async def test_notifier_remove_observer(notifier: Notifier):
def callback1():
...
def callback2():
...
notifier.add_observer('topic', callback1)
notifier.add_observer('topic', callback2)
notifier.remove_observer('topic', callback1)
assert notifier.observers['topic'] == {callback2: True}
async def test_notifier_remove_nonexistent_observer(notifier: Notifier):
# test that `remove_observer` don't crash in case of calling to remove non existed topic/callback
notifier.remove_observer('nonexistent', lambda: None)
assert not notifier.observers['nonexistent']
