From 4f0cfe53cbb56c32b097f9c38d66444960b5f17f Mon Sep 17 00:00:00 2001 From: lighting9999 Date: Sat, 2 May 2026 20:55:43 +0800 Subject: [PATCH] gh-149221:Fix binomialvariate Function for random module (gh-149222) --- Lib/random.py | 7 ++++++- Lib/test/test_random.py | 6 ++++++ .../Library/2026-05-02-01-09-29.gh-issue-149221.__KOks.rst | 1 + 3 files changed, 13 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Library/2026-05-02-01-09-29.gh-issue-149221.__KOks.rst diff --git a/Lib/random.py b/Lib/random.py index c89cbb755aba..dc037629bab0 100644 --- a/Lib/random.py +++ b/Lib/random.py @@ -836,7 +836,12 @@ class Random(_random.Random): if not c: return x while True: - y += _floor(_log2(random()) / c) + 1 + try: + y += _floor(_log2(random()) / c) + 1 + # The random() function can return 0.0, which causes log2(0.0) to raise a ValueError. + # See https://github.com/python/cpython/issue/149221 + except ValueError: + continue if y > n: return x x += 1 diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py index 1e57b9244b4f..dbd3b855f536 100644 --- a/Lib/test/test_random.py +++ b/Lib/test/test_random.py @@ -1075,6 +1075,12 @@ class TestDistributions(unittest.TestCase): msg='%s%r' % (variate.__name__, args)) self.assertAlmostEqual(s2/(N-1), sigmasqrd, places=2, msg='%s%r' % (variate.__name__, args)) + def test_binomialvariate_log_zero(self): + # gh-149222: Variety random() return 0.0 no input Error + with unittest.mock.patch.object(random.Random, 'random', side_effect= [0.0] + [0.5] * 20): + result = random.binomialvariate(10, 0.5) + self.assertIsInstance(result, int) + self.assertIn(result, range(11)) def test_constant(self): g = random.Random() diff --git a/Misc/NEWS.d/next/Library/2026-05-02-01-09-29.gh-issue-149221.__KOks.rst b/Misc/NEWS.d/next/Library/2026-05-02-01-09-29.gh-issue-149221.__KOks.rst new file mode 100644 index 000000000000..fab2b0f6a234 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-05-02-01-09-29.gh-issue-149221.__KOks.rst @@ -0,0 +1 @@ +Catch rare math domain error for :func:`random.binomialvariate`. -- 2.47.3