def test_one_string_empty(self):
self.assertEqual(edit_distance("abc", ""), 3)
self.assertEqual(edit_distance("", "abc"), 3)
def test_empty_string(self):
self.assertEqual(edit_distance("", ""), 0)
def test_removal(self):
self.assertEqual(edit_distance("abc", "ac"), 1)
def test_substitution(self):
self.assertEqual(edit_distance("abc", "azc"), 1)
def test_insertion(self):
self.assertEqual(edit_distance("ac", "abc"), 1)