from functools import lru_cache

import pytest


def func(callback):
    return callback()


@pytest.fixture()
def fn(maxsize):
    return lru_cache(maxsize)(func)


@pytest.fixture(params=[1, 2, 5])
def maxsize(request):
    return request.param


class Callback:
    def __init__(self, x):
        self.initial_x = x
        self.x = x

    def __call__(self, *args, **kwargs):
        self.x += 1
        return self.x

    def __hash__(self):
        return hash(self.initial_x)


def test_adding_to_cache_within_maxsize_does_not_overwrite(fn, maxsize):
    c = Callback(0)
    for i in range(maxsize):
        assert fn(c) == 1
    assert fn(c) == 1


def test_adding_to_cache_more_than_maxsize_does_overwrite(fn, maxsize):

    callbacks = [Callback(i) for i in range(maxsize)]

    for i in range(maxsize):
        assert fn(callbacks[i]) == i + 1

    assert fn(Callback(maxsize)) == maxsize + 1
    assert fn(callbacks[0]) == 2