from collections import deque import unittest from test.support import NEVER_EQ class base_set: def __init__(self, el): self.el = el class myset(base_set): def __contains__(self, el): return self.el == el class seq(base_set): def __getitem__(self, n): return [self.el][n] class TestContains(unittest.TestCase): def test_common_tests(self): a = base_set(1) b = myset(1) c = seq(1) self.assertIn(1, b) self.assertNotIn(0, b) self.assertIn(1, c) self.assertNotIn(0, c) self.assertRaises(TypeError, lambda: 1 in a) self.assertRaises(TypeError, lambda: 1 not in a) # test char in string self.assertIn('c', 'abc') self.assertNotIn('d', 'abc') self.assertIn('', '') self.assertIn('', 'abc') self.assertRaises(TypeError, lambda: None in 'abc') def test_builtin_sequence_types(self): # a collection of tests on builtin sequence types a = range(10) for i in a: self.assertIn(i, a) self.assertNotIn(16, a) self.assertNotIn(a, a) a = tuple(a) for i in a: self.assertIn(i, a) self.assertNotIn(16, a) self.assertNotIn(a, a) class Deviant1: """Behaves strangely when compared This class is designed to make sure that the contains code works when the list is modified during the check. """ aList = list(range(15)) def __eq__(self, other): if other == 12: self.aList.remove(12) self.aList.remove(13) self.aList.remove(14) return 0 self.assertNotIn(Deviant1(), Deviant1.aList) def test_nonreflexive(self): # containment and equality tests involving elements that are # not necessarily equal to themselves values = float('nan'), 1, None, 'abc', NEVER_EQ constructors = list, tuple, dict.fromkeys, set, frozenset, deque for constructor in constructors: container = constructor(values) for elem in container: self.assertIn(elem, container) self.assertTrue(container == constructor(values)) self.assertTrue(container == container) def test_block_fallback(self): # blocking fallback with __contains__ = None class ByContains(object): def __contains__(self, other): return False c = ByContains() class BlockContains(ByContains): """Is not a container This class is a perfectly good iterable (as tested by list(bc)), as well as inheriting from a perfectly good container, but __contains__ = None prevents the usual fallback to iteration in the container protocol. That is, normally, 0 in bc would fall back to the equivalent of any(x==0 for x in bc), but here it's blocked from doing so. """ def __iter__(self): while False: yield None __contains__ = None bc = BlockContains() self.assertFalse(0 in c) self.assertFalse(0 in list(bc)) self.assertRaises(TypeError, lambda: 0 in bc) if __name__ == '__main__': unittest.main()