from typing import Iterable

from app.elo import rerank


def test():
    # From https://github.com/sublee/elo/blob/master/elotests.py
    assert _almost_equal(rerank([1200, 800], [1]), [1190.909, 809.091])
    # Couldn't find any test-cases for multiplayer games, so I made this by-hand.
    # The logic I chose for ELO calculation in the face of multiple possible winners has the nice property that a
    # player's outcome score is independent of any other player's outcome - if you win, you get the same ELO score
    # whether "you beat everyone else" or "everybody won". So I could calculate the expected scores by running `rerank`
    # in the single-victory case.
    assert _almost_equal(rerank([1200, 800, 500], [0, 2]), [1203.694, 796.866, 509.438])


def _almost_equal(actual: Iterable, expected: Iterable) -> bool:
    assert len(actual) == len(expected)
    for f, s in zip(actual, expected):
        if (s - f) > (0.00001 * f):
            return False
    else:
        return True