def test_equal_2(self): self.assertEqual(longest_word('TDWAYZROE'), ['TODAY', 'TOWER', 'TRADE', 'WATER'])
def test_is_none_3(self): self.assertIsNone(longest_word('IIIWUGEZI'))
def test_equal_1(self): self.assertEqual(longest_word('GQEMAUVXY'), ['GAME'])
def test_is_none_1(self): self.assertIsNone(longest_word(''))
def test_is_none_2(self): self.assertIsNone(longest_word('MKMKMKMKM'))
def test_equal_4(self): self.assertEqual(longest_word('AKUIYOOLO'), ['LOOK', 'YOLK'])
def test_equal_5(self): self.assertEqual(longest_word('GVDTCAESU'), ['CAGES', 'CAUSE', 'CAVES', 'DATES', 'GATES', 'GUEST', 'STAGE', 'USAGE'])
def test_equal_3(self): self.assertEqual(longest_word('EAEEAYITB'), ['BEAT', 'BITE', 'BYTE'])
def test_equal_5(self): self.assertEqual(longest_word('GVDTCAESU'), [ 'CAGES', 'CAUSE', 'CAVES', 'DATES', 'GATES', 'GUEST', 'STAGE', 'USAGE' ])