summaryrefslogtreecommitdiff
path: root/Lib/test/test_hash.py
blob: e3ab6e4385a9f9d14b7370c6f4654507678aaf3e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
# 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.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:

    # 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,
                                unittest.TestCase):
    repr_ = repr('abc')

    def test_empty_string(self):
        self.assertEqual(hash(""), 0)

class BytesHashRandomizationTests(StringlikeHashRandomizationTests,
                                  unittest.TestCase):
    repr_ = repr(b'abc')

    def test_empty_string(self):
        self.assertEqual(hash(b""), 0)

class MemoryviewHashRandomizationTests(StringlikeHashRandomizationTests,
                                       unittest.TestCase):
    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, 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))


if __name__ == "__main__":
    unittest.main()