def test_closure(self):
clos = Closure(6, 16, 2)
self.assertEqual(clos.len(), 6, "incorrect length of closure")
self.assertEqual(clos[0], 6)
self.assertEqual(clos[1], 8)
self.assertEqual(clos[clos.len() - 1], 16)
clos2 = Closure(None, 10, 2)
self.assertEqual(clos2.len(), math.inf,
"incorrect length for unbounded closure")
with self.assertRaises(Exception):
a = clos[8]
with self.assertRaises(Exception):
a = clos2[1]
closWrong = Closure(7, 6, 12)
self.assertEqual(closWrong.len(), 1)
