1 files changed, 11 insertions, 0 deletions
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
index 5d12aee169..e2db72330c 100644
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -430,6 +430,17 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase):
             ['0x1.b0580f98a7dbep-1', '0x1.84129978f9c1ap-1',
              '0x1.aeaa51052e978p-2', '0x1.092178fb945a6p-2'])
 
+    def test_bug_31478(self):
+        # There shouldn't be an assertion failure in _random.Random.seed() in
+        # case the argument has a bad __abs__() method.
+        class BadInt(int):
+            def __abs__(self):
+                return None
+        try:
+            self.gen.seed(BadInt())
+        except TypeError:
+            pass
+
     def test_bug_31482(self):
         # Verify that version 1 seeds are unaffected by hash randomization
         # when the seeds are expressed as bytes rather than strings.