Calling unittest.assertDictEqual for medium-size dictionaries takes too long

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
testing-qa

Research direction

Start with the supplied Python reproduction and inspect unittest.assertDictEqual, then read issue #63416 and linked PR gh-126923 for existing context. Done means the medium-size dictionary comparison no longer takes an excessive amount of time, with the behavior checked against the reproduction.

Written by the indexing model from the issue text.

Description

stdlib type-bug

Calling assertDictEqual(d1, d2) / takes forever, even for medium-size dictionaries. To reproduce:

from unittest import TestCase
from random import randint

    def test_assert_dict(self):
        r = 10000000
        num = 10000
        d1 = dict((randint(0, r), randint(0, r)) for _ in range(num))
        d2 = dict((randint(0, r), randint(0, r)) for _ in range(num))
        self.assertDictEqual(d1, d2)

Probably related to issue #63416.

Tested on Python 3.10, Windows 11

Linked PRs
  • gh-126923
Dominant language
Python
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