def test_taking_actions():
"""Does the environment correctly change the state when told to take an action with and without stochasticity?"""
random.seed()
env = Gridworld(4, 4, 0.0)
# Deterministic tests
assert env.next_state(env.initial_state(), Action.up) == env.state_from_grid_position(GridPosition(0, 1))
assert env.next_state(env.initial_state(), Action.down) == env.state_from_grid_position(GridPosition(0, 0))
assert env.next_state(env.initial_state(), Action.left) == env.state_from_grid_position(GridPosition(0, 0))
assert env.next_state(env.initial_state(), Action.right) == env.state_from_grid_position(GridPosition(1, 0))
# Stochastic tests
env.failure_rate = 0.1
assert ratio_test(lambda state: state == env.state_from_grid_position(GridPosition(0, 0)), partial(env.next_state, env.initial_state(), Action.left), 10000) == 1.0
ratio = ratio_test(lambda state: state == env.state_from_grid_position(GridPosition(0, 0)), partial(env.next_state, env.initial_state(), Action.up), 10000)
assert 0.09 < ratio < 0.11
def test_termination():
"""Does the environment terminate in the correct state?"""
env = Gridworld(4, 4, 0)
assert not env.is_terminal(env.state_from_grid_position(GridPosition(0, 0)))
assert env.is_terminal(env.state_from_grid_position(GridPosition(3, 3)))
