def it_can_change_usage():
lab = Laboratory("apprentice lab")
lab.change_usage("light")
assert lab.usage == "light"
lab.change_usage("heavy")
assert lab.usage == "heavy"
lab.change_usage("typical")
assert lab.usage == "typical"
def it_does_not_accept_atypical_usages():
lab = Laboratory("apprentice lab")
with pytest.raises(ValueError):
lab.change_usage("weird")