cpython/Lib/test/test_hash.py

239 lines
7.5 KiB
Python

# test the invariant that
# iff a==b then hash(a)==hash(b)
#
# Also test that hash implementations are inherited as expected
import datetime
import os
import sys
import unittest
from test import support
from test.script_helper import assert_python_ok
from collections import Hashable
IS_64BIT = sys.maxsize > 2**32
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))
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))
def test_unaligned_buffers(self):
# The hash function for bytes-like objects shouldn't have
# alignment-dependent results (example in issue #16427).
b = b"123456789abcdefghijklmnopqrstuvwxyz" * 128
for i in range(16):
for j in range(16):
aligned = b[i:128+j]
unaligned = memoryview(b)[i:128+j]
self.assertEqual(hash(aligned), hash(unaligned))
_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 InheritedHashWithEquality(FixedHash, OnlyEquality): pass
class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
class NoHash(object):
__hash__ = None
class HashInheritanceTestCase(unittest.TestCase):
default_expected = [object(),
DefaultHash(),
OnlyInequality(),
]
fixed_expected = [FixedHash(),
InheritedHashWithEquality(),
InheritedHashWithInequality(),
]
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.assertIsInstance(obj, Hashable)
def test_not_hashable(self):
for obj in self.error_expected:
self.assertNotIsInstance(obj, Hashable)
# Issue #4701: Check that some builtin types are correctly hashable
class DefaultIterSeq(object):
seq = range(10)
def __len__(self):
return len(self.seq)
def __getitem__(self, index):
return self.seq[index]
class HashBuiltinsTestCase(unittest.TestCase):
hashes_to_check = [enumerate(range(10)),
iter(DefaultIterSeq()),
iter(lambda: 0, 0),
]
def test_hashes(self):
_default_hash = object.__hash__
for obj in self.hashes_to_check:
self.assertEqual(hash(obj), _default_hash(obj))
class HashRandomizationTests(unittest.TestCase):
# Each subclass should define a field "repr_", containing the repr() of
# an object to be tested
def get_hash_command(self, repr_):
return 'print(hash(%s))' % repr_
def get_hash(self, repr_, seed=None):
env = os.environ.copy()
env['__cleanenv'] = True # signal to assert_python not to do a copy
# of os.environ on its own
if seed is not None:
env['PYTHONHASHSEED'] = str(seed)
else:
env.pop('PYTHONHASHSEED', None)
out = assert_python_ok(
'-c', self.get_hash_command(repr_),
**env)
stdout = out[1].strip()
return int(stdout)
def test_randomized_hash(self):
# two runs should return different hashes
run1 = self.get_hash(self.repr_, seed='random')
run2 = self.get_hash(self.repr_, seed='random')
self.assertNotEqual(run1, run2)
class StringlikeHashRandomizationTests(HashRandomizationTests):
def test_null_hash(self):
# PYTHONHASHSEED=0 disables the randomized hash
if IS_64BIT:
known_hash_of_obj = 1453079729188098211
else:
known_hash_of_obj = -1600925533
# Randomization is enabled by default:
self.assertNotEqual(self.get_hash(self.repr_), known_hash_of_obj)
# It can also be disabled by setting the seed to 0:
self.assertEqual(self.get_hash(self.repr_, seed=0), known_hash_of_obj)
def test_fixed_hash(self):
# test a fixed seed for the randomized hash
# Note that all types share the same values:
if IS_64BIT:
if sys.byteorder == 'little':
h = -4410911502303878509
else:
h = -3570150969479994130
else:
if sys.byteorder == 'little':
h = -206076799
else:
h = -1024014457
self.assertEqual(self.get_hash(self.repr_, seed=42), h)
class StrHashRandomizationTests(StringlikeHashRandomizationTests):
repr_ = repr('abc')
def test_empty_string(self):
self.assertEqual(hash(""), 0)
class BytesHashRandomizationTests(StringlikeHashRandomizationTests):
repr_ = repr(b'abc')
def test_empty_string(self):
self.assertEqual(hash(b""), 0)
class MemoryviewHashRandomizationTests(StringlikeHashRandomizationTests):
repr_ = "memoryview(b'abc')"
def test_empty_string(self):
self.assertEqual(hash(memoryview(b"")), 0)
class DatetimeTests(HashRandomizationTests):
def get_hash_command(self, repr_):
return 'import datetime; print(hash(%s))' % repr_
class DatetimeDateTests(DatetimeTests):
repr_ = repr(datetime.date(1066, 10, 14))
class DatetimeDatetimeTests(DatetimeTests):
repr_ = repr(datetime.datetime(1, 2, 3, 4, 5, 6, 7))
class DatetimeTimeTests(DatetimeTests):
repr_ = repr(datetime.time(0))
def test_main():
support.run_unittest(HashEqualityTestCase,
HashInheritanceTestCase,
HashBuiltinsTestCase,
StrHashRandomizationTests,
BytesHashRandomizationTests,
MemoryviewHashRandomizationTests,
DatetimeDateTests,
DatetimeDatetimeTests,
DatetimeTimeTests)
if __name__ == "__main__":
test_main()