child_3 = Observer()
print("Children Added")
assert(parent.state == "ready")
parent.add_observer(child_1)
parent.add_observer(child_2)
parent.add_observer(child_3)
parent.notify_observers()
assert(parent.state == "ready")
assert(child_1.parent_state == "ready")
assert(child_2.parent_state == "ready")
assert(child_3.parent_state == "ready")
parent.remove_observer(child_2)
#change the state, this should automatically notify observers
parent.set_state("running")
print("Parent State Changed")
assert(parent.state == "running")
assert(child_1.parent_state == "running")
assert(child_2.parent_state == "ready")
assert(child_3.parent_state == "running")
print("Tests Passed")
