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# test the invariant that
# iff a==b then hash(a)==hash(b)
#
# Also test that hash implementations are inherited as expected
import unittest
from test import support
from collections import Hashable
class HashEqualityTestCase(unittest.TestCase):
def same_hash(self, *objlist):
# Hash each object given and fail if
# the hash values are not all the same.
hashed = list(map(hash, objlist))
for h in hashed[1:]:
if h != hashed[0]:
self.fail("hashed values differ: %r" % (objlist,))
def test_numeric_literals(self):
self.same_hash(1, 1, 1.0, 1.0+0.0j)
self.same_hash(0, 0.0, 0.0+0.0j)
self.same_hash(-1, -1.0, -1.0+0.0j)
self.same_hash(-2, -2.0, -2.0+0.0j)
def test_coerced_integers(self):
self.same_hash(int(1), int(1), float(1), complex(1),
int('1'), float('1.0'))
self.same_hash(int(-2**31), float(-2**31))
self.same_hash(int(1-2**31), float(1-2**31))
self.same_hash(int(2**31-1), float(2**31-1))
# for 64-bit platforms
self.same_hash(int(2**31), float(2**31))
self.same_hash(int(-2**63), float(-2**63))
def test_coerced_floats(self):
self.same_hash(int(1.23e300), float(1.23e300))
self.same_hash(float(0.5), complex(0.5, 0.0))
_default_hash = object.__hash__
class DefaultHash(object): pass
_FIXED_HASH_VALUE = 42
class FixedHash(object):
def __hash__(self):
return _FIXED_HASH_VALUE
class OnlyEquality(object):
def __eq__(self, other):
return self is other
class OnlyInequality(object):
def __ne__(self, other):
return self is not other
class OnlyCmp(object):
def __cmp__(self, other):
return cmp(id(self), id(other))
class InheritedHashWithEquality(FixedHash, OnlyEquality): pass
class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
class InheritedHashWithCmp(FixedHash, OnlyCmp): pass
class NoHash(object):
__hash__ = None
class HashInheritanceTestCase(unittest.TestCase):
default_expected = [object(),
DefaultHash(),
OnlyInequality(),
]
fixed_expected = [FixedHash(),
InheritedHashWithEquality(),
InheritedHashWithInequality(),
InheritedHashWithCmp(),
]
error_expected = [NoHash(),
OnlyEquality(),
]
def test_default_hash(self):
for obj in self.default_expected:
self.assertEqual(hash(obj), _default_hash(obj))
def test_fixed_hash(self):
for obj in self.fixed_expected:
self.assertEqual(hash(obj), _FIXED_HASH_VALUE)
def test_error_hash(self):
for obj in self.error_expected:
self.assertRaises(TypeError, hash, obj)
def test_hashable(self):
objects = (self.default_expected +
self.fixed_expected)
for obj in objects:
self.assert_(isinstance(obj, Hashable), repr(obj))
def test_not_hashable(self):
for obj in self.error_expected:
self.assertFalse(isinstance(obj, Hashable), repr(obj))
def test_main():
support.run_unittest(HashEqualityTestCase,
HashInheritanceTestCase)
if __name__ == "__main__":
test_main()
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