| import difflib | 
 | from test import test_support | 
 | import unittest | 
 | import doctest | 
 |  | 
 | 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) | 
 |  | 
 |     def test_comparing_empty_lists(self): | 
 |         # Check fix for bug #979794 | 
 |         group_gen = difflib.SequenceMatcher(None, [], []).get_grouped_opcodes() | 
 |         self.assertRaises(StopIteration, group_gen.next) | 
 |         diff_gen = difflib.unified_diff([], []) | 
 |         self.assertRaises(StopIteration, diff_gen.next) | 
 |  | 
 | Doctests = doctest.DocTestSuite(difflib) | 
 |  | 
 | test_support.run_unittest(TestSFbugs, Doctests) |