Lib/test/test_hash.py

   1 # test the invariant that
   2 #   iff a==b then hash(a)==hash(b)
   3 #
   4 # Also test that hash implementations are inherited as expected
   5
   6 import unittest
   7 from test import test_support
   8 from collections import Hashable
   9
  10
  11 class HashEqualityTestCase(unittest.TestCase):
  12
  13     def same_hash(self, *objlist):
  14         # Hash each object given and fail if
  15         # the hash values are not all the same.
  16         hashed = map(hash, objlist)
  17         for h in hashed[1:]:
  18             if h != hashed[0]:
  19                 self.fail("hashed values differ: %r" % (objlist,))
  20
  21     def test_numeric_literals(self):
  22         self.same_hash(1, 1L, 1.0, 1.0+0.0j)
  23         self.same_hash(0, 0L, 0.0, 0.0+0.0j)
  24         self.same_hash(-1, -1L, -1.0, -1.0+0.0j)
  25         self.same_hash(-2, -2L, -2.0, -2.0+0.0j)
  26
  27     def test_coerced_integers(self):
  28         self.same_hash(int(1), long(1), float(1), complex(1),
  29                        int('1'), float('1.0'))
  30         self.same_hash(int(-2**31), long(-2**31), float(-2**31))
  31         self.same_hash(int(1-2**31), long(1-2**31), float(1-2**31))
  32         self.same_hash(int(2**31-1), long(2**31-1), float(2**31-1))
  33         # for 64-bit platforms
  34         self.same_hash(int(2**31), long(2**31), float(2**31))
  35         self.same_hash(int(-2**63), long(-2**63), float(-2**63))
  36         self.same_hash(int(1-2**63), long(1-2**63))
  37         self.same_hash(int(2**63-1), long(2**63-1))
  38         self.same_hash(long(2**63), float(2**63))
  39
  40     def test_coerced_floats(self):
  41         self.same_hash(long(1.23e300), float(1.23e300))
  42         self.same_hash(float(0.5), complex(0.5, 0.0))
  43
  44
  45 _default_hash = object.__hash__
  46 class DefaultHash(object): pass
  47
  48 _FIXED_HASH_VALUE = 42
  49 class FixedHash(object):
  50     def __hash__(self):
  51         return _FIXED_HASH_VALUE
  52
  53 class OnlyEquality(object):
  54     def __eq__(self, other):
  55         return self is other
  56     # Trick to suppress Py3k warning in 2.x
  57     __hash__ = None
  58 del OnlyEquality.__hash__
  59
  60 class OnlyInequality(object):
  61     def __ne__(self, other):
  62         return self is not other
  63
  64 class OnlyCmp(object):
  65     def __cmp__(self, other):
  66         return cmp(id(self), id(other))
  67     # Trick to suppress Py3k warning in 2.x
  68     __hash__ = None
  69 del OnlyCmp.__hash__
  70
  71 class InheritedHashWithEquality(FixedHash, OnlyEquality): pass
  72 class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
  73 class InheritedHashWithCmp(FixedHash, OnlyCmp): pass
  74
  75 class NoHash(object):
  76     __hash__ = None
  77
  78 class HashInheritanceTestCase(unittest.TestCase):
  79     default_expected = [object(),
  80                         DefaultHash(),
  81                         OnlyEquality(),
  82                         OnlyInequality(),
  83                         OnlyCmp(),
  84                        ]
  85     fixed_expected = [FixedHash(),
  86                       InheritedHashWithEquality(),
  87                       InheritedHashWithInequality(),
  88                       InheritedHashWithCmp(),
  89                       ]
  90     error_expected = [NoHash()]
  91
  92     def test_default_hash(self):
  93         for obj in self.default_expected:
  94             self.assertEqual(hash(obj), _default_hash(obj))
  95
  96     def test_fixed_hash(self):
  97         for obj in self.fixed_expected:
  98             self.assertEqual(hash(obj), _FIXED_HASH_VALUE)
  99
 100     def test_error_hash(self):
 101         for obj in self.error_expected:
 102             self.assertRaises(TypeError, hash, obj)
 103
 104     def test_hashable(self):
 105         objects = (self.default_expected +
 106                    self.fixed_expected)
 107         for obj in objects:
 108             self.assertTrue(isinstance(obj, Hashable), repr(obj))
 109
 110     def test_not_hashable(self):
 111         for obj in self.error_expected:
 112             self.assertFalse(isinstance(obj, Hashable), repr(obj))
 113
 114
 115 # Issue #4701: Check that some builtin types are correctly hashable
 116 #  (This test only used to fail in Python 3.0, but has been included
 117 #   in 2.x along with the lazy call to PyType_Ready in PyObject_Hash)
 118 class DefaultIterSeq(object):
 119     seq = range(10)
 120     def __len__(self):
 121         return len(self.seq)
 122     def __getitem__(self, index):
 123         return self.seq[index]
 124
 125 class HashBuiltinsTestCase(unittest.TestCase):
 126     hashes_to_check = [xrange(10),
 127                        enumerate(xrange(10)),
 128                        iter(DefaultIterSeq()),
 129                        iter(lambda: 0, 0),
 130                       ]
 131
 132     def test_hashes(self):
 133         _default_hash = object.__hash__
 134         for obj in self.hashes_to_check:
 135             self.assertEqual(hash(obj), _default_hash(obj))
 136
 137 def test_main():
 138     test_support.run_unittest(HashEqualityTestCase,
 139                               HashInheritanceTestCase,
 140                               HashBuiltinsTestCase)
 141
 142
 143 if __name__ == "__main__":
 144     test_main()