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#
# This file is for everybody to add tests for bugs that aren't
# fixed yet. Please add a test case and appropriate bug description.
#
# When you fix one of the bugs, please move the test to the correct
# test_ module.
#
import unittest
from test import test_support
#
# One test case for outstanding bugs at the moment:
#
class TestDifflibLongestMatch(unittest.TestCase):
# From Patch #1678339:
# The find_longest_match method in the difflib's SequenceMatcher has a bug.
# The bug is in turn caused by a problem with creating a b2j mapping which
# should contain a list of indices for each of the list elements in b.
# However, when the b2j mapping is being created (this is being done in
# __chain_b method in the SequenceMatcher) the mapping becomes broken. The
# cause of this is that for the frequently used elements the list of indices
# is removed and the element is being enlisted in the populardict mapping.
# The test case tries to match two strings like:
# abbbbbb.... and ...bbbbbbc
# The number of b is equal and the find_longest_match should have returned
# the proper amount. However, in case the number of "b"s is large enough, the
# method reports that the length of the longest common substring is 0. It
# simply can't find it.
# A bug was raised some time ago on this matter. It's ID is 1528074.
def test_find_longest_match(self):
import difflib
for i in (190, 200, 210):
text1 = "a" + "b"*i
text2 = "b"*i + "c"
m = difflib.SequenceMatcher(None, text1, text2)
(aptr, bptr, l) = m.find_longest_match(0, len(text1), 0, len(text2))
self.assertEquals(i, l)
self.assertEquals(aptr, 1)
self.assertEquals(bptr, 0)
def test_main():
test_support.run_unittest(TestDifflibLongestMatch)
if __name__ == "__main__":
test_main()
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