def test_best_guess():
items = {1:'a', 2:'ab', 3:'abc', 4:'abcefg', 5:'abcexyz', 6:'abcxyz', 7:'xyz'}
search = Searchable(items)
search.string = 'abc'
assert(search.best_guess()[0] == 3)
search.string = 'yz'
assert(search.best_guess()[0] == 7)
search.string = 'cex'
assert(search.best_guess()[0] == 5)
items = {1:'twitter', 2:'witter', 3:'twit', 4:'witt', 5:'ftwitter'}
search = Searchable(items)
search.string = 'witte'
assert(search.best_guess()[0] == 2)
