[3.13] gh-149221:Fix binomialvariate Function for random module (#149279)

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: 3 people

Lib/random.py

@@ -828,7 +828,11 @@ def binomialvariate(self, n=1, p=0.5):
             if not c:
                 return x
             while True:
-                y += _floor(_log2(random()) / c) + 1
+                try:
+                    y += _floor(_log2(random()) / c) + 1
+                except ValueError:
+                    # Reject case where random() returned 0.0
+                    continue
                 if y > n:
                     return x
                 x += 1

Lib/test/test_random.py

@@ -1101,6 +1101,13 @@ def test_avg_std(self):
             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_binomialvariate_btrs_random_zero(self):
         for p, expected in ((0.25, 25), (0.75, 75)):
             with self.subTest(p=p):

Misc/NEWS.d/next/Library/2026-05-02-13-54-19.gh-issue-149221.__KOks.rst

@@ -0,0 +1 @@
+Catch rare math domain error for :func:`random.binomialvariate`.