'test levenshtein between two string (in this case, file name)
source :
http://people.cs.pitt.edu/~kirk/cs1501/Pruhs/Fall2006/Assignments/editdistance/Levenshtein%20Distance.htm'

def test_levenshtein(self):

    string1 = 'GUMBO'
    string2 = 'GAMBOL'
    dist = levenshtein_dist(string1, string2)
    dist_swap = levenshtein_dist(string2, string1)
    self.assertEqual(dist, 2, 'Wrong    levenshtein    distance')
    self.assertEqual(dist_swap, 2, 'Wrong    levenshtein    distance')
    string1 = 'ubuntu-15.10-desktop-i386.iso'
    string2 = 'ubuntu-15.10-desktop-amd64.iso'
    dist = levenshtein_dist(string1, string2)
    self.assertEqual(dist, 4, 'Wrong    levenshtein    distance')
    dist = levenshtein_dist(string1, string1)
    self.assertEqual(dist, 0, 'Wrong    levenshtein    distance')
    string2 = 'Learning-Ubuntu-Linux-Server.tgz'
    dist = levenshtein_dist(string1, string2)
    self.assertEqual(dist, 28, 'Wrong    levenshtein    distance')
