def test_broken_comparison(self):
class BadClass(object):
def __eq__(self, other):
raise Exception('I have betrayed you!')
def __hash__(self):
return hash((self.__class__, 101))
bad_instance = BadClass()
msg = 'errors should bubble-up for debugging'
with self.assertRaises(Exception, msg=msg):
_require_predicate(bad_instance, 10)
def test_custom_difference(self):
"""When a predicate function returns a difference object,
it should be used in place of an auto-generated one.
"""
pred = lambda x: Invalid('custom')
result = _require_predicate('A', pred, False)
self.assertEqual(result, Invalid('custom'))
def test_eq(self):
"""Should use __eq__() comparison, not __ne__()."""
class EqualsAll(object):
def __init__(_self):
_self.times_checked = 0
def __eq__(_self, other):
_self.times_checked += 1
return True
def __ne__(_self, other):
return NotImplemented
requirement = EqualsAll()
result = _require_predicate('A', requirement)
self.assertEqual(requirement.times_checked, 1)
def test_dict_comparison(self):
result = _require_predicate({'a': 1}, {'a': 2}, True)
self.assertEqual(result, Invalid({'a': 1}, {'a': 2}))
def test_invalid(self):
result = _require_predicate('XX', 10, True)
self.assertEqual(result, Invalid('XX', 10))
def test_deviation(self):
result = _require_predicate(11, 10, True)
self.assertEqual(result, Deviation(+1, 10))
def test_some_invalid(self):
result = _require_predicate('XX', 'A', True)
self.assertEqual(result, Invalid('XX', 'A'))
def test_all_true(self):
result = _require_predicate('A', 'A', True)
self.assertIsNone(result)