def test_iterate_until_halt_max(self):
rules = [
Rule("A", 0, 1, True, "B"),
Rule("B", 0, 1, False, "A"),
Rule("C", 0, 1, False, "B"),
Rule("A", 1, 1, False, "C"),
Rule("B", 1, 1, True, "B"),
Rule("C", 1, 1, True, "HALT"),
]
m = Machine(rules)
t = Tape()
s = System(m, t)
with self.assertRaises(DidNotHalt):
s.iterate_until_halt(max_steps=10)
self.assertNotEqual(s.machine.state, "HALT")
def test_iterate_until_halt(self):
rules = [
Rule("A", 0, 1, True, "B"),
Rule("B", 0, 1, False, "A"),
Rule("C", 0, 1, False, "B"),
Rule("A", 1, 1, False, "C"),
Rule("B", 1, 1, True, "B"),
Rule("C", 1, 1, True, "HALT"),
]
m = Machine(rules)
t = Tape()
s = System(m, t)
steps = s.iterate_until_halt()
self.assertEqual(steps, 14)
state, contents, index = s.get_state_tape_contents_and_head_index()
self.assertEqual(state, "HALT")
self.assertEqual(contents, 6 * [1])
self.assertEqual(index, 4)