def test_turn_with_invalid_turn_raises_invalid_turn():
heading.turn(None, heading.headings.NORTH)
def test_turn_left():
for left, right in turns:
assert_equals(heading.turn(direction.LEFT, right), left)
def test_turn_with_invalid_heading_raises_invalid_turn():
heading.turn(direction.LEFT, None)
def test_turn_right():
for left, right in turns:
assert_equals(heading.turn(direction.RIGHT, left), right)
