bpo-33144: random.Random and subclasses: split _randbelow implementat… · python/cpython@ba3a87a (original) (raw)

`@@ -5,6 +5,7 @@

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`import time

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`import pickle

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`import warnings

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import logging

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`from functools import partial

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`from math import log, exp, pi, fsum, sin, factorial

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`from test import support

`@@ -619,6 +620,16 @@ def test_genrandbits(self):

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`self.assertRaises(ValueError, self.gen.getrandbits, 0)

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`self.assertRaises(ValueError, self.gen.getrandbits, -1)

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def test_randrange_uses_getrandbits(self):

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Verify use of getrandbits by randrange

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Use same seed as in the cross-platform repeatability test

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in test_genrandbits above.

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self.gen.seed(1234567)

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If randrange uses getrandbits, it should pick getrandbits(100)

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when called with a 100-bits stop argument.

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self.assertEqual(self.gen.randrange(2**99),

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97904845777343510404718956115)

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+

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`def test_randbelow_logic(self, _log=log, int=int):

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`# check bitcount transition points: 2i and 2(i+1)-1

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`# show that: k = int(1.001 + _log(n, 2))

`@@ -640,21 +651,22 @@ def test_randbelow_logic(self, _log=log, int=int):

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`self.assertEqual(k, numbits) # note the stronger assertion

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`self.assertTrue(2k > n > 2(k-1)) # note the stronger assertion

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@unittest.mock.patch('random.Random.random')

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def test_randbelow_overridden_random(self, random_mock):

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def test_randbelow_without_getrandbits(self):

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`# Random._randbelow() can only use random() when the built-in one

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`# has been overridden but no new getrandbits() method was supplied.

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random_mock.side_effect = random.SystemRandom().random

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`maxsize = 1<<random.BPF

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`with warnings.catch_warnings():

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`warnings.simplefilter("ignore", UserWarning)

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`# Population range too large (n >= maxsize)

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self.gen._randbelow(maxsize+1, maxsize = maxsize)

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self.gen._randbelow(5640, maxsize = maxsize)

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self.gen._randbelow_without_getrandbits(

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maxsize+1, maxsize=maxsize

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)

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self.gen._randbelow_without_getrandbits(5640, maxsize=maxsize)

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`# issue 33203: test that _randbelow raises ValueError on

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`# n == 0 also in its getrandbits-independent branch.

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`with self.assertRaises(ValueError):

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self.gen._randbelow(0, maxsize=maxsize)

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self.gen._randbelow_without_getrandbits(0, maxsize=maxsize)

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+

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`# This might be going too far to test a single line, but because of our

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`# noble aim of achieving 100% test coverage we need to write a case in

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`# which the following line in Random._randbelow() gets executed:

`@@ -672,8 +684,10 @@ def test_randbelow_overridden_random(self, random_mock):

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`n = 42

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`epsilon = 0.01

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`limit = (maxsize - (maxsize % n)) / maxsize

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random_mock.side_effect = [limit + epsilon, limit - epsilon]

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self.gen._randbelow(n, maxsize = maxsize)

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with unittest.mock.patch.object(random.Random, 'random') as random_mock:

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random_mock.side_effect = [limit + epsilon, limit - epsilon]

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self.gen._randbelow_without_getrandbits(n, maxsize=maxsize)

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self.assertEqual(random_mock.call_count, 2)

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`def test_randrange_bug_1590891(self):

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`start = 1000000000000

`@@ -926,6 +940,49 @@ def test_betavariate_return_zero(self, gammavariate_mock):

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`gammavariate_mock.return_value = 0.0

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`self.assertEqual(0.0, random.betavariate(2.71828, 3.14159))

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class TestRandomSubclassing(unittest.TestCase):

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def test_random_subclass_with_kwargs(self):

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SF bug #1486663 -- this used to erroneously raise a TypeError

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class Subclass(random.Random):

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def init(self, newarg=None):

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random.Random.init(self)

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Subclass(newarg=1)

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+

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def test_subclasses_overriding_methods(self):

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Subclasses with an overridden random, but only the original

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getrandbits method should not rely on getrandbits in for randrange,

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but should use a getrandbits-independent implementation instead.

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+

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subclass providing its own random and getrandbits methods

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like random.SystemRandom does => keep relying on getrandbits for

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randrange

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class SubClass1(random.Random):

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def random(self):

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return super().random()

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+

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def getrandbits(self, n):

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logging.getLogger('getrandbits').info('used getrandbits')

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return super().getrandbits(n)

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with self.assertLogs('getrandbits'):

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SubClass1().randrange(42)

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+

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subclass providing only random => can only use random for randrange

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class SubClass2(random.Random):

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def random(self):

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logging.getLogger('random').info('used random')

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return super().random()

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with self.assertLogs('random'):

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SubClass2().randrange(42)

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+

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subclass defining getrandbits to complement its inherited random

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=> can now rely on getrandbits for randrange again

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class SubClass3(SubClass2):

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def getrandbits(self, n):

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logging.getLogger('getrandbits').info('used getrandbits')

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return super().getrandbits(n)

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with self.assertLogs('getrandbits'):

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SubClass3().randrange(42)

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+

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`class TestModule(unittest.TestCase):

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`def testMagicConstants(self):

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`self.assertAlmostEqual(random.NV_MAGICCONST, 1.71552776992141)

`@@ -937,13 +994,6 @@ def test__all__(self):

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`# tests validity but not completeness of the all list

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`self.assertTrue(set(random.all) <= set(dir(random)))

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