• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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
6import datetime
7import os
8import sys
9import unittest
10from test.support.script_helper import assert_python_ok
11from collections.abc import Hashable
12
13IS_64BIT = sys.maxsize > 2**32
14
15def lcg(x, length=16):
16    """Linear congruential generator"""
17    if x == 0:
18        return bytes(length)
19    out = bytearray(length)
20    for i in range(length):
21        x = (214013 * x + 2531011) & 0x7fffffff
22        out[i] = (x >> 16) & 0xff
23    return bytes(out)
24
25def pysiphash(uint64):
26    """Convert SipHash24 output to Py_hash_t
27    """
28    assert 0 <= uint64 < (1 << 64)
29    # simple unsigned to signed int64
30    if uint64 > (1 << 63) - 1:
31        int64 = uint64 - (1 << 64)
32    else:
33        int64 = uint64
34    # mangle uint64 to uint32
35    uint32 = (uint64 ^ uint64 >> 32) & 0xffffffff
36    # simple unsigned to signed int32
37    if uint32 > (1 << 31) - 1:
38        int32 = uint32 - (1 << 32)
39    else:
40        int32 = uint32
41    return int32, int64
42
43def skip_unless_internalhash(test):
44    """Skip decorator for tests that depend on SipHash24 or FNV"""
45    ok = sys.hash_info.algorithm in {"fnv", "siphash24"}
46    msg = "Requires SipHash24 or FNV"
47    return test if ok else unittest.skip(msg)(test)
48
49
50class HashEqualityTestCase(unittest.TestCase):
51
52    def same_hash(self, *objlist):
53        # Hash each object given and fail if
54        # the hash values are not all the same.
55        hashed = list(map(hash, objlist))
56        for h in hashed[1:]:
57            if h != hashed[0]:
58                self.fail("hashed values differ: %r" % (objlist,))
59
60    def test_numeric_literals(self):
61        self.same_hash(1, 1, 1.0, 1.0+0.0j)
62        self.same_hash(0, 0.0, 0.0+0.0j)
63        self.same_hash(-1, -1.0, -1.0+0.0j)
64        self.same_hash(-2, -2.0, -2.0+0.0j)
65
66    def test_coerced_integers(self):
67        self.same_hash(int(1), int(1), float(1), complex(1),
68                       int('1'), float('1.0'))
69        self.same_hash(int(-2**31), float(-2**31))
70        self.same_hash(int(1-2**31), float(1-2**31))
71        self.same_hash(int(2**31-1), float(2**31-1))
72        # for 64-bit platforms
73        self.same_hash(int(2**31), float(2**31))
74        self.same_hash(int(-2**63), float(-2**63))
75        self.same_hash(int(2**63), float(2**63))
76
77    def test_coerced_floats(self):
78        self.same_hash(int(1.23e300), float(1.23e300))
79        self.same_hash(float(0.5), complex(0.5, 0.0))
80
81    def test_unaligned_buffers(self):
82        # The hash function for bytes-like objects shouldn't have
83        # alignment-dependent results (example in issue #16427).
84        b = b"123456789abcdefghijklmnopqrstuvwxyz" * 128
85        for i in range(16):
86            for j in range(16):
87                aligned = b[i:128+j]
88                unaligned = memoryview(b)[i:128+j]
89                self.assertEqual(hash(aligned), hash(unaligned))
90
91
92_default_hash = object.__hash__
93class DefaultHash(object): pass
94
95_FIXED_HASH_VALUE = 42
96class FixedHash(object):
97    def __hash__(self):
98        return _FIXED_HASH_VALUE
99
100class OnlyEquality(object):
101    def __eq__(self, other):
102        return self is other
103
104class OnlyInequality(object):
105    def __ne__(self, other):
106        return self is not other
107
108class InheritedHashWithEquality(FixedHash, OnlyEquality): pass
109class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
110
111class NoHash(object):
112    __hash__ = None
113
114class HashInheritanceTestCase(unittest.TestCase):
115    default_expected = [object(),
116                        DefaultHash(),
117                        OnlyInequality(),
118                       ]
119    fixed_expected = [FixedHash(),
120                      InheritedHashWithEquality(),
121                      InheritedHashWithInequality(),
122                      ]
123    error_expected = [NoHash(),
124                      OnlyEquality(),
125                      ]
126
127    def test_default_hash(self):
128        for obj in self.default_expected:
129            self.assertEqual(hash(obj), _default_hash(obj))
130
131    def test_fixed_hash(self):
132        for obj in self.fixed_expected:
133            self.assertEqual(hash(obj), _FIXED_HASH_VALUE)
134
135    def test_error_hash(self):
136        for obj in self.error_expected:
137            self.assertRaises(TypeError, hash, obj)
138
139    def test_hashable(self):
140        objects = (self.default_expected +
141                   self.fixed_expected)
142        for obj in objects:
143            self.assertIsInstance(obj, Hashable)
144
145    def test_not_hashable(self):
146        for obj in self.error_expected:
147            self.assertNotIsInstance(obj, Hashable)
148
149
150# Issue #4701: Check that some builtin types are correctly hashable
151class DefaultIterSeq(object):
152    seq = range(10)
153    def __len__(self):
154        return len(self.seq)
155    def __getitem__(self, index):
156        return self.seq[index]
157
158class HashBuiltinsTestCase(unittest.TestCase):
159    hashes_to_check = [enumerate(range(10)),
160                       iter(DefaultIterSeq()),
161                       iter(lambda: 0, 0),
162                      ]
163
164    def test_hashes(self):
165        _default_hash = object.__hash__
166        for obj in self.hashes_to_check:
167            self.assertEqual(hash(obj), _default_hash(obj))
168
169class HashRandomizationTests:
170
171    # Each subclass should define a field "repr_", containing the repr() of
172    # an object to be tested
173
174    def get_hash_command(self, repr_):
175        return 'print(hash(eval(%a)))' % repr_
176
177    def get_hash(self, repr_, seed=None):
178        env = os.environ.copy()
179        env['__cleanenv'] = True  # signal to assert_python not to do a copy
180                                  # of os.environ on its own
181        if seed is not None:
182            env['PYTHONHASHSEED'] = str(seed)
183        else:
184            env.pop('PYTHONHASHSEED', None)
185        out = assert_python_ok(
186            '-c', self.get_hash_command(repr_),
187            **env)
188        stdout = out[1].strip()
189        return int(stdout)
190
191    def test_randomized_hash(self):
192        # two runs should return different hashes
193        run1 = self.get_hash(self.repr_, seed='random')
194        run2 = self.get_hash(self.repr_, seed='random')
195        self.assertNotEqual(run1, run2)
196
197class StringlikeHashRandomizationTests(HashRandomizationTests):
198    repr_ = None
199    repr_long = None
200
201    # 32bit little, 64bit little, 32bit big, 64bit big
202    known_hashes = {
203        'djba33x': [ # only used for small strings
204            # seed 0, 'abc'
205            [193485960, 193485960,  193485960, 193485960],
206            # seed 42, 'abc'
207            [-678966196, 573763426263223372, -820489388, -4282905804826039665],
208            ],
209        'siphash24': [
210            # NOTE: PyUCS2 layout depends on endianness
211            # seed 0, 'abc'
212            [1198583518, 4596069200710135518, 1198583518, 4596069200710135518],
213            # seed 42, 'abc'
214            [273876886, -4501618152524544106, 273876886, -4501618152524544106],
215            # seed 42, 'abcdefghijk'
216            [-1745215313, 4436719588892876975, -1745215313, 4436719588892876975],
217            # seed 0, 'äú∑ℇ'
218            [493570806, 5749986484189612790, -1006381564, -5915111450199468540],
219            # seed 42, 'äú∑ℇ'
220            [-1677110816, -2947981342227738144, -1860207793, -4296699217652516017],
221        ],
222        'fnv': [
223            # seed 0, 'abc'
224            [-1600925533, 1453079729188098211, -1600925533,
225             1453079729188098211],
226            # seed 42, 'abc'
227            [-206076799, -4410911502303878509, -1024014457,
228             -3570150969479994130],
229            # seed 42, 'abcdefghijk'
230            [811136751, -5046230049376118746, -77208053 ,
231             -4779029615281019666],
232            # seed 0, 'äú∑ℇ'
233            [44402817, 8998297579845987431, -1956240331,
234             -782697888614047887],
235            # seed 42, 'äú∑ℇ'
236            [-283066365, -4576729883824601543, -271871407,
237             -3927695501187247084],
238        ]
239    }
240
241    def get_expected_hash(self, position, length):
242        if length < sys.hash_info.cutoff:
243            algorithm = "djba33x"
244        else:
245            algorithm = sys.hash_info.algorithm
246        if sys.byteorder == 'little':
247            platform = 1 if IS_64BIT else 0
248        else:
249            assert(sys.byteorder == 'big')
250            platform = 3 if IS_64BIT else 2
251        return self.known_hashes[algorithm][position][platform]
252
253    def test_null_hash(self):
254        # PYTHONHASHSEED=0 disables the randomized hash
255        known_hash_of_obj = self.get_expected_hash(0, 3)
256
257        # Randomization is enabled by default:
258        self.assertNotEqual(self.get_hash(self.repr_), known_hash_of_obj)
259
260        # It can also be disabled by setting the seed to 0:
261        self.assertEqual(self.get_hash(self.repr_, seed=0), known_hash_of_obj)
262
263    @skip_unless_internalhash
264    def test_fixed_hash(self):
265        # test a fixed seed for the randomized hash
266        # Note that all types share the same values:
267        h = self.get_expected_hash(1, 3)
268        self.assertEqual(self.get_hash(self.repr_, seed=42), h)
269
270    @skip_unless_internalhash
271    def test_long_fixed_hash(self):
272        if self.repr_long is None:
273            return
274        h = self.get_expected_hash(2, 11)
275        self.assertEqual(self.get_hash(self.repr_long, seed=42), h)
276
277
278class StrHashRandomizationTests(StringlikeHashRandomizationTests,
279                                unittest.TestCase):
280    repr_ = repr('abc')
281    repr_long = repr('abcdefghijk')
282    repr_ucs2 = repr('äú∑ℇ')
283
284    @skip_unless_internalhash
285    def test_empty_string(self):
286        self.assertEqual(hash(""), 0)
287
288    @skip_unless_internalhash
289    def test_ucs2_string(self):
290        h = self.get_expected_hash(3, 6)
291        self.assertEqual(self.get_hash(self.repr_ucs2, seed=0), h)
292        h = self.get_expected_hash(4, 6)
293        self.assertEqual(self.get_hash(self.repr_ucs2, seed=42), h)
294
295class BytesHashRandomizationTests(StringlikeHashRandomizationTests,
296                                  unittest.TestCase):
297    repr_ = repr(b'abc')
298    repr_long = repr(b'abcdefghijk')
299
300    @skip_unless_internalhash
301    def test_empty_string(self):
302        self.assertEqual(hash(b""), 0)
303
304class MemoryviewHashRandomizationTests(StringlikeHashRandomizationTests,
305                                       unittest.TestCase):
306    repr_ = "memoryview(b'abc')"
307    repr_long = "memoryview(b'abcdefghijk')"
308
309    @skip_unless_internalhash
310    def test_empty_string(self):
311        self.assertEqual(hash(memoryview(b"")), 0)
312
313class DatetimeTests(HashRandomizationTests):
314    def get_hash_command(self, repr_):
315        return 'import datetime; print(hash(%s))' % repr_
316
317class DatetimeDateTests(DatetimeTests, unittest.TestCase):
318    repr_ = repr(datetime.date(1066, 10, 14))
319
320class DatetimeDatetimeTests(DatetimeTests, unittest.TestCase):
321    repr_ = repr(datetime.datetime(1, 2, 3, 4, 5, 6, 7))
322
323class DatetimeTimeTests(DatetimeTests, unittest.TestCase):
324    repr_ = repr(datetime.time(0))
325
326
327class HashDistributionTestCase(unittest.TestCase):
328
329    def test_hash_distribution(self):
330        # check for hash collision
331        base = "abcdefghabcdefg"
332        for i in range(1, len(base)):
333            prefix = base[:i]
334            with self.subTest(prefix=prefix):
335                s15 = set()
336                s255 = set()
337                for c in range(256):
338                    h = hash(prefix + chr(c))
339                    s15.add(h & 0xf)
340                    s255.add(h & 0xff)
341                # SipHash24 distribution depends on key, usually > 60%
342                self.assertGreater(len(s15), 8, prefix)
343                self.assertGreater(len(s255), 128, prefix)
344
345if __name__ == "__main__":
346    unittest.main()
347