dispatcher = FrameDispatcher()
    received = []

    def cb(frame):
        received.append(frame)

    dispatcher.subscribe(cb)
    dispatcher.unsubscribe(cb)
    dispatcher.on_frame("test")

    assert received == []


def test_multiple_subscribers():
    dispatcher = FrameDispatcher()
    received_1 = []
    received_2 = []

    def cb1(frame):
        received_1.append(frame)

    def cb2(frame):
        received_2.append(frame)

    dispatcher.subscribe(cb1)
    dispatcher.subscribe(cb2)
    dispatcher.on_frame("test")

    assert received_1 == ["test"]
    assert received_2 == ["test"]