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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 datetime
import os
import sys
import unittest
from test.support.script_helper import assert_python_ok
from collections.abc import Hashable
IS_64BIT = sys.maxsize > 2**32
def lcg(x, length=16):
"""Linear congruential generator"""
if x == 0:
return bytes(length)
out = bytearray(length)
for i in range(length):
x = (214013 * x + 2531011) & 0x7fffffff
out[i] = (x >> 16) & 0xff
return bytes(out)
def pysiphash(uint64):
"""Convert SipHash24 output to Py_hash_t
"""
assert 0 <= uint64 < (1 << 64)
# simple unsigned to signed int64
if uint64 > (1 << 63) - 1:
int64 = uint64 - (1 << 64)
else:
int64 = uint64
# mangle uint64 to uint32
uint32 = (uint64 ^ uint64 >> 32) & 0xffffffff
# simple unsigned to signed int32
if uint32 > (1 << 31) - 1:
int32 = uint32 - (1 << 32)
else:
int32 = uint32
return int32, int64
def skip_unless_internalhash(test):
"""Skip decorator for tests that depend on SipHash24 or FNV"""
ok = sys.hash_info.algorithm in {"fnv", "siphash24"}
msg = "Requires SipHash24 or FNV"
return test if ok else unittest.skip(msg)(test)
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:
# 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(eval(%a)))' % 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):
repr_ = None
repr_long = None
# 32bit little, 64bit little, 32bit big, 64bit big
known_hashes = {
'djba33x': [ # only used for small strings
# seed 0, 'abc'
[193485960, 193485960, 193485960, 193485960],
# seed 42, 'abc'
[-678966196, 573763426263223372, -820489388, -4282905804826039665],
],
'siphash24': [
# NOTE: PyUCS2 layout depends on endianness
# seed 0, 'abc'
[1198583518, 4596069200710135518, 1198583518, 4596069200710135518],
# seed 42, 'abc'
[273876886, -4501618152524544106, 273876886, -4501618152524544106],
# seed 42, 'abcdefghijk'
[-1745215313, 4436719588892876975, -1745215313, 4436719588892876975],
# seed 0, 'äú∑ℇ'
[493570806, 5749986484189612790, -1006381564, -5915111450199468540],
# seed 42, 'äú∑ℇ'
[-1677110816, -2947981342227738144, -1860207793, -4296699217652516017],
],
'fnv': [
# seed 0, 'abc'
[-1600925533, 1453079729188098211, -1600925533,
1453079729188098211],
# seed 42, 'abc'
[-206076799, -4410911502303878509, -1024014457,
-3570150969479994130],
# seed 42, 'abcdefghijk'
[811136751, -5046230049376118746, -77208053 ,
-4779029615281019666],
# seed 0, 'äú∑ℇ'
[44402817, 8998297579845987431, -1956240331,
-782697888614047887],
# seed 42, 'äú∑ℇ'
[-283066365, -4576729883824601543, -271871407,
-3927695501187247084],
]
}
def get_expected_hash(self, position, length):
if length < sys.hash_info.cutoff:
algorithm = "djba33x"
else:
algorithm = sys.hash_info.algorithm
if sys.byteorder == 'little':
platform = 1 if IS_64BIT else 0
else:
assert(sys.byteorder == 'big')
platform = 3 if IS_64BIT else 2
return self.known_hashes[algorithm][position][platform]
def test_null_hash(self):
# PYTHONHASHSEED=0 disables the randomized hash
known_hash_of_obj = self.get_expected_hash(0, 3)
# 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)
@skip_unless_internalhash
def test_fixed_hash(self):
# test a fixed seed for the randomized hash
# Note that all types share the same values:
h = self.get_expected_hash(1, 3)
self.assertEqual(self.get_hash(self.repr_, seed=42), h)
@skip_unless_internalhash
def test_long_fixed_hash(self):
if self.repr_long is None:
return
h = self.get_expected_hash(2, 11)
self.assertEqual(self.get_hash(self.repr_long, seed=42), h)
class StrHashRandomizationTests(StringlikeHashRandomizationTests,
unittest.TestCase):
repr_ = repr('abc')
repr_long = repr('abcdefghijk')
repr_ucs2 = repr('äú∑ℇ')
@skip_unless_internalhash
def test_empty_string(self):
self.assertEqual(hash(""), 0)
@skip_unless_internalhash
def test_ucs2_string(self):
h = self.get_expected_hash(3, 6)
self.assertEqual(self.get_hash(self.repr_ucs2, seed=0), h)
h = self.get_expected_hash(4, 6)
self.assertEqual(self.get_hash(self.repr_ucs2, seed=42), h)
class BytesHashRandomizationTests(StringlikeHashRandomizationTests,
unittest.TestCase):
repr_ = repr(b'abc')
repr_long = repr(b'abcdefghijk')
@skip_unless_internalhash
def test_empty_string(self):
self.assertEqual(hash(b""), 0)
class MemoryviewHashRandomizationTests(StringlikeHashRandomizationTests,
unittest.TestCase):
repr_ = "memoryview(b'abc')"
repr_long = "memoryview(b'abcdefghijk')"
@skip_unless_internalhash
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, unittest.TestCase):
repr_ = repr(datetime.date(1066, 10, 14))
class DatetimeDatetimeTests(DatetimeTests, unittest.TestCase):
repr_ = repr(datetime.datetime(1, 2, 3, 4, 5, 6, 7))
class DatetimeTimeTests(DatetimeTests, unittest.TestCase):
repr_ = repr(datetime.time(0))
class HashDistributionTestCase(unittest.TestCase):
def test_hash_distribution(self):
# check for hash collision
base = "abcdefghabcdefg"
for i in range(1, len(base)):
prefix = base[:i]
with self.subTest(prefix=prefix):
s15 = set()
s255 = set()
for c in range(256):
h = hash(prefix + chr(c))
s15.add(h & 0xf)
s255.add(h & 0xff)
# SipHash24 distribution depends on key, usually > 60%
self.assertGreater(len(s15), 8, prefix)
self.assertGreater(len(s255), 128, prefix)
if __name__ == "__main__":
unittest.main()
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