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gh-108963: using random to generate unique string in sys.intern test #109491

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Merged
vstinner merged 6 commits into from
Oct 2, 2023
Merged

gh-108963: using random to generate unique string in sys.intern test #109491

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bdcae08
using random to generate unique string in sys.intern test
aisk Sep 16, 2023
1653d05
remove float in intern test
aisk Sep 19, 2023
a586b39
fix test cases
aisk Sep 19, 2023
4978df9
using random.randrange instead of random.randint and increase range
aisk Sep 19, 2023
785393d
using 9 digits random range in intern test
aisk Sep 21, 2023
14008d9
Merge branch 'main' into fix-gh108963
vstinner Oct 2, 2023
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13 changes: 3 additions & 10 deletions Lib/test/test_sys.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
import locale
import operator
import os
import random
import struct
import subprocess
import sys
Expand All @@ -29,10 +30,6 @@ def requires_subinterpreters(meth):
'subinterpreters required')(meth)


# count the number of test runs, used to create unique
# strings to intern in test_intern()
INTERN_NUMRUNS = 0

DICT_KEY_STRUCT_FORMAT = 'n2BI2n'

class DisplayHookTest(unittest.TestCase):
Expand Down Expand Up @@ -695,10 +692,8 @@ def test_43581(self):
self.assertEqual(sys.__stdout__.encoding, sys.__stderr__.encoding)

def test_intern(self):
global INTERN_NUMRUNS
INTERN_NUMRUNS += 1
self.assertRaises(TypeError, sys.intern)
s = "never interned before" + str(INTERN_NUMRUNS)
s = "never interned before" + str(random.random())
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@vstinner vstinner Sep 18, 2023

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I would prefer using random.randint(), for example 10**9 to have 9 random digits. I prefer to avoid float when possible 😁 Same below.

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@aisk aisk Sep 19, 2023

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Done

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@serhiy-storchaka serhiy-storchaka Sep 19, 2023 •
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But this increases the probability of random failure from 1/253 (about 1/1016) to 1/(9*10**8). If run the test every second, there will be a failure every 30 years in average.

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@aisk aisk Sep 19, 2023 •
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On my machine, the random.random() returns something like 0.35934878814573135, which have 18 digits (with the first zero). So can we just increase the max range to 10 ** 18 to keep the random resolution almost like as the random.random()?

self.assertTrue(sys.intern(s) is s)
s2 = s.swapcase().swapcase()
self.assertTrue(sys.intern(s2) is s)
Expand All @@ -716,9 +711,7 @@ def __hash__(self):

@requires_subinterpreters
def test_subinterp_intern_dynamically_allocated(self):
global INTERN_NUMRUNS
INTERN_NUMRUNS += 1
s = "never interned before" + str(INTERN_NUMRUNS)
s = "never interned before" + str(random.random())
t = sys.intern(s)
self.assertIs(t, s)

Expand Down