def test_standard_ko(self):
# . B . .
# B X B .
# W B W .
# . W . .
gs = GameState(size=9)
gs.do_move((1, 0)) # B
gs.do_move((2, 0)) # W
gs.do_move((2, 1)) # B
gs.do_move((3, 1)) # W
gs.do_move((1, 2)) # B
gs.do_move((2, 2)) # W
gs.do_move((0, 1)) # B
gs.do_move((1, 1)) # W trigger capture and ko
self.assertEqual(gs.num_black_prisoners, 1)
self.assertEqual(gs.num_white_prisoners, 0)
self.assertFalse(gs.is_legal((2, 1)))
gs.do_move((5, 5))
gs.do_move((5, 6))
self.assertTrue(gs.is_legal((2, 1)))
def test_snapback_is_not_ko(self):
gs = GameState(size=5)
# B X W B .
# W W B . .
# . . . . .
# . . . . .
# . . . . .
# imagine black plays at 'X' capturing the white stone at (2, 0).
# White may play again at (2, 0) to capture the black stones
# at (0, 0), (1, 0). this is a 'snapback' not 'ko'
# since it doesn't return the game to a previous position
B = [(0, 0), (2, 1), (3, 0)]
W = [(0, 1), (1, 1), (2, 0)]
for (b, w) in zip(B, W):
gs.do_move(b)
gs.do_move(w)
# do the capture of the single white stone
gs.do_move((1, 0))
# there should be no ko
self.assertIsNone(gs.ko)
self.assertTrue(gs.is_legal((2, 0)))
# now play the snapback
gs.do_move((2, 0))
# check that the numbers worked out
self.assertEqual(gs.num_black_prisoners, 2)
self.assertEqual(gs.num_white_prisoners, 1)