Handy utility function for use in Python tests to wait for a state change triggered by an external or async source

until.py

from time import time, sleep

def wait_until(condition_eval_fn: Callable[[], bool], interval_sec: float, timeout_sec: float):
    start_time = time()

    while not condition_eval_fn() and time() - start_time < timeout_sec:
        sleep(interval_sec)

    if not condition_eval_fn():
        raise TimeoutError("The condition has not been fulfilled within the specified {}s timeout".format(timeout_sec))