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Python Source  |  2011-02-15  |  3.7 KB  |  121 lines
  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.  
  39.     def test_coerced_floats(self):
  40.         self.same_hash(long(1.23e300), float(1.23e300))
  41.         self.same_hash(float(0.5), complex(0.5, 0.0))
  42.  
  43.  
  44. _default_hash = object.__hash__
  45. class DefaultHash(object): pass
  46.  
  47. _FIXED_HASH_VALUE = 42
  48. class FixedHash(object):
  49.     def __hash__(self):
  50.         return _FIXED_HASH_VALUE
  51.  
  52. class OnlyEquality(object):
  53.     def __eq__(self, other):
  54.         return self is other
  55.     # Trick to suppress Py3k warning in 2.x
  56.     __hash__ = None
  57. del OnlyEquality.__hash__
  58.  
  59. class OnlyInequality(object):
  60.     def __ne__(self, other):
  61.         return self is not other
  62.  
  63. class OnlyCmp(object):
  64.     def __cmp__(self, other):
  65.         return cmp(id(self), id(other))
  66.     # Trick to suppress Py3k warning in 2.x
  67.     __hash__ = None
  68. del OnlyCmp.__hash__
  69.  
  70. class InheritedHashWithEquality(FixedHash, OnlyEquality): pass
  71. class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
  72. class InheritedHashWithCmp(FixedHash, OnlyCmp): pass
  73.  
  74. class NoHash(object):
  75.     __hash__ = None
  76.  
  77. class HashInheritanceTestCase(unittest.TestCase):
  78.     default_expected = [object(),
  79.                         DefaultHash(),
  80.                         OnlyEquality(),
  81.                         OnlyInequality(),
  82.                         OnlyCmp(),
  83.                        ]
  84.     fixed_expected = [FixedHash(),
  85.                       InheritedHashWithEquality(),
  86.                       InheritedHashWithInequality(),
  87.                       InheritedHashWithCmp(),
  88.                       ]
  89.     error_expected = [NoHash()]
  90.  
  91.     def test_default_hash(self):
  92.         for obj in self.default_expected:
  93.             self.assertEqual(hash(obj), _default_hash(obj))
  94.  
  95.     def test_fixed_hash(self):
  96.         for obj in self.fixed_expected:
  97.             self.assertEqual(hash(obj), _FIXED_HASH_VALUE)
  98.  
  99.     def test_error_hash(self):
  100.         for obj in self.error_expected:
  101.             self.assertRaises(TypeError, hash, obj)
  102.  
  103.     def test_hashable(self):
  104.         objects = (self.default_expected +
  105.                    self.fixed_expected)
  106.         for obj in objects:
  107.             self.assert_(isinstance(obj, Hashable), repr(obj))
  108.  
  109.     def test_not_hashable(self):
  110.         for obj in self.error_expected:
  111.             self.assertFalse(isinstance(obj, Hashable), repr(obj))
  112.  
  113.  
  114. def test_main():
  115.     test_support.run_unittest(HashEqualityTestCase,
  116.                               HashInheritanceTestCase)
  117.  
  118.  
  119. if __name__ == "__main__":
  120.     test_main()
  121.