1 files changed, 12 insertions, 0 deletions
diff --git a/Lib/test/test_difflib.py b/Lib/test/test_difflib.py
index 5687e32..e33539a 100644
--- a/Lib/test/test_difflib.py
+++ b/Lib/test/test_difflib.py
@@ -1,3 +1,15 @@
 import difflib
 from test import test_support
+import unittest
+
+class TestSFbugs(unittest.TestCase):
+
+    def test_ratio_for_null_seqn(self):
+        # Check clearing of SF bug 763023
+        s = difflib.SequenceMatcher(None, [], [])
+        self.assertEqual(s.ratio(), 1)
+        self.assertEqual(s.quick_ratio(), 1)
+        self.assertEqual(s.real_quick_ratio(), 1)
+
+test_support.run_unittest(TestSFbugs)
 test_support.run_doctest(difflib)