def testMutate(self):
random = DummyRandom(randints={(0, 2): [1], # x
(0, 3): [2]}, # y
choiceIndexes=[3])
page = MazePage(size=(3, 4), start=(1, 0), goal=(2, 0))
page.mutate(random)
exits = page[1][2].exits
self.assertEqual(set([(0, -1)]), exits)
