code: def test_step(self):
      board = deepchem.rl.envs.tictactoe.TicTacToeEnvironment()
      X = deepchem.rl.envs.tictactoe.TicTacToeEnvironment.X
      board._state = [np.zeros(shape=(3, 3, 2), dtype=np.float32)]
      board.step(0)
      assert np.all(board.state[0][0][0] == X)
  
file_path: deepchem/deepchem/rl/envs/test_tictactoe.py
imports: from unittest import TestCase
  import numpy
  import deepchem.rl.envs.tictactoe
label_desc: Use image node_id 2 for calling the TestTicTacToeEnvironment obj's underlying member method code with example usage: obj.test_step() without return types