From: lighting9999 <lightingcloud999@outlook.com>
Date: Sat, 2 May 2026 12:55:43 +0000 (+0800)
Subject: gh-149221:Fix binomialvariate Function for random module (gh-149222)
X-Git-Tag: v3.15.0b1~121
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4f0cfe53cbb56c32b097f9c38d66444960b5f17f;p=thirdparty%2FPython%2Fcpython.git

gh-149221:Fix binomialvariate Function for random module (gh-149222)
---

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`.