from collections import OrderedDict
from unittest import main, TestCase

class WorkingSimpleLRUCache(OrderedDict):

    def __init__(self, size):
        super().__init__()
        self.size = size

    def __getitem__(self, item):
        value = super().__getitem__(item)
        del self[item]
        self[item] = value
        return value

    def __setitem__(self, key, value):
        while key not in self and len(self) >= self.size:
            self.popitem(last=False)
        super().__setitem__(key, value)
        self.move_to_end(key)


class FailingSimpleLRUCache(OrderedDict):

    def __init__(self, size):
        super().__init__()
        self.size = size

    def __getitem__(self, item):
        value = super().__getitem__(item)
        self.move_to_end(item)
        return value

    def __setitem__(self, key, value):
        while key not in self and len(self) >= self.size:
            self.popitem(last=False)
        super().__setitem__(key, value)
        self.move_to_end(key)


class BaseTestCase:

    def test_add_after_full(self):
        c = self.cls(2)
        c['t1'] = 1
        c['t2'] = 2
        c['t3'] = 3
        self.assertEqual(list(c), ['t2', 't3'])

    def test_popitem(self):
        c = self.cls(3)
        for i in range(1, 4):
            c[i] = i
        self.assertEqual(c.popitem(last=False), (1, 1))
        self.assertEqual(c.popitem(last=True), (3, 3))

    def test_change_order_on_get(self):
        c = self.cls(3)
        for i in range(1, 4):
            c[i] = i
        self.assertEqual(list(c), list(range(1, 4)))
        self.assertEqual(c[2], 2)
        self.assertEqual(list(c), [1, 3, 2])

class WorkingTestCase(BaseTestCase, TestCase):

    cls = WorkingSimpleLRUCache


class FailingTestCase(BaseTestCase, TestCase):

    cls = FailingSimpleLRUCache

if __name__ == '__main__':
    main()